hypothesis about jupiter

Planet Jupiter, explained

From its mysterious core to its stormy surface, there's plenty to learn about the fifth planet from the sun.

The fifth planet from the sun, Jupiter is what watercolor dreams are made of. Vibrant bands of clouds ripple around its thick atmosphere, making up a world so large that more than 1,300 Earths could fit inside. Its Great Red Spot seems to peer out from the swirling vapors like an enormous eye in the face of a striped giant.

Though seemingly serene when viewed from the relative safety of our home world, Jupiter is a chaotic and stormy place . The gas giant planet's spots and swirls come from massive storms that whip up prevailing winds as fast as 335 miles an hour at the equator—faster than any known winds on Earth.

That includes the Great Red Spot, which is a massive hurricane-like storm called an anticyclone. It's far bigger and longer lasting than any tempests that have ever raged across our planet's surface: It rotates in an ever-present oval that's more than the width of the entire Earth, although it has been shrinking for as long as humans have been observing it.

Gas, liquid, or solid?

Jupiter is a massive ball of gas. Its clouds are composed of ammonia and water vapor drifting in an atmosphere of hydrogen and helium. The particular cloud chemistries are likely the magic behind the planet's vibrant colors, but the exact reasons for Jupiter's painted appearance remains unknown.

Below the gassy upper layers, the pressure and temperature increase so much that atoms of hydrogen eventually compress into a liquid. Pressures climb so high that the hydrogen loses its electrons, and the soupy mess can host an electrical charge, just like metal.

The planet's fast spin on its axis means that one Jupiter day lasts less than 10 Earth hours, and it sparks electrical currents that may drive the planet's intense and massive magnetic field, which is 16 to 54 times as powerful as Earth's.

Multitude of moons

Jupiter is the second brightest planet in the night sky, after Venus , which allowed early astronomers to spot and study the massive planet hundreds of years ago. In January 1610, astronomer Galileo Galilei spotted what he thought were four small stars tagging along with Jupiter. These pinpricks of light are actually Jupiter's four largest moons, now known as the Galilean moons: Io, Europa, Ganymede, and Callisto.

Many of these celestial orbs are as remarkable as Jupiter itself. The largest moon in the solar system, Ganymede is also the only moon known to have its own magnetic field. Volcanoes rage on Io's surface, earning it the title of the solar system's most volcanically active body. And scientists believe Europa sports a deep, vast ocean beneath its icy crust , making it a top candidate in the hunt for alien life.

But these are not the planet's only celestial tag-alongs. Jupiter has dozens more—and there may still be more to find. In 2003 alone, astronomers identified 23 new moons. And in June of 2018, researchers discovered 12 more Jovian moons that wander in oddball paths around the giant world.

Missions to Jupiter

Since Galileo first laid telescope-enhanced eyes on Jupiter, scientists have continued to study the curious world from both the ground and the sky. In 1979, NASA's Voyager 1 and 2 spacecraft zipped by the gas giant, taking tens of thousands of pictures as they passed by. Among the surprises from these missions, the data revealed that giant Jupiter sports thin, dusty rings.

And when NASA's Juno spacecraft began orbiting Jupiter in 2016, it quickly started sending back breathtaking images. The stunning pictures revealed that the planet is even more wild than we once thought. Juno returned some of the first detailed looks at the planet's poles , which revealed cyclone swarms gyrating on its surface with roots that likely extend deep below the upper bands of clouds .

Though Jupiter has been so intensely examined, many mysteries remain. One enduring question is what drives Jupiter's Great Red Spot, and what will happen to it in the future. Then there's the question of what actually lies at Jupiter's core. Magnetic field data from the Juno spacecraft suggest that the planet's core is surprisingly large and seems to be made of a partially dissolved solid material. Whatever that is, it's searing hot. Scientists estimate the temperature in this region could be up to 90,032 degrees Fahrenheit —hot enough to melt titanium.

For Hungry Minds

Related topics.

• SOLAR SYSTEM
• SCIENCE AND TECHNOLOGY
• JUNO MISSION

You May Also Like

9 spectacular night sky events to see in 2024

4.5 billion years ago, another planet crashed into Earth. We may have found its leftovers.

Is there a 9th planet out there? We may soon find out.

Planet circling a burned-out star offers a glimpse at the solar system's fate

Planet 9 may be closer and easier to find than thought—if it exists

• Environment
• Perpetual Planet

History & Culture

• History & Culture
• History Magazine
• Gory Details
• Mind, Body, Wonder
• Paid Content
• Terms of Use
• Privacy Policy
• Your US State Privacy Rights
• Children's Online Privacy Policy
• Interest-Based Ads
• About Nielsen Measurement
• Do Not Sell or Share My Personal Information
• Nat Geo Home
• Attend a Live Event
• Book a Trip
• Inspire Your Kids
• Shop Nat Geo
• Visit the D.C. Museum
• Learn About Our Impact
• Support Our Mission
• Advertise With Us
• Customer Service
• Renew Subscription
• Manage Your Subscription
• Work at Nat Geo
• Sign Up for Our Newsletters
• Contribute to Protect the Planet

Copyright © 1996-2015 National Geographic Society Copyright © 2015-2024 National Geographic Partners, LLC. All rights reserved

The Nine Planets

Jupiter Facts

Jupiter is a massive planet, twice the size of all other planets combined and has a centuries-old storm that is bigger than earth..

Jupiter is the fifth planet from the Sun and the largest planet of the Solar System . It is the oldest planet of the Solar System thus it was the first to take shape out of the remains of the solar nebula.

Key Facts & Summary

• Since it is the fourth brightest object in the sky, Jupiter was observed since ancient times and thus no one can be credited for its discovery. However, the first telescopic observations were conducted by Galileo Galilei in 1609 and in 1610 Galileo also discovered the major moons of Jupiter, but of course not the smaller ones.
• Since many cultures observed Jupiter, they all gave it different names but the Roman name remained used in the majority of cultures. Jupiter is named after the principal Roman god, the equivalent of the Greek god Zeus.
• Jupiter is one of the five visible planets (Mercury, Venus, Mars , Saturn), being the fifth most distant from the Sun at an average distance of 5.2 AU, its closest approach is at 4.9 AU and at its farthest 5.4 AU. Its exact position can be checked online since the planet is constantly tracked.
• It is the biggest planet of the Solar System, with a mean radius of 43.440 miles / 69.911 km, a diameter at the equator of about 88.846 mi / 142.984 km, and at the poles, the diameter is only 83.082 mi / 133.708 km.
• Jupiter is also twice as massive as all the other planets combined, having 318 times the mass of Earth.
• The gas giant has a gravity of 24.79 m/s², a little more than twice of Earth. Its powerful gravity has been used to hurl spacecraft into the farthest regions of the solar system.
• Jupiter rotates once every 10 hours – A Jovian day - thus it has the shortest day of all the planets in the solar system.
• A Jovian year is about 12 Earth years, quite long in comparison to its short days.
• Since Jupiter has a small axial tilt of only 3.13 degrees, it has little seasonal variations.

Jupiter does not have a solid surface being comprised mostly out of swirling gases and liquids such as 90% hydrogen, 10% helium – very similar to the sun.

• A very small fraction of the atmosphere is made up of compounds such as ammonia, sulfur, methane, and water vapor. Jupiter’s atmosphere is the largest planetary atmosphere in the solar system . It makes up almost the entire planet.
• It holds a unique place in the history of space exploration since after it was observed through the telescope, some of its moons were also discovered and because of this, their movements were observed thus ending the belief that everything orbited the Earth.
• Though it remains the biggest planet, Jupiter has been dethroned as the moon king by Saturn, which now has 82 moons. Jupiter currently has only 79 known satellites.
• Among these satellites, four of them are quite famous: Io – for its volcanic activity, Ganymede – for its size, being the largest known moon of any planet, Europa – for hosting favorable conditions to find present-day environments suitable for some form of life beyond Earth, and Callisto – that may also host a subsurface ocean. They are known as the Galilean moons.
• Jupiter has 3 ring systems though they are fainter and smaller than Saturn’s. They are mostly made up of dust and small rocky pieces.
• It has a very strong magnetosphere, almost 20 times stronger than Earth’s magnetic field and 20.000 times larger.
• As a result, the aurora of Jupiter is stronger as well. It produces almost a million Megawatts – Earth’s aurora produces about 1.000 Megawatts.
• A distinct feature of Jupiter is its Great Red Spot – a persistent high-pressure region in the atmosphere that produces an anticyclonic storm, the largest in the solar system. It has been observed since 1830, and it is active for hundreds of years. It is also shrinking.
• Jupiter is surrounded by a plasma torus, produced by its strong magnetic field. It is a field of extremely charged particles making it difficult for a spacecraft to approach the planet, yet some zones are a bit safer. The charged particles also come from Io’s volcanic activity.
• The combination of the powerful magnetic field and the charged particles in the plasma torus creates the brightest auroras in the solar system. Sadly, they can only be seen through ultraviolet.
•  It is now known if Jupiter has a core and recent analysis suggests that the atmosphere extends up to 3.000 km / 1.864 mi down, and beneath this is an ocean of metallic hydrogen going all the way down to the center. About 80-90% of its radius is now believed to be a liquid or technically, an electrically conducting plasma, maybe similar to liquid mercury.

Jupiter is the fourth brightest object in the sky, visible to the naked eye. It shines so brightly that even Venus dims in comparison. Because of this, it has been observed since ancient times by many different cultures. The discovery of Jupiter cannot be attributed to someone.

However, Galileo Galilei is the first astronomer to have observed Jupiter through his telescope.  He began extensive observations of the planet in 1609. During this time and until 1610, Galileo discovered the four largest moons that orbit Jupiter: Io, Europa, Ganymede, and Callisto. They are called the Galilean moons in his honor.

He first thought of them as “fixed stars” but over time he witnessed that the objects changed positions, and he even almost correctly deduced their periods. This discovery was revolutionary since, at the time, most of Europe still endorsed the theory that all the planets orbited Earth.

Galileo’s discovery paved the way for the heliocentric model of the solar system, in which the planets orbit the Sun . Jupiter was known to the Babylonians as Marduk, the patron deity of the city of Babylon. The Romans called it “the star of Jupiter” - as they believed it to be sacred to the principal god of Roman mythology, whose name comes from the Proto-Indo-European vocative compound * Dyēu-pəter.

Jupiter is the counterpart to the mythical Greek king of the gods, Zeus, this name is retained even now in the modern Greek language. The ancient Greeks used to call Jupiter, Phaethon, which means “blazing star.” As supreme god of the Roman pantheon, Jupiter was the god of thunder, lightning, and storms, and appropriately called the god of light and sky.

Throughout the universe, there are many planetary systems similar to ours. Most of them contain terrestrial planets like our own and gas giants like Jupiter. However, they also contain super-Earths – planets that are several times more massive than Earth.

This indicates that our own Solar System should also have these types of planets and it is hypothesized that we did have them but they collided with Jupiter in the early formation of the Solar System. This resulted in Jupiter’s migration from the inner solar system to the outer solar system and thus allowed the inner solar planets to form. This theory is called the Grand Tack Hypothesis.

There are theories that hypothesize the fact that Jupiter may have formed before the Sun while others state that Jupiter formed after the sun about 4.5 billion years ago. Gravity pulled swirling gas and dust and resulted in the creation of Jupiter. Sometime around 4 billion years ago Jupiter settled in its current position in the outer solar system.

Distance, Size and Mass

It is the fifth most distant from the Sun with an average distance of about 5.2 AU. The closest approach is at 4.9 AU and at its farthest 5.4 AU. Its exact position can be checked online since the planet is constantly tracked.

It is the biggest planet of the Solar System, with a mean radius of 43.440 miles / 69.911 km. Almost 11 times bigger than Earth. Jupiter's radius is about 1/10 the radius of the Sun, and its mass is 0.001 times the mass of the Sun, so the densities of the two bodies are similar.

The diameter at the equator of about 88.846 mi / 142.984 km, and at the poles, the diameter is only 83.082 mi / 133.708 km. The average density of Jupiter is about 1.326 g/cm 3, much smaller than all the terrestrial planets.

Jupiter is also 2.5 times more massive than all the other planets combined, having 318 times the mass of Earth. It has a volume of about 1,321 Earths.

Orbit and Rotation

Jupiter rotates once every 10 hours – A Jovian day - thus it has the shortest day of all the planets in the solar system. A Jovian year, on the other hand, is about 12 Earth years, quite long in comparison to its short days. The orbital period is about two-fifths that of Saturn . The orbit of Jupiter is elliptical, inclined about 1.31 degrees when compared to Earth .

The eccentricity of the orbit is about 0.048. This results in its distance from the Sun varying from its perihelion to aphelion by about 75 million km / 46 mi. Jupiter’s upper atmosphere undergoes differential rotation since it’s made out of gases.

Since Jupiter has a small axial tilt of only 3.13 degrees, it has little seasonal variations Because of this low tilt the poles constantly receive less solar radiation than at the planet’s equatorial region.

It is now known if Jupiter has a core and recent analysis suggests that the atmosphere extends up to 3.000 km / 1.864 mi down, and beneath this is an ocean of metallic hydrogen going all the way down to the center. About 80-90% of its radius is now believed to be liquid or technically - electrically conducting plasma – it may be similar to liquid mercury. The Juno mission will reveal more about Jupiter’s inner structure and if indeed it has a core.

The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System, spanning over 5.000 km / 3.000 mi in altitude. It is perpetually covered with clouds composed of ammonia crystals and possibly ammonium hydrosulfide.

The clouds are located in the tropopause and are arranged into bands of different latitudes, known as tropical regions sub-divided into lighter-hued zones and darker belts. Because of their interactions, having conflicting circulation patterns, storms and turbulences are created.

Wind speeds of 100 m/s – 360 km/h are common in the zonal jets. The cloud layer is only about 50 km / 31 mi deep, consisting of at least 2 decks of clouds – a thin clearer region and a lower thick one.

The upper atmosphere is calculated to be comprised of about 88-92% hydrogen and 8-12% helium. Since helium atoms have more mass than hydrogen atoms, the composition changes. The atmosphere is thus estimated to be approximately 75% hydrogen and 24% helium with the remaining 1% of the mass consisting of other elements such as methane, water vapor, ammonia, silicon-based compounds, carbon, ethane, oxygen and more.

The outermost layer of the atmosphere contains crystals of frozen ammonia. The interior denser materials by mass are roughly 71% hydrogen, 24% helium and 5% other elements. These atmospheric proportions of hydrogen and helium are close to the theoretical composition of the primordial solar nebula.

Magnetosphere

The magnetic field of Jupiter is fourteen times stronger than that of Earth. It ranges from 4.2 gauss / 0.42 mT at the equator to 10-14 gauss / 1.0 – 1.4 mT at the poles.

This makes Jupiter’s magnetic field the strongest in the Solar System, with the exception of some phenomenon named “sunspots”, that occur on the Sun that are even stronger.

It is believed that the liquid metallic hydrogen present in Jupiter is responsible for this along with the volcanic activity present on Jupiter’s moon Io that emits large amounts of sulfur dioxide forming a gas torus along the moon’s orbit. This gas is ionized in the magnetosphere and through different influences creates a plasma sheet in Jupiter’s equatorial plane. This causes the deformation of the dipole magnetic field into that of a magnetodisk.

As a result, the aurora of Jupiter is stronger as well. It produces almost a million Megawatts – Earth’s aurora, in comparison, produces about 1.000 Megawatts. The combination of the powerful magnetic field and the charged particles from Io in the plasma torus creates the brightest auroras in the solar system. Sadly, most of them can only be seen through ultraviolet.

Because Jupiter is surrounded by this plasma torus, produced by its strong magnetic field, it makes it very difficult for a spacecraft to approach the planet, yet some zones are not so dangerous but the radiation is still present.

Data suggests that the temperature on Jupiter varies from -145 degrees Celsius / -234 degrees Fahrenheit in the clouds too much higher temperatures near the planet’s center. Some estimates concluded that it would get even hotter than the surface of the Sun.

One of the key features of Jupiter is its Great Red Spot. A storm that’s existed since 1831, and possibly since 1665. This oval-shaped object is greater in size than Earth and rotates counterclockwise within a period of six days. Its maximum altitude is about 8 km / 5 mi above the surrounding cloud tops. Since its discovery, it has decreased in size and recent observations state that it decreases in length by about 930 km / 580 mi per year. Storms are common on Jupiter, some are small and last hours while others are huge and last for centuries. Wind speeds of 100 m/s – 360 km/h are common on certain parts of the planet.

Jupiter was the king of the moons since recently, having a total of 79 known satellites. Recently, Saturn dethroned Jupiter having a total of 82 known satellites. These rankings can change as observations continue.

Out of the 79 satellites, 63 are less than 10 km / 6.2 mi in diameter, and have only been observed since 1975. The Galilean moons, Io, Europa, Ganymede, and Callisto are large enough to be seen from Earth with binoculars. They are among the largest satellites discovered in the Solar System with Ganymede being the largest out of all the satellites in our solar system.

Jupiter has both regular moons and irregular moons with further sub-divisions.

Regular moons

The regular moons of Jupiter consists of the Galilean moons and an inner group of 4 small moons with diameters less than 200 km / 124 mi, and orbits with radii less than 200.000 km / 124.274 mi. They all have orbital inclinations of less than half a degree. The Galilean moons orbit between 400.000 and 2.000.000 km – 248.548 mi and 1.242.742 mi. These moons are believed to have been formed together with Jupiter since they have nearly circular orbits near the plane of Jupiter’s equator.

Despite being the largest known satellite in the solar system, it lacks a substantial atmosphere.  It is the 9 th largest object in the solar system with a diameter of 5.268 km / 3.273 mi and is 8% larger than the planet Mercury, although only 45% as massive.

It was named after the mythological cupbearer of the Greek gods, who was kidnapped by Zeus for this purpose. It is the only moon known to have a magnetic field and though it posseses a metallic core, it has the lowest moment of inertia factor of any solid body in the Solar System.

Outward from Jupiter, it is the seventh satellite completing an orbit around Jupiter in about 7 Earth days. It is in a 1:2:4 orbital resonance with the moons Europa and Io. It is comprised mostly of equal amounts of silicate rock and water ice, having an iron-rich, liquid core, and an internal ocean that may contain more water than all of Earth’s oceans combined.

A third of its surface is covered by dark regions covered in impact craters and a light region, crosscut by extensive grooves and ridges possibly due to tectonic activity due to tidal heating. It has a thin atmosphere comprised of oxygen, ozone and other elements. There is some speculation on the potential habitability of Ganymede's ocean.

The innermost and third-largest of the four Galilean moons of Jupiter, Io is the fourth-largest moon the solar system with the highest density and the least amount of water molecules of any known astronomical object in the Solar System.

Named after the mythological character Io, a priestess of Hera who became one of Zeus’ lovers, Io is the most geological active object in the Solar system having over 400 active volcanoes.

This extreme geological activity is due to tidal heating caused from friction generated within Io’s interior as it is pulled between Jupiter and the other Galilean moons.

It takes Io 1.77 Earth-days to orbit Jupiter. It is tidally locked to Jupiter, showing only one side to its parent planet, and has a mean radius of 1.131 miles / 1.821 km, slightly larger than Earth’s moon.

Many of Io’s volcanoes produce plumes of 500 km / 300 mi above the surface. More than 100 mountains are uplifted by extensive compression at the base of Io’s silicate crust. Some of these peaks are taller than Mount Everest, the highest point on Earth’s surface.

Io is composed primarily of silicate rock that surrounds a molten iron core. The plains of Io are coated with sulfur and sulfur-dioxide frost. The materials produced by Io’s volcanism make up its thin atmosphere, and result in the large plasma torus around Jupiter.

Europa is the smallest of the four Galilean moons and the sixth largest of all the moons in the Solar System. It was named after the Phoenician mother of King Minos of Crete and lover of Zeus.

It is slightly smaller than Earth’s moon having a diameter of 3.100 km / 1.900 mi. It is primarily made of silicate rock and has a water-ice crust, and a probably iron-nickel core.

Its atmosphere is thin, composed primarily of oxygen. The surface is very smooth. In fact it is the smoothest of any known solid object in the Solar System. The apparent youth of the smoothness of the surface led to the hypothesis that a water ocean exists beneath it, which could conceivably harbor extraterrestrial life.

Currently, Europa probably has the highest of either having or developing life, and thus it is one of the most closely studied objects in the solar system.

Callisto is the second-largest moon of Jupiter and the third-largest moon in the Solar System after Ganymede and Saturn’s moon Titan. It has a diameter of about 4.821 km / 2.995 mi, having about 99% the diameter of the planet Mercury but only a third of its mass.

Named after a nymph of Greek mythology, also another one of Zeus’s lovers, Callisto is the farthest Galilean moon orbiting Saturn at a distance of 1.8 million km. It is not in a orbital resonance like the other three Galilean moons and thus it is not appreciably tidally heated like the others. It is tidally locked with Jupiter and it is less affected by Jupiter’s magnetosphere than the other inner satellites because of its remote orbit.

It is composed primarily out of equal amounts of rock and ices, with a density of about 1.83 g/cm 3 , the lowest of Jupiter’s satellites. Investigations by the Galileo spacecraft suggest that Callisto has a silicate core and possibly a subsurface ocean of liquid water at depths of 100 km.

Interestingly, the surface of Callisto is the oldest and most heavily cratered in the Solar System. It has an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen.

The presence of an ocean within Callisto opens the possibility that it could harbor life but conditions are thought to be less favorable than on Europa. Regardless, it is considered the most suitable planet for a human base for future exploration of the Jovian system due to low radiation levels.

Irregular Moons

The irregular moons are small and have elliptical and inclined orbits. They are thought to be captured asteroids or fragments of captured asteroids. Their exact number is unknown but they are further divided into sub-divisions – groups, in which they share similar orbital elements and thus may have a common origin.

There are 4 groups:

• The Himalia group – a clustered group of moons with orbits around 11 million to 12 million km / 6 to 7 million mi from Jupiter.
• The Ananke group – a group with a retrograde orbit with rather indistinct borders, averaging from 21 million km / 13 million mi from Jupiter with an average inclination of 149 degrees.
• The Carme group – they are a group with a fairly distinct retrograde orbit that averages from 23 million km / 14 million mi from Jupiter with an average inclination of 165 degrees.
• The Pasiphae group – a very dispersed and only vaguely distinct retrograde group that covers all the outermost moons.
• There are three irregular moons that stand out from these groups:
• Themisto – it orbits halfway between the Galilean moons and the Himalia group.
• Carpo – it is at the inner edge of the Ananke group and orbits Jupiter in prograde direction.
• Valetudo – this moon has a prograde orbit but overlaps the retrograde groups and may result in future collisions with those groups.

Planetary Rings

Jupiter has a faint planetary ring system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring.

They appear to be made out of dust rather than ice as with Saturn’s rings. It is believed that the main ring is made of material ejected from the satellites Adrastea and Metis.

In a similar manor, the moons Thebe and Amalthea probably produce the two distinct components of the dusty gossamer ring.

Life Habitability

Since it doesn’t have a true surface but rather swirling fluids it is not conducive to life as we know it. Ganymede, Callisto, and Europa on the other hand, have higher chances of sustaining life.

Future plans for Jupiter

Juno is a spacecraft that was launched in 2011 and even now it is still analyzing Jupiter and sending data. Future missions are already set in motion for Ganymede, Europa, Callisto and Io. They are set to be launched on 2020 and 2026. The high probability of life, the powerful volcanic activity and the overall missing details of Jupiter are strong factors in driving these missions.

Did you know?

• When Jupiter was formed it had twice its current diameter.
• Jupiter shrinks 2 cm every year because it radiates too much heath.
• Jupiter is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center. It is the only planet whose barycenter with the Sun lies outside the volume of the Sun.
• If Jupiter would be 75 times more massive, it would probably become a star.
• If a person who weighs 100 pounds on Earth would somehow stand on the surface of Jupiter, that person would weigh about 240 pounds due to Jupiter’s gravitational force.
• Although Simon Marius, a German astronomer, is not credited with the sole discovery of the Galilean satellites, his names for the moons were adopted.
• Jupiter experiences almost 200 times more asteroid and comet impacts than Earth
• Jupiter has been called the Solar System's vacuum cleaner, because of its immense gravity well. It receives the most frequent comet impacts of the Solar System's planets.
• It was thought that the planet served to partially shield the inner system from cometary bombardment. However, recent computer simulations suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward roughly as often as it accretes or ejects them. This topic remains controversial.
• Jupiter may have been responsible for the Late Heavy Bombardment of the inner Solar System's history.

Image source:

• https://upload.wikimedia.org/wikipedia/commons/5/50/Jupiter%2C_image_taken_by_NASA%27s_Hubble_Space_Telescope%2C_June_2019_-_Edited.jpg
• https://upload.wikimedia.org/wikipedia/commons/c/cb/Jupiter-bonatti.png
• https://upload.wikimedia.org/wikipedia/commons/0/02/SolarSystem_OrdersOfMagnitude_Sun-Jupiter-Earth-Moon.jpg
• https://www.inverse.com/article/56489-jupiter-at-opposition-2019
• https://upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Jupiter_diagram.svg/800px-Jupiter_diagram.svg.png
• https://upload.wikimedia.org/wikipedia/commons/8/84/PIA21973-AboveTheCloudsOfJupiter-JunoSpacecraft-20171216.jpg
• https://upload.wikimedia.org/wikipedia/commons/0/04/Hubble_Captures_Vivid_Auroras_in_Jupiter%27s_Atmosphere.jpg
• https://upload.wikimedia.org/wikipedia/commons/3/30/NASA14135-Jupiter-GreatRedSpot-Shrinks-20140515.jpg
• https://upload.wikimedia.org/wikipedia/commons/f/f2/Ganymede_g1_true-edit1.jpg
• https://upload.wikimedia.org/wikipedia/commons/7/7b/Io_highest_resolution_true_color.jpg
• https://upload.wikimedia.org/wikipedia/commons/e/e4/Europa-moon-with-margins.jpg
• https://upload.wikimedia.org/wikipedia/commons/e/e9/Callisto.jpg
• https://upload.wikimedia.org/wikipedia/commons/2/29/PIA01627_Ringe.jpg

Jupiter is the fifth planet from our Sun and is, by far, the largest planet in the solar system – more than twice as massive as all the other planets combined. Jupiter's stripes and swirls are actually cold, windy clouds of ammonia and water, floating in an atmosphere of hydrogen and helium. Jupiter’s iconic Great Red Spot is a giant storm bigger than Earth that has raged for hundreds of years.

Jupiter is surrounded by dozens of moons. Jupiter also has several rings, but unlike the famous rings of Saturn, Jupiter’s rings are very faint and made of dust, not ice.

Jupiter, being the biggest planet, gets its name from the king of the ancient Roman gods.

Potential for Life

Jupiter’s environment is probably not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.

While planet Jupiter is an unlikely place for living things to take hold, the same is not true of some of its many moons. Europa is one of the likeliest places to find life elsewhere in our solar system. There is evidence of a vast ocean just beneath its icy crust, where life could possibly be supported.

Size and Distance

With a radius of 43,440.7 miles (69,911 kilometers), Jupiter is 11 times wider than Earth. If Earth were the size of a nickel, Jupiter would be about as big as a basketball.

From an average distance of 484 million miles (778 million kilometers), Jupiter is 5.2 astronomical units away from the Sun. One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth. From this distance, it takes Sunlight 43 minutes to travel from the Sun to Jupiter.

Orbit and Rotation

Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the Sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days).

Its equator is tilted with respect to its orbital path around the Sun by just 3 degrees. This means Jupiter spins nearly upright and does not have seasons as extreme as other planets do.

With four large moons and many smaller moons, Jupiter forms a kind of miniature solar system. Jupiter has 80 moons. Fifty-seven moons have been given official names by the International Astronomical Union (IAU). Another 23 moons are awaiting names.

Jupiter's four largest moons – Io, Europa, Ganymede, and Callisto – were first observed by the astronomer Galileo Galilei in 1610 using an early version of the telescope. These four moons are known today as the Galilean satellites, and they're some of the most fascinating destinations in our solar system. Io is the most volcanically active body in the solar system. Ganymede is the largest moon in the solar system (even bigger than the planet Mercury). Callisto’s very few small craters indicate a small degree of current surface activity. A liquid-water ocean with the ingredients for life may lie beneath the frozen crust of Europa, making it a tempting place to explore.

› More on Jupiter's Moons

Discovered in 1979 by NASA's Voyager 1 spacecraft, Jupiter's rings were a surprise, as they are composed of small, dark particles and are difficult to see except when backlit by the Sun. Data from the Galileo spacecraft indicate that Jupiter's ring system may be formed by dust kicked up as interplanetary meteoroids smash into the giant planet's small innermost moons.

Jupiter took shape when the rest of the solar system formed about 4.5 billion years ago when gravity pulled swirling gas and dust in to become this gas giant. Jupiter took most of the mass left over after the formation of the Sun, ending up with more than twice the combined material of the other bodies in the solar system. In fact, Jupiter has the same ingredients as a star, but it did not grow massive enough to ignite.

About 4 billion years ago, Jupiter settled into its current position in the outer solar system, where it is the fifth planet from the Sun.

The composition of Jupiter is similar to that of the Sun – mostly hydrogen and helium. Deep in the atmosphere, pressure and temperature increase, compressing the hydrogen gas into a liquid. This gives Jupiter the largest ocean in the solar system – an ocean made of hydrogen instead of water. Scientists think that, at depths perhaps halfway to the planet's center, the pressure becomes so great that electrons are squeezed off the hydrogen atoms, making the liquid electrically conducting like metal. Jupiter's fast rotation is thought to drive electrical currents in this region, generating the planet's powerful magnetic field. It is still unclear if deeper down, Jupiter has a central core of solid material or if it may be a thick, super-hot and dense soup. It could be up to 90,032 degrees Fahrenheit (50,000 degrees Celsius) down there, made mostly of iron and silicate minerals (similar to quartz).

As a gas giant, Jupiter doesn’t have a true surface. The planet is mostly swirling gases and liquids. While a spacecraft would have nowhere to land on Jupiter, it wouldn’t be able to fly through unscathed either. The extreme pressures and temperatures deep inside the planet crush, melt, and vaporize spacecraft trying to fly into the planet.

Jupiter's appearance is a tapestry of colorful cloud bands and spots. The gas planet likely has three distinct cloud layers in its "skies" that, taken together, span about 44 miles (71 kilometers). The top cloud is probably made of ammonia ice, while the middle layer is likely made of ammonium hydrosulfide crystals. The innermost layer may be made of water ice and vapor.

The vivid colors you see in thick bands across Jupiter may be plumes of sulfur and phosphorus-containing gases rising from the planet's warmer interior. Jupiter's fast rotation – spinning once every 10 hours – creates strong jet streams, separating its clouds into dark belts and bright zones across long stretches.

With no solid surface to slow them down, Jupiter's spots can persist for many years. Stormy Jupiter is swept by over a dozen prevailing winds, some reaching up to 335 miles per hour (539 kilometers per hour) at the equator. The Great Red Spot, a swirling oval of clouds twice as wide as Earth, has been observed on the giant planet for more than 300 years. More recently, three smaller ovals merged to form the Little Red Spot, about half the size of its larger cousin.

Findings from NASA’s Juno probe released in October 2021 provide a fuller picture of what’s going on below those clouds. Data from Juno shows that Jupiter’s cyclones are warmer on top, with lower atmospheric densities, while they are colder at the bottom, with higher densities. Anticyclones, which rotate in the opposite direction, are colder at the top but warmer at the bottom.

The findings also indicate these storms are far taller than expected, with some extending 60 miles (100 kilometers) below the cloud tops and others, including the Great Red Spot, extending over 200 miles (350 kilometers). This surprising discovery demonstrates that the vortices cover regions beyond those where water condenses and clouds form, below the depth where sunlight warms the atmosphere.

The height and size of the Great Red Spot mean the concentration of atmospheric mass within the storm potentially could be detectable by instruments studying Jupiter’s gravity field. Two close Juno flybys over Jupiter’s most famous spot provided the opportunity to search for the storm’s gravity signature and complement the other results on its depth.

With their gravity data, the Juno team was able to constrain the extent of the Great Red Spot to a depth of about 300 miles (500 kilometers) below the cloud tops.

Belts and Zones In addition to cyclones and anticyclones, Jupiter is known for its distinctive belts and zones – white and reddish bands of clouds that wrap around the planet. Strong east-west winds moving in opposite directions separate the bands. Juno previously discovered that these winds, or jet streams, reach depths of about 2,000 miles (roughly 3,200 kilometers). Researchers are still trying to solve the mystery of how the jet streams form. Data collected by Juno during multiple passes reveal one possible clue: that the atmosphere’s ammonia gas travels up and down in remarkable alignment with the observed jet streams.

Juno’s data also shows that the belts and zones undergo a transition around 40 miles (65 kilometers) beneath Jupiter’s water clouds. At shallow depths, Jupiter’s belts are brighter in microwave light than the neighboring zones. But at deeper levels, below the water clouds, the opposite is true – which reveals a similarity to our oceans.

Polar Cyclones Juno previously discovered polygonal arrangements of giant cyclonic storms at both of Jupiter’s poles – eight arranged in an octagonal pattern in the north and five arranged in a pentagonal pattern in the south. Over time, mission scientists determined these atmospheric phenomena are extremely resilient, remaining in the same location.

Juno data also indicates that, like hurricanes on Earth, these cyclones want to move poleward, but cyclones located at the center of each pole push them back. This balance explains where the cyclones reside and the different numbers at each pole.

Magnetosphere

The Jovian magnetosphere is the region of space influenced by Jupiter's powerful magnetic field. It balloons 600,000 to 2 million miles (1 to 3 million kilometers) toward the Sun (seven to 21 times the diameter of Jupiter itself) and tapers into a tadpole-shaped tail extending more than 600 million miles (1 billion kilometers) behind Jupiter, as far as Saturn's orbit. Jupiter's enormous magnetic field is 16 to 54 times as powerful as that of the Earth. It rotates with the planet and sweeps up particles that have an electric charge. Near the planet, the magnetic field traps swarms of charged particles and accelerates them to very high energies, creating intense radiation that bombards the innermost moons and can damage spacecraft.

Jupiter's magnetic field also causes some of the solar system's most spectacular aurorae at the planet's poles.

• NASA Planetary Photojournal - Jupiter
• Planetary Rings Node
• NASA's Juno Mission

We have completed maintenance on Astronomy.com and action may be required on your account. Learn More

• Login/Register
• Solar System
• Exotic Objects
• Upcoming Events
• Deep-Sky Objects
• Observing Basics
• Telescopes and Equipment
• Astrophotography
• Space Exploration
• Human Spaceflight
• Robotic Spaceflight
• The Magazine

What has the Juno spacecraft taught us about Jupiter?

Untangle the mysteries of our solar system’s planets and moons. Check out Astronomy ’s free downloadable eBook, The Hitchhiker’s Guide to Planets , which contains everything you need to know about our solar systems major players. “Jupiter is central to understanding how planets in our solar system formed,” writes Caltech planetary scientist David Stevenson in the May Annual Review of Earth and Planetary Sciences . “And it has secrets still to be unlocked.”

With a little over a year left in the probe’s primary mission, Juno scientists are busy trying to understand how all the intriguing disparate discoveries mesh into a coherent picture of Jupiter’s inner life . The primary mission is scheduled to last until July 2021, though the team hopes to extend Juno’s visit for a few more years beyond that.

Meanwhile, here are four of Juno’s greatest hits to date.

Polar cyclone party

Juno is justly famous for its surreal photos of Jupiter’s swirling cloudscapes. But while the probe does have an excellent camera, not to mention a fanbase of amateur Jupiter enthusiasts ready to transform its images into science art, what makes these photos truly unique is Juno’s highly elongated, 53-day orbit: a trajectory that maximizes the spacecraft’s science potential while minimizing its exposure to Jupiter’s fierce radiation belts.

Around the planet’s south pole, Juno spied five cyclones, each wider than the United States, parked around a central cyclone of the same size. Not to be outdone, the north pole revealed eight similar cyclones encircling their own polar vortex. Remarkably, the storms didn’t seem to be going anywhere. With each of Juno’s flybys, the storms stayed put.

Complexity under the clouds

Because Jupiter is what astronomers call a gas giant planet, there is no point asking what conditions are like on its surface: It doesn’t have one. Instead, the hydrogen and helium gas that make up the bulk of Jupiter’s atmosphere simply get denser and denser the farther down you go, until the hydrogen becomes a liquid metal.

But there is still plenty of action in Jupiter’s swirling clouds, which are thought to be a mix of water and ammonia. And, as researchers have discovered via a microwave instrument that lets Juno probe beneath the clouds, there is plenty of complexity underneath as well.

And then there is the case of the missing ammonia. “We had assumed … that as soon as you drop below the [clouds], everything ought to be well mixed,” says mission lead Scott Bolton, a planetary scientist at Southwest Research Institute in San Antonio, Texas. Jupiter is, after all, a rapidly spinning ball of fluid (a day lasts just under 10 hours). But Juno’s microwave readings show that this mixing picture holds true only near the equator. It falls apart as you move north or south into Jupiter’s midlatitudes, where there is nowhere near as much ammonia as researchers expected.

To see why, Tristan Guillot, a planetary scientist at Côte d’Azur Observatory in France, and others developed computer models of Jupiter’s atmosphere and found that, away from the equator, ammonia might readily dissolve into water ice particles lofted up from below . This would reduce the amount of ammonia gas in these areas. It also means that the weather in Jupiter’s midlatitudes may feature hail-like storms of ammonia-soaked “mushballs” : frozen nuggets of roughly one part ammonia and two parts water.

A humongous smeared-out center

Although Jupiter doesn’t have a surface, researchers had a running argument before Juno’s arrival as to whether the planet had a core — a solid ball of heavier elements gathered at the planet’s center. They could argue it either way. In one common tale of Jupiter’s birth, rocky debris slowly coalesced into a solid mass up to 10 times as hefty as Earth. The gravity of that mass then hoovered up all the gas in its vicinity, surrounding itself with the deep hydrogen-helium atmosphere we see today. But in a different origin story, a pocket of gas swirling around the infant sun collapsed in on itself, creating a more-or-less pure hydrogen-helium world without a rocky core.

Hybrid magnetism

Jupiter’s huge fuzzy core undoubtedly has implications for other aspects of the planet’s behavior — one of them being the planet’s unusual, contorted magnetic field.

For decades, the textbook picture of the Jovian magnetic field was that it resembled Earth’s — which is to say that it looked like the field of a really big bar magnet, with a well-defined magnetic north pole on one end and a well-defined south pole on the other. Quick peeks from earlier spacecraft seemed to confirm that picture.

But the textbooks were wrong. Juno’s measurements show that the magnetic field in Jupiter’s northern hemisphere looks completely different from its southern counterpart . It’s as if someone took a bar magnet, bent it almost in half, frayed one end, split the other end, and then stuck the whole thing in the planet at a cockeyed angle. In the north is the frayed end: Rather than emerging around one central spot, the magnetic field sprouts like weeds along a long high-latitude band. In the south is the split end: Some of the field plunges back into the planet around the south pole while some is concentrated in a spot just south of the equator.

This magnetic field geometry is not seen anywhere else in the solar system. The southern hemisphere resembles Earth’s field, which scientists call dipolar (because it has two poles). The north has more in common with Uranus and Neptune, where the fields are more complex.

“It was weird to have essentially … one hemisphere Earth and one hemisphere Uranus and Neptune,” says Kimberly Moore, a Caltech astrophysicist and a lead author of several studies of Juno’s magnetic findings.

Planetary magnetic fields are generated by electrically conductive fluids in their interior. The unusual fields at Uranus and Neptune may be due to these fluids being restricted to a thinner region of the planet, relative to their size. Something similar might be happening at Jupiter thanks to its dilute core, says Moore. The north-south dichotomy may also emerge from all this complexity.

“That can really change the geometry of the patterns you can come up with,” she says. But that’s just one idea. Helium rain might also wreak havoc on the magnetic field, as could penetrating winds.

Giant distinctions

If Juno has taught us nothing else, it’s that no two giant planets are alike. At first glance, Jupiter has a lot in common with Saturn, for example. But despite both being big balls of mostly hydrogen and helium, they’ve gone down quite different paths.

Jupiter has conga lines of polar cyclones; Saturn has just one vortex per pole (one of which is six-sided!). Jupiter’s magnetic field is a hodge-podge; Saturn’s is pretty boring. Jupiter’s atmosphere is multicolored and banded; Saturn’s is relatively unblemished.

“Giant planets must come in different flavors,” Bolton says. “We need to understand that if we’re going to understand them in general, because the same physics must dictate everything.”

10.1146/knowable-060420-1

Trained as an astronomer, Christopher Crockett is a freelance science journalist living in Arlington, Virginia. His closest run-in with Jupiter was when he got to peer at it through the gigantic 2.7-meter telescope at McDonald Observatory in Texas. The view must have resembled what Juno saw during its final approach. He can be reached at [email protected] .

This article originally appeared in Knowable Magazine , an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter .

Could we find Planet Nine using JWST?

A visit to the cutting-edge Southwest Research Institute

A solar storm the size of the Carrington Event could knock out the backbone of the Internet

Dream Chaser spaceplane completes tests at NASA’s Neil Armstrong facility

What Is Polaris Dawn? The upcoming SpaceX mission, explained

WASP-69b — and its weird tail — help us understand the cosmos

At last! JWST finds signs of a thick atmosphere around a rocky exoplanet

Possible hints of life found on exoplanet K2-18b – how excited should we be?

Boeing’s Starliner launch – delayed again – will be an important milestone for commercial spaceflight

Suggested Searches

• Climate Change
• Expedition 64
• Mars perseverance
• SpaceX Crew-2
• International Space Station
• View All Topics A-Z

Humans in Space

Earth & climate, the solar system, the universe, aeronautics, learning resources, news & events.

NASA Invites Social Creators for Launch of NOAA Weather Satellite 

NASA’s New Mobile Launcher Stacks Up for Future Artemis Missions 

NASA’s Webb Hints at Possible Atmosphere Surrounding Rocky Exoplanet

• Search All NASA Missions
• A to Z List of Missions
• Upcoming Launches and Landings
• Spaceships and Rockets
• Communicating with Missions
• James Webb Space Telescope
• Hubble Space Telescope
• Why Go to Space
• Astronauts Home
• Commercial Space
• Destinations
• Living in Space
• Explore Earth Science
• Earth, Our Planet
• Earth Science in Action
• Earth Multimedia
• Earth Science Researchers
• Pluto & Dwarf Planets
• Asteroids, Comets & Meteors
• The Kuiper Belt
• The Oort Cloud
• Skywatching
• The Search for Life in the Universe
• Black Holes
• The Big Bang
• Dark Energy & Dark Matter
• Earth Science
• Planetary Science
• Astrophysics & Space Science
• The Sun & Heliophysics
• Biological & Physical Sciences
• Lunar Science
• Citizen Science
• Astromaterials
• Aeronautics Research
• Human Space Travel Research
• Science in the Air
• NASA Aircraft
• Flight Innovation
• Supersonic Flight
• Air Traffic Solutions
• Green Aviation Tech
• Drones & You
• Technology Transfer & Spinoffs
• Space Travel Technology
• Technology Living in Space
• Manufacturing and Materials
• Science Instruments
• For Kids and Students
• For Educators
• For Colleges and Universities
• For Professionals
• Science for Everyone
• Requests for Exhibits, Artifacts, or Speakers
• STEM Engagement at NASA
• NASA's Impacts
• Centers and Facilities
• Directorates
• Organizations
• People of NASA
• Internships
• Our History
• Doing Business with NASA
• Get Involved
• Aeronáutica
• Ciencias Terrestres
• Sistema Solar
• All NASA News
• Video Series on NASA+
• Newsletters
• Social Media
• Media Resources
• Upcoming Launches & Landings
• Virtual Events
• Sounds and Ringtones
• Interactives
• STEM Multimedia

Station Science 101 | Research in Microgravity: Higher, Faster, Longer

15 Years Ago: STS-125, the Final Hubble Servicing Mission

NASA Mission Strengthens 40-Year Friendship 

NASA Selects Commercial Service Studies to Enable Mars Robotic Science

Meet NASA Women Behind World’s Largest Flying Laboratory

International SWOT Mission Can Improve Flood Prediction

NASA Is Helping Protect Tigers, Jaguars, and Elephants. Here’s How.

C.26 Rapid Mission Design Studies for Mars Sample Return Correction and Other Documents Posted

NASA Selects Students for Europa Clipper Intern Program

The Big Event, 2024

Hubble Glimpses a Star-Forming Factory

NASA Images Help Explain Eating Habits of Massive Black Hole

Hubble Celebrates the 15th Anniversary of Servicing Mission 4

NASA Licenses 3D-Printable Superalloy to Benefit US Economy

ARMD Solicitations

Tech Today: A NASA-Inspired Bike Helmet with Aerodynamics of a Jet  

Tech Today: NASA’s Ion Thruster Knowhow Keeps Satellites Flying

Latest Join Artemis News and Features

NASA Challenge Gives Artemis Generation Coders a Chance to Shine

NASA Community College Aerospace Scholars

Johnson Celebrates AA and NHPI Heritage Month: Kimia Seyedmadani

20 Years Ago: NASA Selects its 19th Group of Astronauts

Diez maneras en que los estudiantes pueden prepararse para ser astronautas

Astronauta de la NASA Marcos Berríos

Resultados científicos revolucionarios en la estación espacial de 2023

410 years ago: galileo discovers jupiter’s moons, johnson space center.

Peering through his newly-improved 20-power homemade telescope at the planet Jupiter on Jan. 7, 1610, Italian astronomer Galileo Galilei noticed three other points of light near the planet, at first believing them to be distant stars. Observing them over several nights, he noted that they appeared to move in the wrong direction with regard to the background stars and they remained in Jupiter’s proximity but changed their positions relative to one another. He later observed a fourth star near the planet with the same unusual behavior. By Jan. 15, Galileo correctly concluded that they were not stars at all but moons orbiting around Jupiter, providing strong evidence for the Copernican theory that most celestial objects did not revolve around the Earth. In March 1610, Galileo published his discoveries of Jupiter’s satellites and other celestial observations in a book titled Siderius Nuncius (The Starry Messenger) .

As their discoverer, Galileo had naming rights to Jupiter’s satellites. He proposed to name them after his patrons the Medicis and astronomers called them the Medicean Stars through much of the seventeenth century, although in his own notes Galileo referred to them by the Roman numerals I, II, III, and IV, in order of their distance from Jupiter. Astronomers still refer to the four moons as the Galilean satellites in honor of their discoverer. The German astronomer Johannes Kepler suggested naming the satellites after mythological figures associated with Jupiter, namely Io, Europa, Ganymede, and Callisto, but his idea didn’t catch on for more than 200 years. Scientists didn’t discover any more satellites around Jupiter until American astronomer E.E. Barnard found Jupiter’s fifth moon Amalthea in 1892, much smaller than the Galilean moons and orbiting closer to the planet than Io. It was the last satellite in the solar system found by visual observation – all subsequent discoveries occurred via photography or digital imaging. As of today, astronomers have identified 79 satellites orbiting Jupiter.

Although each of the Galilean satellites has unique features, such as the volcanoes of Io, the heavily cratered surface of Callisto, and the magnetic field of Ganymede, scientists have focused more attention on Europa due to the tantalizing possibility that it might be hospitable to life. In the 1970s, NASA’s Pioneer 10 and 11 and Voyager 1 and 2 spacecraft took ever increasingly detailed images of the large satellites including Europa during their flybys of Jupiter. The photographs revealed Europa to have the smoothest surface of any object in the solar system, indicating a relatively young crust, and also one of the brightest of any satellite indicating a highly reflective surface. These features led scientists to hypothesize that Europa is covered by an icy crust floating on a subsurface salty ocean. They further postulated that tidal heating caused by Jupiter’s gravity reforms the surface ice layer in cycles of melting and freezing. 

More detailed observations from NASA’s Galileo spacecraft that orbited Jupiter between 1995 and 2003 and completed 11 close encounters with Europa revealed that long linear features on its surface may indicate tidal or tectonic activity. Reddish-brown material along the fissures and in splotches elsewhere on the surface may contain salts and sulfur compounds transported from below the crust and modified by radiation. Observations from the Hubble Space Telescope and re-analysis of images from Galileo revealed possible plumes emanating from beneath Europa’s crust, lending credence to that hypothesis. While the exact composition of this material is not known, it likely holds clues to whether Europa may be hospitable to life. 

Future robotic explorers of Europa may answer some of the outstanding questions about this unique satellite of Jupiter. Set for launch in 2025, NASA’s planned Europa Clipper mission will enter orbit around Jupiter and conduct 45 flybys of Europa during its 3.5-year mission. Managed by the Jet Propulsion Laboratory in Pasadena, California, and the Applied Physics Laboratory at Johns Hopkins University in Baltimore, Maryland, Europa Clipper will carry nine instruments including imaging systems and a radar to better understand the structure of the icy crust. Although the European Space Agency’s JUICE (Jupiter Icy Moon Explorer) spacecraft’s main goal will be to enter orbit around Ganymede in the 2020s, it also plans to conduct studies of Europa complementary with Europa Clipper’s. The two spacecraft should greatly increase our understanding of Europa.

• Ask An Astrobiologist
• Resources Graphic Histories Coloring Pages Heroes Posters Life in the extremes Digital Backgrounds SciComm Guild

Jupiter's "Grand Tack" Reshaped the Solar System

Jupiter, long settled in its position as the fifth planet from our sun, was a rolling stone in its youth. Over the eons, the giant planet roamed toward the center of the solar system and back out again, at one point moving in about as close as Mars is now. The planet’s travels profoundly influenced the solar system, changing the nature of the asteroid belt and making Mars smaller than it should have been. These details are based on a new model of the early solar system developed by NAI scientists at the Virtual Planetary Laboratory, the Goddard Center for Astrobiology, and their colleagues. Their paper appears in a recent issue of Nature.

“We refer to Jupiter’s path as the Grand Tack, because the big theme in this work is Jupiter migrating toward the sun and then stopping, turning around, and migrating back outward,” says the paper’s first author, Kevin Walsh of the Southwest Research Institute in Boulder, Colo. “This change in direction is like the course that a sailboat takes when it tacks around a buoy.”

According to the new model, Jupiter formed in a region of space about three-and-a-half times as far from the sun as Earth is (3.5 astronomical units). Because a huge amount of gas still swirled around the sun back then, the giant planet got caught in the currents of flowing gas and started to get pulled toward the sun. Jupiter spiraled slowly inward until it settled at a distance of about 1.5 astronomical units—about where Mars is now. (Mars was not there yet.)

“We theorize that Jupiter stopped migrating toward the sun because of Saturn,” says Avi Mandell, a planetary scientist at NASA Goddard and a co-author on the paper. The other co-authors are Alessandro Morbidelli at the Observatoire de la Cote d’Azur in Nice, France; Sean Raymond at the Observatoire de Bordeaux in France; and David O’Brien at the Planetary Science Institute in Tucson, Ariz.

Like Jupiter, Saturn got drawn toward the sun shortly after it formed, and the model holds that once the two massive planets came close enough to each other, their fates became permanently linked. Gradually, all the gas in between the two planets got expelled, bringing their sun-bound death spiral to a halt and eventually reversing the direction of their motion. The two planets journeyed outward together until Jupiter reached its current position at 5.2 astronomical units and Saturn came to rest at about 7 astronomical units. (Later, other forces pushed Saturn out to 9.5 astronomical units, where it is today.)

The effects of these movements, which took hundreds of thousands to millions of years, were extraordinary.

Jupiter’s Do-Si-Do

“Jupiter migrating in and then all the way back out again can solve the long-standing mystery of why the asteroid belt is made up of both dry, rocky objects and icy objects,” Mandell says.

Astronomers think that the asteroid belt exists because Jupiter’s gravity prevented the rocky material there from coming together to form a planet; instead, the zone remained a loose collection of objects. Some scientists previously considered the possibility that Jupiter could have moved close to the sun at some point, but this presented a major problem: Jupiter was expected to scatter the material in the asteroid belt so much that the belt would no longer exist.

“For a long time, that idea limited what we imagined Jupiter could have done,” Walsh notes.

Rather than having Jupiter destroy the asteroid belt as it moved toward the sun, the Grand Tack model has Jupiter perturbing the objects and pushing the whole zone farther out. “Jupiter’s migration process was slow,” explains Mandell, “so when it neared the asteroid belt, it was not a violent collision but more of a do-si-do, with Jupiter deflecting the objects and essentially switching places with the asteroid belt.”

In the same way, as Jupiter moved away from the sun, the planet nudged the asteroid belt back inward and into its familiar location between the modern orbits of Mars and Jupiter. And because Jupiter traveled much farther out than it had been before, it reached the region of space where icy objects are found. The massive planet deflected some of these icy objects toward the sun and into the asteroid belt.

“The end result is that the asteroid belt has rocky objects from the inner solar system and icy objects from the outer solar system,” says Walsh. “Our model puts the right material in the right places, for what we see in the asteroid belt today.”

Poor Little Mars

The time that Jupiter spent in the inner solar system had another major effect: its presence made Mars smaller than it otherwise would have been. “Why Mars is so small has been the unsolvable problem in the formation of our solar system,” says Mandell. “It was the team’s initial motivation for developing a new model of the formation of the solar system.”

Because Mars formed farther out than Venus and Earth, it had more raw materials to draw on and should be larger than Venus and Earth. Instead, it’s smaller. “For planetary scientists, this never made sense,” Mandell adds.

But if, as the Grand Tack model suggests, Jupiter spent some time parked in the inner solar system, it would have scattered some material available for making planets. Much of the material past about 1 astronomical unit would have been dispersed, leaving poor Mars out at 1.5 astronomical units with slim pickings. Earth and Venus, however, would have formed in the region richest in planet-making material.

“With the Grand Tack model, we actually set out to explain the formation of a small Mars, and in doing so, we had to account for the asteroid belt,” says Walsh. “To our surprise, the model’s explanation of the asteroid belt became one of the nicest results and helps us understand that region better than we did before.”

Another bonus is that the new model puts Jupiter, Saturn, and the other giant planets in positions that fit very well with the “Nice model,” a relatively new theory that explains the movements of these large planets later in the solar system’s history.

The Grand Tack also makes our solar system very much like the other planetary systems that have been found so far. In many of those cases, enormous gas-giant planets called “hot Jupiters” sit extremely close to their host stars, much closer than Mercury is to the sun. For planetary scientists, this newfound likeness is comforting.

“Knowing that our own planets moved around a lot in the past makes our solar system much more like our neighbors than we previously thought,” says Walsh. “We’re not an outlier anymore.”

Elizabeth Zubritsky NASA Goddard Space Flight Center

• About the Hub
• Announcements
• Faculty Experts Guide
• Subscribe to the newsletter

Explore by Topic

• Arts+Culture
• Politics+Society
• Science+Technology
• Student Life
• University News
• Voices+Opinion
• About Hub at Work
• Gazette Archive
• Benefits+Perks
• Health+Well-Being
• Current Issue
• About the Magazine
• Past Issues
• Support Johns Hopkins Magazine
• Subscribe to the Magazine

You are using an outdated browser. Please upgrade your browser to improve your experience.

Credit: Getty Images

New clues suggest how hot Jupiters form

Johns hopkins astronomers discover new way of determining the relative age of exoplanets and prove there are multiple ways these planets form.

By Laura Cech

Since the first hot Jupiter was discovered in 1995, astronomers have been trying to figure out how the searing-hot exoplanets formed and arrived in their extreme orbits. Johns Hopkins University astronomers have found a way to determine the relative age of hot Jupiters using new measurements from the Gaia spacecraft, which is tracking more than a billion stars.

Lead author Jacob Hamer, a PhD student in the Department of Physics and Astronomy at the Johns Hopkins Krieger School of Arts and Sciences, will present the findings this week at 1:15 p.m. on June 13 at the American Astronomical Society conference, which will be livestreamed . The work is set to be published be in Astronomical Journal .

Called hot Jupiters because the first one discovered was about the same size and shape as our solar system's Jupiter, these planets are about 20 times closer to their stars than Earth is to the sun, causing these planets to reach temperatures of thousands of degrees Celsius. Existing theories of planet formation could not explain these planets, so scientists came up with several ideas for how hot Jupiters might form. Initially, scientists proposed that hot Jupiters could form further out, like Jupiter, and then migrate to their present locations due to interactions with their host star's disk of gas and dust. Or it could be that they form further out and then migrate in much later—after the disk is gone—through a more violent and extreme process called high-eccentricity migration.

"The question of how these exoplanets form and get to their present orbits is literally the oldest question in our subfield and it is something that thousands of astronomers have been struggling to answer for more than 25 years," said co-author Kevin Schlaufman , an assistant professor who works at the intersection of galactic astronomy and exoplanets.

Image caption: The different formation processes for hot Jupiters affect the alignment of their velocities and orbits as they age

Image credit : Courtesy of Jacob Hamer

Some hot Jupiters have orbits that are well-aligned to their star's rotation, like the planets in our solar system. Others have orbits misaligned from the equators of their stars. Scientists weren't able to prove whether the different configurations were a product of a different formation process, or a single formation process followed by tidal interactions between the planets and the stars. "Without this really precise method of measuring ages, there was always missing information," said Hamer.

Hamer is one of the first astronomers to use the new data from the Gaia satellite to study the ages of exoplanet systems to figure out how they form and evolve.  Being able to determine the velocities—the directional speed—of the stars was key in determining their age. When stars are born, they move similarly to one another within the galaxy. As those stars age, their velocities become more and more different, Hamer said. With this new method, Hamer proved that there are multiple ways that hot Jupiters form.

"One [formation process] occurs quickly and produces aligned systems, and [the other] occurs over longer timescales and produces misaligned systems," said Hamer. "My results also suggest that in some systems with less massive host stars, tidal interactions allow the hot Jupiters to realign the axis of their host star's rotation to be aligned with their orbit."

New data from ground- and space-based telescopes are helping scientists learn more about exoplanets. In April, teams of astronomers, including some from Johns Hopkins, reported findings about the atmospheres of ultra-hot Jupiters made possible using observations from the Hubble Space Telescope.

Posted in Science+Technology , Student Life

Tagged astronomy , physics and astronomy , outer space , space@hopkins

Related Content

Atmospheric mixology

You might also like, news network.

• Johns Hopkins Magazine
• Get Email Updates
• Submit an Announcement
• Submit an Event
• Privacy Statement
• Accessibility

Discover JHU

• About the University
• Schools & Divisions
• Academic Programs
• Plan a Visit
• my.JohnsHopkins.edu
• © 2024 Johns Hopkins University . All rights reserved.
• University Communications
• 3910 Keswick Rd., Suite N2600, Baltimore, MD
• X Facebook LinkedIn YouTube Instagram

March 25, 2024

11 min read

Bizarre ‘Hot Jupiter’ Planets Keep Surprising Astronomers

Astronomers now have three possible theories to explain how weird hot Jupiter exoplanets form

By Juliette Becker

Artist's representation of the WASP-47 planetary system.

It was May 2013, and the Kepler space telescope was dead .

The Kepler planet-hunting mission had been discovering new planets since its launch in 2009, but in May 2013 the second of its four reaction wheels failed. The telescope could no longer control where it pointed; the prime Kepler mission was over.

At the time, I was a third-year undergraduate student at the California Institute of Technology, and it seemed to me that the death of the Kepler mission also signified the death of the goals I had spent the last three years developing. I wanted to study new exoplanet systems and determine what they can tell us about how their planets formed. It seemed to be a great time to be starting in the field—the Kepler space telescope had ushered in a new era of exoplanet discovery, and new planets kept pouring in . The possibilities and opportunities felt endless. Eventually, I was sure, all these discoveries would lead to a unified theory of planet formation, and I wanted to help solve that puzzle using the pieces Kepler was finding.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

But without Kepler, the stream of discoveries that had seemed endless only months before seemed to evaporate. I was devastated.

I wouldn’t know for several more years that I was completely wrong about what the death of Kepler meant. The broken telescope was not an end but a new beginning, and it would lead to a transformation in our understanding of a fascinating and mysterious category of planets called hot Jupiters .

The story of hot Jupiters began decades ago. Even before astronomers had developed the technology to be able to look for planets around other stars, scientists imagined what those planets might be like. In 1952 Ukraine-born American astronomer Otto Struve published a short paper suggesting that planets the mass of Jupiter could theoretically reside 50 times closer to their host star than Earth is to the sun. If they did reside so close to their star, he mused, then they should be discoverable in one of two ways: either by monitoring the motion of the host star and looking for its slight reflexive velocity caused by the gravitational tug of an orbiting planet; or by monitoring the star’s brightness and looking for dips in starlight that would occur when a planet passed in front of the star. These two methods, referred to as the radial velocity and transit techniques, respectively, could both theoretically find Jupiter-mass planets orbiting near their star. At the time Struve made this prediction, no one had the technology to test the idea.

But scientists were skeptical, both of the idea that Jupiter-size planets might orbit so close to their sun and the notion that they’d ever be able to detect exoplanets at all. Such large planets, prevailing theories explained, would form farther away, past a point in their planetary system called the ice line, where the growing planet could pull in mass from a large reservoir of icy disk material. As a result, most scientists expected exoplanets to look like the planets of our own solar system: small terrestrial planets would be interior to the ice line and large gas giants would be located beyond it. If this setup prevailed, then astronomers would have to gather data for years or even decades before they could make a discovery. Jupiter orbits the sun once every 12 years, so researchers might have to wait decades to see a Jupiter-like exoplanet move in front of its star. Though theoretically possible, this would be a Herculean task—and smaller terrestrial planets might provide signals too faint to detect.

This understanding shifted entirely in 1995, 43 years after Struve first pondered the possibility of alien Jupiters. That was when astronomers Michel Mayor and Didier Queloz announced the discovery via the radial velocity method of the first exoplanet to be found orbiting a regular star: 51 Pegasi b. This discovery would earn them the Nobel Prize in 2019. A planet about half the mass of Jupiter, 51 Peg b took only 4.2 days to complete one full orbit, and its orbit was only 10 times larger in diameter than the radius of its host star. This extremely short orbital period meant that previous concerns that decades would be needed to confirm an exoplanet orbit suddenly vanished. This planet’s unique combination of being extremely close to its star (and having a very high temperature as a result) and having a large mass (as big as Jupiter, the largest solar system planet) resulted in a signal strong enough to be detected by Mayor and Queloz, as well as a new nickname for this type of planet: “hot Jupiter .” This exoplanet looked like no planet that had ever been seen before, and its size and orbital distance placed it well outside the bounds of classic planet-formation theories.

Credit: Matthew Twombly

Immediately scientists began developing new theories on how this kind of planet could have formed. Planets the mass of Jupiter are significantly more massive than all other classes of planets and require a unique process to form. Jupiter-mass planets must first build a core out of rock and ice and then build a gaseous envelope large enough to start a process called runaway accretion, where they hoover up all nearby material and increase their mass 10-fold in less than a million years (a very short time compared to the lifetimes of planetary systems). Classic formation theories predicted that this process would take place far from the star, past the location where the ambient temperature is below the freezing point of water. Less than a year after the initial discovery of 51 Peg b, Doug Lin proposed a mechanism that could create hot Jupiters: Lin suggested that the planet formed past the ice line and then migrated inward after interactions with the protoplanetary disk—the material leftover after the star formed, from which planets are born. The timing of this mechanism made logical sense because Jupiter-sized planets would need to grow to their full girth while the disk is still present and then could make their way inward very efficiently after they were fully formed. This theory of dynamically quiet planet migration, called disk migration, unified the existence of this first hot Jupiter with traditional theories of planet formation because in this scenario, hot Jupiters would form identically to their cold counterparts but would simply move later. Yet the mystery turned out to be a bit more complicated.

After the first planet was found, the race was on to discover more.

After the year 2000, a series of ground-based telescope networks began to emerge, designed to search systematically for more planets like 51 Peg b and another hot Jupiter found early on, HD 209458 b. Soon hot Jupiters became the most plentiful type of planet known by far, though scientists understood that this was because of the ease of finding them and did not necessarily reflect how prevalent they truly were. The big, massive planets orbiting so close to their star gave particularly large signals both in radial velocities (because a massive, close-in planet will tug the star around more) and in transits (because a close-in planet has a higher probability of passing in front of the star from our line of sight and will block out more starlight because of its larger radius).

As time passed, scientists discovered dozens and then hundreds of planets that fit a relatively narrow profile: they had masses and radii similar to Jupiter’s, orbital periods of a few days and orbits that were perfectly or nearly perfectly circular. The similarity of these planets was remarkable, and it seemed to indicate that whatever processes produced these planets were similar across the variety of systems studied. The collection of known hot Jupiters, however, was limited by ground-based observational capabilities, which left open the possibility of many undiscovered aspects of these systems that would require alternative observational techniques to uncover.

Enter the Kepler space telescope. Launched in 2009, the observatory immediately changed the field. Whereas ground-based observations were limited to only the largest planets orbiting stars, Kepler’s precision could uncover much smaller planets. Soon after launch Kepler found its first multiplanet system, Kepler-9, in which two planets orbited the same star. Soon it had discovered hundreds and then thousands of planets.

By this point scientists had spotted so many hot Jupiters that large-scale demographics and population studies were starting to become possible. Initial estimates found that hot Jupiters likely orbited 0.1 percent of stars.

Multiplanet systems seemed to dominate in general, although a 2012 study used the available Kepler data to conclude that hot Jupiters tended not to have planetary siblings . There appeared to be something unique about hot Jupiters , providing a stark contrast to the picture that was developing of exoplanets in general.

A second, more recent theory of hot Jupiter formation called tidal migration could potentially explain the lack of these companions. In this newer, more violent, mechanism, a Jupiter-mass planet forms past the ice line in its system. After time has passed and the protoplanetary disk has dissipated, an interaction between the planet and another object (such as a passing star or another planet) causes the Jupiter’s orbit to become eccentric, or oblong. With an extremely eccentric orbit, the Jupiter will come close to its host star once per orbit. Each time it passes close to its star, the Jupiter will lose some of its orbital energy, making its orbit shrink and return to a circular shape over time. This process would be very destabilizing to any other planets within the Jupiter’s initial orbit, potentially evicting them from the planetary system, and would therefore naturally explain the lack of companions to hot Jupiters seen in the Kepler data. Because of its consistency with the new data, tidal migration became the preferred theory for hot Jupiter formation, supplanting the theory of disk migration first proposed to explain 51 Peg b.

All this success from Kepler shows why I and so many other scientists were dismayed when one of Kepler’s reaction wheels failed in July 2012 and another wheel failure followed in May 2013.

At first it seemed that all hope was lost, but following nearly a year of uncertainty, the Kepler team figured out a new way to operate the telescope that cleverly balanced the spacecraft using the pressure of stellar radiation. In its new incarnation, christened K2, the telescope could continue its search for exoplanets by surveying a new selection of stars every 90 days. Although the shorter observation baselines provided some limitations, the new observational fields also provided high-quality data on an almost unmanageable number of planet hosts. Every 90 days data from a different section of the sky would become available.

Every time a new field was downloaded from the spacecraft, I exchanged excited messages with my fellow researchers. Less than a year after the new mission began, K2 observed a field containing a star called WASP-47, the host of an apparently typical hot Jupiter discovered earlier. In July 2015, I exchanged messages with astronomer Andrew Vanderburg about a series of brand-new signals suggesting additional planets might be transiting in front of the star. Vanderburg had learned about the signals from Hans Martin Schwengeler, an amateur scientist in Switzerland. These new transits stopped me in my tracks. WASP-47 was a known hot Jupiter host—but the K2 light curve showed not just the one expected planet but two additional nearby planets as well. One of them was a Neptune-size planet orbiting just slightly exterior to the known hot Jupiter, and the other was a bit larger than Earth, orbiting interior to the hot Jupiter’s path.

For a moment, it was like my own reaction wheels had failed as my mind spun with the implications. Remember, the consensus in the field at that time was that hot Jupiters never had nearby planetary companions. Yet this beautiful system was a counterexample to that rule. If this hot Jupiter had migrated, its internal and external companions had both survived its journey!

In August 2015 we published our discovery of the new planets , including an analysis where we showed that even if the planets had not happened to transit the star, we still could have discovered one of them just by the gravitational tug it would exert on the hot Jupiter. Less than two days after announcing the planets publicly, I received an e-mail from French scientist Marion Neveu-VanMalle. She explained that her team had been monitoring the WASP-47 system using the radial velocity method and that they had found an additional fourth planet in the system—a cold Jupiter-mass planet, WASP-47 c, orbiting distantly from the inner three planets. Whatever migration process might have occurred must have allowed both the inner companions to the hot Jupiter to survive and also allowed the cold Jupiter companion to stay put in its distant orbit.

This discovery, combined with our discoveries and the original work by the WASP team, meant we now knew that the WASP-47 system contained an unprecedented geometry: it was the only hot Jupiter known to have nearby planetary companions, and there was a distant, colder Jupiter in the system as well. This setup showed that there was something lacking in our theories of hot Jupiter formation.

In 2016 astronomers Konstantin Batygin, Peter Bodenheimer and Greg Laughlin published a paper that suggested a third theory of how hot Jupiters come to be : a piecemeal mechanism they called in situ formation. In this scenario, a hot Jupiter forms in three steps. First, its rocky core builds up past the ice line out of cold disk material; then the core migrates inwards toward its final hot orbit; finally, the core accretes its massive gaseous envelope from disk material streaming by its location. Notably, this theory did predict that exterior companions to hot Jupiters should exist, which was consistent with the newly discovered planets in WASP-47.

After the WASP-47 surprise, astronomers were galvanized to look for more rule-breaking systems.

The next big step forward came following the 2018 launch of the Transiting Exoplanet Survey Satellite (TESS), which is designed to search the brightest stars across the entire sky for exoplanets. In 2020 I worked on a team led by astronomer Chelsea Huang to examine a star called TOI-1130 using TESS observations. We found that the system hosted a hot Jupiter with an interior planetary companion . In addition to that system, other teams found three more hot Jupiters with companions, bringing the total number of systems containing hot Jupiters with siblings to five.

These five systems, combined with the hundreds of systems where a hot Jupiter is known but there is no evidence of additional nearby planets, leave all three of the major formation theories as options: dynamically quiet disk migration, violent and destabilizing tidal migration and piecemeal in situ formation. Each of these three mechanisms seems feasible for a subset of the known population of hot Jupiters. Could it be that all three scenarios sometimes occur?

Despite initial impressions that hot Jupiters were a remarkably uniform population of planets with similar properties, it now seems likely that hot Jupiters with companions formed in a different way than the lonely hot Jupiters. During the next several years TESS should continue to find more systems containing hot Jupiters with companions, and the location and properties of those companions will help paint a more complete picture of the possible architectures of hot Jupiter systems.

The next step in fully understanding hot Jupiters is to use these discoveries to establish the relative likelihoods of the three possible migration mechanisms in order to determine which systems formed which way. Jupiter-sized planets are the rulers of their planetary system because of their dominant gravitational influence and the way their migration pathway sculpts the architectures of their system. Understanding these worlds is the first step to constructing a unified theory of planet formation that scientists have been seeking for centuries.

Space Facts

Jupiter Facts

Jupiter is the largest planet in the solar system and is the fifth planet out from the Sun . It is two and a half times more massive than all the other planets in the solar system combined. It is made primarily of gases and is therefore known as a “ gas giant ”.

Facts about Jupiter

• Jupiter is the fourth brightest object in the solar system. Only the Sun,  Moon  and  Venus  are brighter. It is one of five planets visible to the naked eye from Earth.
• The ancient Babylonians were the first to record their sightings of Jupiter. This was around the 7 th  or 8 th  century BC. Jupiter is named after the king of the Roman gods. To the Greeks, it represented Zeus, the god of thunder. The Mesopotamians saw Jupiter as the god Marduk and patron of the city of Babylon. Germanic tribes saw this planet as Donar, or Thor.
• Jupiter has the shortest day of all the planets. It turns on its axis once every 9 hours and 55 minutes. The rapid rotation flattens the planet slightly, giving it an oblate shape.
• Jupiter orbits the Sun once every 11.8 Earth years. From our point of view on  Earth , it appears to move slowly in the sky, taking months to move from one constellation to another.
• Jupiter has unique cloud features. The upper atmosphere of Jupiter is divided into cloud belts and zones. They are made primarily of ammonia crystals, sulfur, and mixtures of the two compounds.
• The Great Red Spot is a huge storm on Jupiter. It has raged for at least 350 years. It is so large that three Earths could fit inside it.
• Jupiter’s interior is made of rock, metal, and hydrogen compounds. Below Jupiter’s massive atmosphere (which is made primarily of hydrogen), there are layers of compressed hydrogen gas, liquid metallic hydrogen, and a core of ice, rock, and metals.
• Jupiter’s moon Ganymede is the largest moon in the solar system. Jupiter’s moons are sometimes called the Jovian satellites, the largest of these are Ganymeade, Callisto Io and Europa. Ganymeade measures 5,268 km across, making it larger than the planet  Mercury .
• Jupiter has a thin ring system. Its rings are composed mainly of dust particles ejected from some of Jupiter’s smaller worlds during impacts from incoming comets and asteroids. The  ring system  begins some 92,000 kilometres above Jupiter’s cloud tops and stretches out to more than 225,000 km from the planet. They are between 2,000 to 12,500 kilometres thick.
• Eight spacecraft have visited Jupiter. Pioneer 10 and 11, Voyager 1 and 2, Galileo, Cassini, Ulysses, and New Horizons missions. The Juno mission is its way to Jupiter and will arrive in July 2016. Other future missions may focus on the Jovian moons Europa, Ganymede, and Callisto, and their subsurface oceans.

Jupiter Diagrams

Jupiter’s Great Red Spot

Situated 22° south of Jupiter’s equator, the Great Red Spot is a storm that has been raging for at least 186 years. Upper estimates suggest the storm could have been in existence for over three and a half centuries.

The first observation of the Great Red Spot was in the seventeenth century, when telescopes first started to be used. However, it is unknown whether this is the same red spot that we see today, or whether Jupiter has had many such storms that have come and gone.

The red spot spins anticlockwise and takes six (Earth) days to rotate completely. Another mystery surrounding the red spot is what makes it red. Scientists have several theories, for instance, the presence of red organic compounds.

Jupiter’s Atmosphere

Jupiter’s atmosphere is the solar system’s largest planetary atmosphere. It is composed of hydrogen (90%) and helium (10%), in roughly the same proportions found in the Sun . It also contains much smaller amounts of other gases, such as ammonia, methane and water.

Sources: https://solarsystem.nasa.gov/planets/jupiter/overview/ , https://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html , https://www.planetary.org/multimedia/space-images/jupiter/20120906_jupiter_vgr1_global_caption.html First Published: June 2012 Last Updated: February 2020 Author: Chris Jones

Related space facts:

• Skip to Nav
• Skip to Main
• Skip to Footer

Hypothesis: Our Solar System Lacks 'Super-Earths' Because Jupiter Wrecked Them All

Please try again

I’ve always loathed Jupiter.

For one thing, I am not stoked on toxic gases or crushing gravity. And the weather on Jupiter is abysmal, with wind speeds roughly twice those of hurricanes on Earth.

Were I in charge, I once told a theoretical physicist at Vanderbilt University in Nashville, I would set about destroying Jupiter for the good of humanity. He reminded me that in 1994, a like-minded comet smashed into the gas giant, which is some 89,000 miles across. The result was like a bullet fired into a mountain of shaving cream, accomplishing nothing.

Sometimes when I am feeling crabby aboard an overly humid BART car with no vacant seats I think, “Well, of all the places in the universe that I could be right now, at least I’m not on Jupiter.”

I mention this to explain the vindication I feel upon learning that Jupiter may be the reason our solar system is, it’s turning out, something of a weirdo among its galactic peers. Scientists perusing thousands of exoplanets (some potentially habitable) in other systems around the Milky Way are discovering that rocky “super-Earths” are commonplace.

These are planets bigger than our own, albeit perhaps not better for our brand of life: they may have crushingly thick atmospheres, and their orbits are typically tighter than Mercury’s.

“The standard-issue planetary system in our galaxy seems to be a set of super-Earths with alarmingly short orbital periods. Our solar system is looking increasingly like an oddball,” says Gregory Laughlin , professor and chair of astronomy and astrophysics at University of California,  Santa Cruz, and co-author of a new paper in Proceedings of the National Academy of Sciences.

The reason our humble solar system suffers this peculiar dearth of “super-Earths” and must instead make do with our vanilla “ Earth -Earth” can be summarized thusly: Jupiter.

Like Miley Cyrus, Jupiter came in like a wrecking ball.

In 2011, astronomers proposed the “Grand Tack” hypothesis, suggesting that during the early days of the solar system — the first few million years — Jupiter migrated inward toward the sun, stopping only when the formation of Saturn tugged it back out to its current orbit.

Laughlin and co-author Konstantin Batygin think rocky planets could’ve been forming near our sun, until an encroaching Jupiter’s gravitational perturbations rudely started compressing their orbits, slinging them into each other in a chain reaction that took out any nascent super-Earths and sent a lot of debris spiraling into the sun to be vaporized.

“It’s the same thing we worry about if satellites were to be destroyed in low-Earth orbit. Their fragments would start smashing into other satellites and you’d risk a chain reaction of collisions,” Laughlin says. “Our work indicates that Jupiter would have created just such a collisional cascade in the inner solar system.”

A second generation of inner planets including familiar old Earth, as well as Mercury, Venus and Mars, would’ve emerged from the aftermath only tens of millions of years later. This explains why the planets close to our sun are younger than the planets farther away. And again, this was possible only thanks to Saturn tugging Jupiter away, thereby allowing our humble planet some breathing room to, you know, exist.

Thank you, Saturn.

To learn more about how we use your information, please read our privacy policy.

Hubble Finds a Planet Forming in an Unconventional Way

NASA's Hubble Space Telescope has directly photographed evidence of a Jupiter-like protoplanet forming through what researchers describe as an "intense and violent process." This discovery supports a long-debated theory for how planets like Jupiter form, called "disk instability."

Interpreting this system is extremely challenging. This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet.

Thayne Currie

Lead Researcher on the Study

The new world under construction is embedded in a protoplanetary disk of dust and gas with distinct spiral structure swirling around surrounding a young star that’s estimated to be around 2 million years old. That's about the age of our solar system when planet formation was underway. (The solar system's age is currently 4.6 billion years.)

"Nature is clever; it can produce planets in a range of different ways," said Thayne Currie of the Subaru Telescope and Eureka Scientific, lead researcher on the study.

All planets are made from material that originated in a circumstellar disk. The dominant theory for jovian planet formation is called "core accretion," a bottom-up approach where planets embedded in the disk grow from small objects – with sizes ranging from dust grains to boulders – colliding and sticking together as they orbit a star. This core then slowly accumulates gas from the disk. In contrast, the disk instability approach is a top-down model where as a massive disk around a star cools, gravity causes the disk to rapidly break up into one or more planet-mass fragments.

The newly forming planet, called AB Aurigae b, is probably about nine times more massive than Jupiter and orbits its host star at a whopping distance of 8.6 billion miles – over two times farther than Pluto is from our Sun. At that distance it would take a very long time, if ever, for a Jupiter-sized planet to form by core accretion. This leads researchers to conclude that the disk instability has enabled this planet to form at such a great distance. And, it is in a striking contrast to expectations of planet formation by the widely accepted core accretion model.

The new analysis combines data from two Hubble instruments: the Space Telescope Imaging Spectrograph and the Near Infrared Camera and Multi-Object Spectrograph. These data were compared to those from a state-of-the-art planet imaging instrument called SCExAO on Japan's 8.2-meter Subaru Telescope located at the summit of Mauna Kea, Hawaii. The wealth of data from space and ground-based telescopes proved critical, because distinguishing between infant planets and complex disk features unrelated to planets is very difficult.

"Interpreting this system is extremely challenging," Currie said. "This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet."

Nature itself also provided a helping hand: the vast disk of dust and gas swirling around the star AB Aurigae is tilted nearly face-on to our view from Earth.

Currie emphasized that Hubble's longevity played a particular role in helping researchers measure the protoplanet's orbit. He was originally very skeptical that AB Aurigae b was a planet. The archival data from Hubble, combined with imaging from Subaru, proved to be a turning point in changing his mind.

"We could not detect this motion on the order of a year or two years," Currie said. "Hubble provided a time baseline, combined with Subaru data, of 13 years, which was sufficient to be able to detect orbital motion."

"This result leverages ground and space observations and we get to go back in time with Hubble archival observations," Olivier Guyon of the University of Arizona, Tucson, and Subaru Telescope, Hawaii added. "AB Aurigae b has now been looked at in multiple wavelengths, and a consistent picture has emerged – one that's very solid."

The team's results are published in the April 4 issue of Nature Astronomy .

"This new discovery is strong evidence that some gas giant planets can form by the disk instability mechanism," Alan Boss of the Carnegie Institution of Science in Washington, D.C. emphasized. "In the end, gravity is all that counts, as the leftovers of the star-formation process will end up being pulled together by gravity to form planets, one way or the other."

Understanding the early days of the formation of Jupiter-like planets provides astronomers with more context into the history of our own solar system. This discovery paves the way for future studies of the chemical make-up of protoplanetary disks like AB Aurigae, including with NASA's James Webb Space Telescope.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Media Contacts:

Claire Andreoli NASA's  Goddard Space Flight Center 301-286-1940

Hannah Braun Space Telescope Science Institute, Baltimore, Maryland

Ray Villard Space Telescope Science Institute, Baltimore, Maryland

Science Contacts:

Thayne Currie Subaru Telescope, Hilo, Hawaii Eureka Scientific Inc., Oakland, California

Olivier Guyon Subaru Telescope, Hilo, Hawaii University of Arizona, Tucson, Arizona

Kellen Lawson University of Oklahoma, Norman, Oklahoma

Related Terms

• Astrophysics
• Goddard Space Flight Center
• Hubble Space Telescope

Explore More

Hubble Celebrates the 15th Anniversary of Servicing Mission 4

Hubble Glimpses a Star-Forming Factory

NASA Images Help Explain Eating Habits of Massive Black Hole

Data from NASA’s retired Spitzer Space Telescope has given scientists new insights into why some supermassive black holes shine differently than others. In images from NASA’s retired Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the heart of the Andromeda galaxy. It turns out these streams […]

Discover More Topics From NASA

James Webb Space Telescope

Perseverance Rover

Parker Solar Probe

• Culinary Arts
• Hypothesis involving Jupiter

HINTS AND TIPS:

Before giving away the correct answer, here are some more hints and tips for you to guess the solution on your own!

1. The first letter of the answer is: G

2. the last letter of the answer is: k, 3. there are 2 vowels in the hidden word:.

CORRECT ANSWER :

Other Related Levels

If you successfully solved the above puzzle and are looking for other related puzzles from the same level then select any of the following:

• People toys made from husks
• Comic strip postpartum sadness
• People toys made from the straw harvest
• Toys balloons etc sold in circus stands
• The capital of Anguilla
• Americas great swimmer before Phelps
• Secret service agent who fancies a specific drink
• Utensil used to open preserved tin food
• __ Science belief system of young Marilyn Monroe
• It is bliss
• A newborn baby bird fresh from its egg
• Catching prawns
• Fast vessel on water
• Croaky-voiced emperor in Star Wars films
• They are all for monarchic rule
• Hell but for a limited time
• Agent 007 who always orders a martini

If you already solved this clue and are looking for other clues from the same puzzle then head over to CodyCross Culinary Arts Group 135 Puzzle 4 Answers .

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• 08 May 2024

‘Milestone’ discovery as JWST confirms atmosphere on an Earth-like exoplanet

• Sumeet Kulkarni

You can also search for this author in PubMed   Google Scholar

The planet 55 Cancri e (artist’s impression) orbits very close to its star. Credit: Mark Garlick/Science Photo Library

Astronomers say that they have used the James Webb Space Telescope (JWST) to detect for the first time an atmosphere surrounding a rocky planet outside the Solar System 1 . Although this planet cannot support life as we know it, in part because it is probably covered by a magma ocean, scientists might learn something from it about the early history of Earth — which is also a rocky planet and was once molten.

Finding a gaseous envelope around an Earth-like planet is a big milestone in exoplanet research, says Sara Seager, a planetary scientist at the Massachusetts Institute of Technology in Cambridge who was not involved with the research. Earth’s thin atmosphere is crucial for sustaining life, and being able to spot atmospheres on similar terrestrial planets is an important step in the search for life beyond the Solar System.

The planet investigated by JWST, called 55 Cancri e, orbits a Sun-like star 12.6 parsecs away and is considered a super-Earth, a terrestrial planet a little bigger than Earth — in this case, with about twice Earth’s radius and more than eight times as heavy. According to a paper published today in Nature 1 , its atmosphere is probably rich in carbon dioxide or carbon monoxide and has a thickness that is “up to a few per cent” of the planet’s radius.

A mysterious planet

Another reason that 55 Cancri e is uninhabitable is that it is very close to its star — around one sixty-fifth of the distance from Earth to the Sun. And yet, “it’s perhaps the most studied rocky planet”, says Aaron Bello-Arufe, an astrophysicist at the Jet Propulsion Laboratory (JPL) in Pasadena, California, and a co-author of the paper. Its host star is bright in our night sky, and because it is large for a rocky planet, it’s easier to study than other planets outside the Solar System. “Every telescope or instrument that you can think of in astronomy has pointed to this planet at some point,” Bello-Arufe says.

55 Cancri e was so well studied that after JWST launched in December 2021 , engineers pointed the observatory’s infrared spectrometers towards it for testing. These instruments can detect the chemical fingerprints of gases swirling around planets as they absorb infrared wavelengths from starlight. Bello-Arufe and his colleagues then decided to dig deeper to confirm whether the planet had an atmosphere.

Before the latest observations, astronomers had changed their minds about 55 Cancri e myriad times. The planet was discovered in 2004 2 . At first, researchers thought it was probably the core of a gas giant similar to Jupiter. But in 2011, the Spitzer Space Telescope observed the planet as it passed in front of its star 3 , and researchers found that 55 Cancri e is in fact a lot smaller and denser than a gas giant, making it a rocky super-Earth.

55 Cancri e is a little bigger than Earth, but much smaller than the Solar System’s giant planets, such as Neptune. Credit: NASA, ESA, CSA, Dani Player (STScI)

Some years later, researchers noticed that 55 Cancri e was cooler than it should have been for a planet so close to its star, indicating that it probably has an atmosphere 4 . One hypothesis was that the planet is a ‘water world’ enveloped by supercritical water molecules; another was that it is surrounded by an expansive, primordial atmosphere composed mainly of hydrogen and helium 5 . But these ideas were eventually disproved.

A planet so close to its star would be bombarded by stellar winds and have a hard time holding on to volatile molecules in its atmosphere, says Renyu Hu, a planetary scientist at JPL and a co-author of the latest study. Two possibilities remained, he says. The first was that the planet is completely dry, with an ultrathin atmosphere of vaporized rock. The second was that it has a thick atmosphere composed of heavier, volatile molecules that do not bleed away easily.

A clearer picture

The latest data indicate that 55 Cancri e’s atmosphere contains carbon-based gases, pointing to option two. The team collected bona fide evidence of an atmosphere, Seager says, but more observations are needed to determine its full composition, the relative quantities of gases present and its precise thickness.

Laura Schaefer, a planetary geologist at Stanford University in California, is interested in learning how 55 Cancri e’s atmosphere interacts with materials beneath the planet’s surface. It’s still possible that the atmosphere is being eroded by stellar winds, the study’s authors say, but the gases could be getting replenished by the melting and outgassing of rocks in the magma ocean.

“Earth probably went through at least one magma-ocean stage, maybe several,” Schaefer says. “Having actual present-day examples of magma oceans can help us understand the early history of our Solar System.”

doi: https://doi.org/10.1038/d41586-024-01332-w

Hu, R. et al. Nature https://doi.org/10.1038/s41586-024-07432-x (2024).

Article   Google Scholar  

McArthur, B. E. et al. Astrophys. J. 614 , L81 (2004).

Demory, B.-O. et al. Astron. Astrophys. 533 , A114 (2011).

Tsiaras, A. et al. Astrophys. J. 820 , 99 (2016).

Gillon, M. et al. Astron. Astrophys. 539 , A28 (2012).

Download references

Reprints and permissions

Related Articles

• Planetary science
• Astronomy and astrophysics
• Astronomical instrumentation

A secondary atmosphere on the rocky Exoplanet 55 Cancri e

Article 08 MAY 24

Venus water loss is dominated by HCO+ dissociative recombination

Article 06 MAY 24

China’s Chang’e-6 launched successfully — what happens next?

News 06 MAY 24

Dazzling auroras are just a warm-up as more solar storms are likely, scientists say

News Explainer 13 MAY 24

‘Best view ever’: observatory will map Big Bang’s afterglow in new detail

News 22 MAR 24

Two giant US telescopes threatened by funding cap

News 29 FEB 24

The Dimorphos ejecta plume properties revealed by LICIACube

Article 28 FEB 24

Recruitment of Principal Investigators by the School of Life Sciences, Peking University

The School of Life Sciences at Peking University is actively seeking talents, with an emphasis on bioinformatics/computational biology/AI/RNA biology.

Beijing (CN)

School of Life Sciences, Peking University

2024 Recruitment notice Shenzhen Institute of Synthetic Biology: Shenzhen, China

The wide-ranging expertise drawing from technical, engineering or science professions...

Shenzhen,China

Shenzhen Institute of Synthetic Biology

Head of Operational Excellence

In this key position, you’ll be responsible for ensuring efficiency and quality in journal workflows through continuous improvement and innovation.

United States (US) - Remote

American Physical Society

Rowland Fellowship

The Rowland Institute at Harvard seeks outstanding early-career experimentalists in all fields of science and engineering.

Cambridge, Massachusetts

Rowland Institute at Harvard

Postdoctoral Fellowship: Chemical and Cell Biology

The 2-year fellowship within a project that will combine biochemical, cell biological and chemical genetic approaches to elucidate migrasome biology

Umeå, Sweden

Umeå University

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

New discoveries about Jupiter's magnetosphere

New discoveries about Jupiter could lead to a better understanding of Earth's own space environment and influence a long-running scientific debate about the solar system's largest planet.

"By exploring a larger space such as Jupiter, we can better understand the fundamental physics governing Earth's magnetosphere and thereby improve our space weather forecasting," said Peter Delamere, a professor at the UAF Geophysical Institute and the UAF College of Natural Science and Mathematics.

"We are one big space weather event from losing communication satellites, our power grid assets, or both," he said.

Space weather refers to disturbances in the Earth's magnetosphere caused by interactions between the solar wind and the Earth's magnetic field. These are generally associated with solar storms and the sun's coronal mass ejections, which can lead to magnetic fluctuations and disruptions in power grids, pipelines and communication systems.

Delamere and a team of co-authors detailed their findings about Jupiter's magnetosphere in a recent paper in AGU Advances . Geophysical Institute research associate professor Peter Damiano, UAF graduate student researchers Austin Smith and Chynna Spitler, and former student Blake Mino are among the co-authors.

Delamere's research shows that our solar system's largest planet has a magnetosphere consisting of largely closed magnetic field lines at its polar regions but including a crescent-shaped area of open field lines. The magnetosphere is the shield that some planets have that deflects much of the solar wind.

The debate over open versus closed at the poles has raged for more than 40 years.

An open magnetosphere refers to a planet having some open-ended magnetic field lines near its poles. These are previously closed lines that have been broken apart by the solar wind and left to extend into space without re-entering the planet.

This creates regions on Jupiter where the solar wind, which carries some of the sun's magnetic field lines, directly interacts with the planet's ionosphere and atmosphere.

Solar particles moving toward a planet on open field lines do not cause the aurora, which largely occurs on closed field lines. However, the energy and momentum of solar wind particles on open field lines does transfer to the closed system.

Earth has a largely open magnetosphere at its poles, with aurora occurring on closed field lines.. It is the transferred energy on those open lines that can disrupt power grids and communications.

In order to study Jupiter's magnetosphere, Delamere ran a variety of models using data acquired by the NASA Juno spacecraft, which entered Jupiter's orbit in 2016 and has an elliptical polar orbit.

"We never had data from the polar regions, so Juno has been transformative in terms of the planet's auroral physics and helping further the discussion about its magnetic field lines," Delamere said.

The debate began with the 1979 flybys of Jupiter by NASA's Voyager 1 and Voyager 2. That data led many to believe that the planet had a generally open magnetosphere at its poles.Other scientists argued that Jupiter's auroral activity, which is much different from Earth's, indicated the planet had a mostly closed magnetosphere at the poles. Delamere, a longtime researcher of Jupiter's magnetic field, published a paper supporting that view in 2010.

In 2021, he was a co-author on a paper by Binzheng Zhang of the University of Hong Kong that suggested through modeling that Jupiter's magnetosphere had two regions of open magnetic field lines at its poles. The model shows one set of open-ended field lines emerging from the poles and trailing outward behind the planet in the magnetotail, the narrow teardrop-shaped portion of the magnetosphere pointing away from the sun. The other set emerges from Jupiter's poles and goes off to the sides into space, carried by the solar wind.

"The Zhang result provided a plausible explanation for the open field line regions," Delamere said. "And this year we provided the compelling evidence in the Juno data to support the model result.

"It is a major validation of the Zhang paper," he said.

Delamere said it's important to study Jupiter to better understand Earth.

"In the big picture, Jupiter and Earth represent opposite ends of the spectrum -- open versus closed field lines," he said. "To fully understand magnetospheric physics, we need to understand both limits."

Delamere's evidence came via an instrument on the Juno spacecraft that revealed a polar area where ions flowed in a direction opposite Jupiter's rotation.

Subsequent modeling showed a similar ion flow in the same area -- and near the open field lines proposed in the 2021 paper by Zhang and Delamere.

"The ionized gas on [closed] magnetic field lines connected to Jupiter's northern and southern hemispheres rotates with the planet," Delamere's new paper concludes, "while ionized gas on [open] field lines that connect to the solar wind move with the solar wind."

Delamere writes that the polar location of open magnetic field lines "may represent a characteristic feature of rotating giant magnetospheres for future exploration."

Other contributors are from the University of Colorado Boulder, Johns Hopkins University, Andrews University, Embry-Riddle Aeronautical University, University of Hong Kong, University of Texas San Antonio, Southwest Research Institute and O.J. Brambles Consulting in the United Kingdom.

Delamere will present the research in July at the Conference on Magnetospheres of the Outer Planets at the University of Minnesota.

• Solar Flare
• Solar System
• Northern Lights
• Space Exploration
• Extrasolar Planets
• Titan (moon)
• Definition of planet
• Eris (dwarf planet)
• History of Earth

Story Source:

Materials provided by University of Alaska Fairbanks . Original written by Rod Boyce. Note: Content may be edited for style and length.

Journal Reference :

• P. A. Delamere, R. J. Wilson, S. Wing, A. R. Smith, B. Mino, C. Spitler, P. Damiano, K. Sorathia, A. Sciola, J. Caggiano, J. R. Johnson, X. Ma, F. Bagenal, B. Zhang, F. Allegrini, R. Ebert, G. Clark, O. Brambles. Signatures of Open Magnetic Flux in Jupiter's Dawnside Magnetotail . AGU Advances , 2024; 5 (2) DOI: 10.1029/2023AV001111

Cite This Page :

Explore More

• Fastest Rate of CO2 Rise Over Last 50,000 Years
• Like Dad and Like Mum...all in One Plant
• What Makes a Memory? Did Your Brain Work Hard?
• Plant Virus Treatment for Metastatic Cancers
• Controlling Shape-Shifting Soft Robots
• Brain Flexibility for a Complex World
• ONe Nova to Rule Them All
• AI Systems Are Skilled at Manipulating Humans
• Planet Glows With Molten Lava
• A Fragment of Human Brain, Mapped

Trending Topics

Strange & offbeat.

Skip to content

Search form

Dipping a toe in jupiter’s atmospheric ‘oceans’ and polar cyclones.

New NASA satellite images of polar cyclones on Jupiter are helping Annalisa Bracco and a network of fellow scientists understand the forces and fluid dynamics that drive these unique weather patterns.

Press release led by Scripps Institution of Oceanography .

Hurtling around Jupiter and its 79 moons is the  Juno spacecraft , a  NASA -funded satellite that sends images from the largest planet in our solar system back to researchers on Earth. These photographs have given oceanographers — including a professor with the  School of Earth and Atmospheric Sciences  — the raw materials for  a new study published today  in  Nature Physics  that describes the rich turbulence at Jupiter’s poles and the physical forces that drive the large cyclones. 

“It's really the first modern mission to understand the origin and evolution of Jupiter,” says  Annalisa Bracco , who studies ocean and climate dynamics and is one of 11 scientists who contributed to the study. “Jupiter’s poles were never observed before with this clarity. We had no idea that there were cyclones organized in structures, with a central one and five or seven around it. I think so far some key discoveries are related to the structure of Jupiter’s atmosphere.”

The study’s lead author,  Lia Siegelman , a physical oceanographer and postdoctoral scholar at  Scripps Institution of Oceanography  at the  University of California San Diego , decided to pursue the research after noticing that the cyclones at Jupiter’s pole seem to share similarities with ocean vortices she studied during her time as a Ph.D. student. Using an array of these images and principles used in geophysical fluid dynamics, Siegelman, Bracco, and their colleagues provided evidence for a longtime hypothesis that moist convection — when hotter, less dense air rises — drives these cyclones.

“When I saw the richness of the turbulence around the Jovian cyclones with all the filaments and smaller eddies, it reminded me of the turbulence you see in the ocean around eddies,” Siegelman says. “These are especially evident on high-resolution satellite images of plankton blooms, for example.” 

In addition to Siegelman and Bracco, the study’s collaborators include scientists from the  University of California San Diego , the  California Institute of Technology , and Italy’s main space sciences research organization,  Istituto Nazionale di AstroFisica — Istituto di Astrofisica e Planetologia Spaziali . 

See Jupiter hide behind the moon during a lunar occultation early on May 17

Early in the morning on Wednesday, May 17, gas giant Jupiter and its four bright Galilean moons will pass behind a very thin crescent moon.

The moon and Jupiter will be quite a sight in the early morning skies tomorrow.

Sometime before or after sunrise (depending on where you are) on Wednesday, May 17, gas giant Jupiter and its four bright Galilean moons will pass behind a very thin — only 5% illuminated — waning crescent moon as seen from North America. This occultation can best be watched from the western third of the United States and Canada, where at least part of it happens before sunrise. At locations where it occurs in a relatively dark sky, you might be able to watch Jupiter disappear using no optical aid at all — although binoculars will give a better view, and you will need a telescope to follow its moons. 

Jupiter will be covered first by the crescent moon's leading sunlit limb, with the moon requiring a minute or more to inch its way across the giant planet's face. Jupiter will reappear from behind the moon's dark edge about an hour or more later; again, the process will be gradual.

Related: Night sky, May 2023: What you can see tonight [maps]

West is best!

Want to get a good look at Jupiter and its four bright moons in the night sky? We recommend the  Celestron Astro Fi 102 as the top pick in our  best beginner's telescope guide . 

The best views of Jupiter's disappearance behind the moon will be from Washington state, Oregon, much of Idaho, Nevada, Utah, Arizona, New Mexico, northern and eastern California and the western half of Texas. For these places, Jupiter and the moon will be positioned low to the eastern horizon against a brightening twilight sky. 

Unfortunately, for western and southern sections of California, Jupiter will slip behind the moon prior to moonrise; when the moon first appears above the horizon (for places like San Francisco, Los Angeles and San Diego), Jupiter will already be behind the moon.

As for the reappearance, the western halves of Oregon, Nevada and Arizona as well as all of California are most favored, near and along the Pacific coast of the Golden State, the sun will be about eight degrees below the horizon, while the moon will be a similar distance above the horizon. The emergence of Jupiter from behind the moon's dark limb near mid-twilight could be quite spectacular.

Get the Space.com Newsletter

Breaking space news, the latest updates on rocket launches, skywatching events and more!

So far as the Galilean satellites are concerned, they can be glimpsed wherever the sun is at least five degrees below the horizon; the sky should still be sufficiently dark enough to see them with a telescope. Europa will not be visible as it will be immersed in Jupiter's shadow, but Io will be situated very near to Jupiter's eastern limb. Well to the west of Jupiter will be Callisto and Ganymede . In fact, as seen from California, Jupiter's emergence is proceeded by these two satellites by 11 and 7 minutes respectively. Instead of popping out instantaneously like a star, these satellites will "ooze" into view because their disks have an appreciable angular size. 

Problematic visibility farther east

Where Jupiter is occulted in broad daylight — and that will be the case anywhere east of a line running roughly from central Montana down to central Louisiana — it will take place against a bright blue sky (assuming the weather cooperates!). But your telescope still may show this interesting event. 

Probably the easiest option is to locate the moon and Jupiter before sunrise and track them into the day. About 30 to 40 minutes prior to sunup, look very near to the horizon, slightly north of due east. That's where you will find the slender lunar sliver with Jupiter sitting a degree or less to its left. 

The occultation happens during the early morning, with the moon and Jupiter generally being somewhat higher than the sun and well off to its right. If you're search after sunrise, the challenge will be finding the moon and Jupiter at all. Give yourself plenty of time in advance to do this. A lot will depend on the transparency of the sky — in other words, the deepness of its blue color. Point your scope about 28 degrees (nearly three fists-widths at arm's length) from the sun , mostly to the right and, for most locations, about 15 degrees higher. 

If you have a "Go-To" telescope mount or a telescope equipped with setting circles, you can be more accurate about it. But remember that the crescent moon will have a low surface brightness that will probably make it hardly distinguishable from the sky itself. Sweep around this region of the sky, then once you've got the moon, the next challenge is Jupiter. Not only will it appear much smaller (a sixtieth of the moon's diameter), but worse, it will have an even lower surface brightness. However, the moon will show you just where to look. 

Here's the schedule

We thank the International Occultation Timers Association (IOTA) for viewing data, which was taken from this site, which provides times for 953 different locations within the occultation viewing zone. All times on the site are listed in Universal Time (UT). IOTA also provides information regarding the altitudes of the sun and moon as well as a map depicting the region of visibility. While the moon occults Jupiter in the morning for the U.S., Canada, and Central America, the event will also take place during local afternoon hours as seen from northern Europe. 

In the timetable below, we list the local disappearance and reappearance times for 17 selected cities in the U.S., Canada and Mexico. If the time is listed has an asterisk (*), it indicates that the event takes place with the sun below the local horizon. Dashes for disappearance info concerning Los Angeles indicates that the moon is below the horizon for this event. 

If you are hoping to take a close look at the moon or Jupiter during lunar occultations such as the one happening on May 17, our guides to the  best telescopes  are a great place to start. If you want to see the two celestial bodies together during events like this one, turn instead to Space.com's guide to the  best binoculars , which offer a wider view of constellations, occultations or the entire moon.

And if you're looking to take your own photos of lunar occultations or the night sky in general, check out our guide on  how to photograph the moon , as well as our  best cameras for astrophotography  and  best lenses for astrophotography .

Editor's Note:  If you snap an image of the lunar occultation of Jupiter and would like to share it with Space.com’s readers, send your photo(s), comments, and your name and location to [email protected].  

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Joe Rao is Space.com's skywatching columnist, as well as a veteran meteorologist and eclipse chaser who also serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Joe is an 8-time Emmy-nominated meteorologist who served the Putnam Valley region of New York for over 21 years. You can find him on Twitter and YouTube tracking lunar and solar eclipses, meteor showers and more. To find out Joe's latest project, visit him on Twitter.

Ruko Veeniix V11 drone review

Solar eclipse 2024: Live updates

SpaceX launches 23 Starlink satellites from Florida

• rod The occultation event not visible at my location this morning but the waning crescent Moon and Jupiter quite lovely in binocular views. Observed 0500-0530 EDT. I was able to enjoy some of this celestial event using 10x50 binoculars. Some rain passed during the night and early morning sky featured altocumulus and cirrus clouds passing. The thin waning crescent Moon and Jupiter a lovely pair in my binocular view, almost another world view seeing the two about 1-degree 15 arcminutes apart according to Stellarium 23.1 for my location in MD. While not the best observing conditions, a good sight to see this morning. Temperature 15C, winds NW 8 knots. Sunrise near 0553 EDT. New Moon 19-May-2023 1553 UT. Reply
• View All 1 Comment

Most Popular

• 2 Scientists could make blazing-fast 6G using curving light rays
• 3 'Extreme' solar storms cook up sweet Mother's Day auroras for Moms everywhere
• 4 The stormy sun erupts with its biggest solar flare yet from a massive sunspot — and it's still crackling (video)
• 5 Houston, we have an encore: ISS virtual reality experience 'The Infinite' returns

What are you looking for?

Most popular topics.

• Sustainable Aviation Fuel (SAF)

13 May 2024

Juice: throwback to an out of this world rescue.

As we commemorate a year since the launch of the Jupiter Icy Moons Explorer (JUICE), we revisit a pivotal moment in space exploration history when the mission encountered a formidable challenge just days after lift-off with the RIME antenna on ESA’s JUICE failing to deploy. Through perseverance, ingenuity, and collaborative spirit, discover how the engineering teams from Airbus, ESA, and SpaceTech overcame adversity to unlock the secrets of Jupiter´s mysterious icy moons. 

Solving the RIME deployment mystery, success through collective intelligence

In April 2023, JUICE began an approximately  8 year cruise to Jupiter  to spend four years around the planet.

The RIME antenna with its radar is a key instrument for the JUICE mission. Its radar signals will penetrate Jupiter's moons to a depth of 9 km, and reveal details of between 50 and 140 m across. This will provide unique data to understand the habitability of these icy moons.

At 16 m in length, the RIME antenna was too long to fit inside the nose cone of the Ariane 5 rocket. It was therefore constructed in two booms of four deployed segments each. For the launch, three deployable segments on each side were folded back and held in place by two brackets.

Once in space, devices called non-explosive actuators (NEAs) were remotely activated from the European Space Operations Centre (ESOC), Darmstadt, Germany. Each NEA was set to remove a holding pin from its bracket, allowing that section to spring into place.

And that’s where the problems began.

17 April 2023, three days after the launch: deployment begins

The first step went without a hitch: the camera and on board accelerometers witnessed the first segment deployment. The command was given to fire the second actuator. It took a few seconds to download the camera image which showed that the boom segment was still clearly visible in its stowed configuration. The deployment had failed.

“We knew that we had to quickly try to understand what had happened, and then try to find a workaround,” says Frédéric Faye, Airbus’s chief engineer for Juice.

The next morning, with the disbelief banished from their minds, the teams set to solving the mystery. They knew they had to find some way to free the stuck segment, but without compromising the deployment of the other segments, or indeed the rest of the spacecraft.

A first idea: “effect of the cold” or even “ice on the pin”

At the time of firing the second actuator, the bracket was at -80°C, so the first thoughts were that perhaps a thermoelastic effect had led to some shrinkage, or maybe some ice had formed on the pin holding the segment in place. Since there are no heaters on the spacecraft near the support brackets of the RIME antenna, removing the ice would mean rotating the spacecraft so that the antenna faced the Sun. But, the surface of the spacecraft holding the RIME antenna was designed to be a ‘cold face’.

After several days of study, the team began gradually slewing the spacecraft so that the surface was illuminated. Unfortunately, the slew and associated warming up did not succeed in releasing the antenna, thus eliminating the ice formation as the root cause.

A second scenario: a stuck pin

The second hypothesis was that the pin had simply stuck due to a mechanical effect more than a temperature effect. Then perhaps shaking the spacecraft would jog it loose. The stuck pin probably only needed moving by a millimetre or two, but they could not risk harming anything else with a violent jolt of the spacecraft. So, they began testing this manoeuvre cautiously : defining a train of thruster pulse specifically timed to excite the RIME antenna and nothing else. After several thruster firings the teams only saw small movements within the bracket.

A new recovery plan: closeby shock

The manufacturer of the antenna, SpaceTech, managed to reproduce the anomaly with a model of the antenna that had been used for testing and confirmed that the firing of the closest NEA usually managed to dislodge the stuck pin. It was also identified that to increase the chances of a successful outcome, the antenna should be heated by exposure to sunlight.

“We did eight slews over two weeks to illuminate the RIME bracket,” says Angela Dietz, ESA Spacecraft Operations Manager at ESOC. Each time they exposed the surface for longer, to understand the limits of this operation. By the end they felt comfortable exposing the surface for 73 minutes at a time.

It was now several weeks since the anomaly had occurred and the pressure was building up. The mission had a timetable to keep. “To me this was the most complicated thing during the recovery,” says Guillaume Chambon, in charge of managing the Airbus side of the recovery. “You have to be fast enough to act because everyone is expecting you to make progress, but you need to take enough time to consider all the side effects of what you are proposing,” he says.

Think twice before taking action

One afternoon, while contemplating the rescue attempt, Guillaume did indeed realise a potential problem. If they went ahead with the nominal deployment sequence, there was a chance that two segments of the antenna could collide.

So, the teams agreed to reorder the deployment sequence, and the recovery attempts began. First, the spacecraft was heated to drive off any ice, but the antenna remained fixed. And so it became obvious that the only possibility to recover the antenna was to heat the antenna again, and then continue with the deployment in the hope that the shocks from the other NEAs would unjam the pin.

It was all or nothing

Following the longest spacecraft slew, the bracket had been in sunlight for its maximum permitted time that day of 73 minutes, the spacecraft was rotated back, moving the antenna away from the Sun to avoid large thermal gradients and the teams began their final attempt. The command was sent and the first telemetry was positive, but they had to wait long minutes for the visual confirmation: Total success: the first three segments of the antenna were finally deployed!

But the job was not over yet. One other NEA still needed to be fired to deploy the second boom. It was at this point that Cyril Cavel, the JUICE project manager for Airbus found himself thinking about the scientists who were depending on them. Some had even been working on the antenna for decades. “ The RIME antenna was an industrial delivery to these people. Without this antenna, the radar experiment would be either very reduced or even worthless ,” he says.

For the best chance of success on release of the next bracket there was a further wait. “Those three to four hours were very long,” says Frédéric. 

When the conditions were right, the command was sent and finally, the cameras confirmed the teams’ victory. RIME was now in its fully deployed configuration.

A success made possible thanks to the commitment and ingenuity of the RIME anomaly teams at ESA, Airbus and SpaceTech. The JUICE mission is now one-year into its 8-year journey to Jupiter, ready for science and exploration of new frontiers. 

Latest News

Airbus expands its Earth observation constellation with Pléiades Neo Next

EarthCARE satellite set to explore the Earth’s skies