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Jupiter: Facts about our solar system's largest planet

Hubble's view of Jupiter on Sept. 4, 2021, captured a more reddish equator than expected and bright red, elongated storms called "barges."
Hubble's view of Jupiter on Sept. 4, 2021, captured a more reddish equator than expected and bright red, elongated storms called "barges." (Image credit: NASA, ESA, A. Simon (NASA-GSFC), and M. H. Wong (UC Berkeley); Image Processing: J. DePasquale (STScI))

Jupiter is the largest planet in the solar system, named after the king of the gods in Roman mythology.

The gas giant Jupiter is a stormy enigma, wrapped in colorful clouds whipped by strong winds that sweep below circles of rings and moons. Jupiter is gigantic: The planet contains more than twice the mass of all the other solar system planets combined. Its biggest and most famous storm, the Great Red Spot, is twice the width of Earth.

Jupiter helped to revolutionize the way we saw the universe — and our place in it — in 1610, when Galileo discovered Jupiter's four large moons: Io, Europa, Ganymede and Callisto. These observations were the first time that celestial bodies were seen circling an object other than Earth, and supported the Copernican view that Earth was not the center of the universe.

Since 2016, the NASA spacecraft Juno has been investigating Jupiter and its moons.

How big is Jupiter?

Jupiter is more than twice as massive as all the other planets combined, according to NASA (opens in new tab). Jupiter's immense volume could hold more than 1,300 Earths. If Jupiter were the size of a basketball, Earth would be the size of a grape.

Jupiter was probably the first planet to form in the solar system, made up of gasses leftover from the formation of the sun. If the planet had been about 80 times more massive during its development, it would have actually become a star in its own right, according to NASA (opens in new tab)

How far is Jupiter from the sun?

On average, Jupiter orbits at about 483,682,810 miles (778,412,020 kilometers) from the sun. That's 5.203 times farther than Earth's average distance from the sun. 

At perihelion, when Jupiter is closest to the sun, the planet is 460,276,100 miles (740,742,600 km) away. 

At aphelion, or the farthest distance that Jupiter reaches from the sun, it is 507,089,500 miles (816,081,400 km) away. 

What is Jupiter like?

Diagram of Jupiter’s possible interior structure. Observations by NASA’s Jupiter-orbiting Juno spacecraft are already helping to flesh out this picture; Juno’s gravity data suggest, for example, that Jupiter may have a surprisingly large, partially dissolved core, mission team members have said.

Diagram of Jupiter’s possible interior structure. Observations by NASA’s Jupiter-orbiting Juno spacecraft are already helping to flesh out this picture; Juno’s gravity data suggest, for example, that Jupiter may have a surprisingly large, partially dissolved core, mission team members have said. (Image credit: NASA/JPL-Caltech/SwRI)

Jupiter's atmosphere resembles that of the sun, made up mostly of hydrogen and helium. A helium-rich layer of fluid metallic hydrogen envelops a “fuzzy” or partially-dissolved core at the center of the planet. 

The colorful light and dark bands that surround Jupiter are created by strong east-west winds in the planet's upper atmosphere traveling more than 335 mph (539 km/h). The white clouds in the light zones are made of crystals of frozen ammonia, while darker clouds made of other chemicals are found in the dark belts. At the deepest visible levels are blue clouds. Far from being static, the stripes of clouds change over time

Inside the atmosphere, diamond rain may fill the skies, and hidden deep within the atmosphere is a dense core of unknown composition.

Jupiter's gargantuan magnetic field is the strongest of all the planets in the solar system, at nearly 20,000 times the strength of Earth's, according to the University of Colorado at Boulder (opens in new tab). The magnetic field traps electrons and other electrically charged particles in an intense belt that regularly blasts the planet's moons and rings with radiation more than 1,000 times the level lethal to a human. The radiation is severe enough to damage even heavily shielded spacecraft, such as NASA's Galileo probe. The magnetosphere of Jupiter swells out some 600,000 to 2 million miles (1 million to 3 million km) toward the sun and tapers to a tail extending more than 600 million miles (1 billion km) behind the massive planet.

Jupiter broadcasts more radio waves than any object in the solar system besides the sun, according to the Smithsonian National Air and Space Museum (opens in new tab). This emission comes in two forms — one, the strong bursts that occur when Io, the closest of Jupiter's large moons, passes through certain regions of Jupiter's magnetic field, and the other continuous radiation from Jupiter's surface and high-energy particles in its radiation belts.

Jupiter also spins faster than any other planet, taking a little under 10 hours to complete a turn on its axis, compared with 24 hours for Earth. This rapid spin makes Jupiter bulge at the equator and flatten at the poles.

The interaction of Jupiter's gravitational field and that of the sun also influences a group of more than 11,000 (opens in new tab) intriguing asteroids clustered into the regions preceding and following Jupiter in its orbit around the sun. These asteroids are known as the Trojans and were named after characters in Homer's epic The Iliad, a classic work about the Trojan war. NASA launched Lucy, the first-ever mission to Jupiter's Trojan asteroids, in October 2021.

What is the Great Red Spot?

A flake of red peels away from Jupiter’s Great Red Spot during an encounter with a smaller anticyclone, as seen by the Juno spacecraft’s high resolution JunoCam on 12 February 2019. Although the collisions appear violent, planetary scientists believe they are mostly surface effects.

A flake of red peels away from Jupiter’s Great Red Spot during an encounter with a smaller anticyclone, as seen by the Juno spacecraft’s high resolution JunoCam on 12 February 2019. Although the collisions appear violent, planetary scientists believe they are mostly surface effects. (Image credit: AGU/Journal of Geophysical Research: Planets)

One of Jupiter's most famous features is the Great Red Spot, a giant hurricane-like storm that's lasted more than 300 years. According to NASA (opens in new tab), the Great Red Spot at its widest is about twice the size of Earth, and its edge spins counterclockwise around its center at speeds of about 270 to 425 mph (430 to 680 kph). That counterclockwise spin makes it a type of storm called an "anticyclone."

The color of the storm, which usually varies from brick red to slightly brown, may come from small amounts of sulfur and phosphorus in the ammonia crystals in Jupiter's clouds. The spot has been shrinking for quite some time, although the rate may be slowing in recent years. 

Jupiter has many other storms, too. According to 2022 data from Juno, Jupiter's gargantuan polar cyclones are driven by convection, or heat rising from lower altitudes to the higher atmosphere, similar to the way ocean vortexes work on Earth. 

Jupiter's moons

Jupiter has a mind-boggling 79 known moons, mostly named after the paramours and descendants (opens in new tab) of the Roman god of the same name. The four largest moons of Jupiter, called Io, Europa, Ganymede and Callisto, were discovered by Galileo Galilei and so are sometimes called the Galilean moons.

Ganymede is the largest moon in our solar system, and is larger than both Pluto and Mercury. It is also the only moon known to have its own magnetic field, whose eerie sound NASA's Juno mission captured in 2021. The moon has at least one ocean between layers of ice, although according to a 2014 study from the journal Planetary and Space Science, it may contain several layers of ice and water stacked on top of one another, along with atmospheric water vapor first spotted in 2021. Ganymede will be the main target of the European Jupiter Icy Moons Explorer (JUICE) spacecraft scheduled to launch in 2023 and arrive at Jupiter's system in 2030.

Io is the most volcanically active body in our solar system. As Io orbits Jupiter, the planet's immense gravity causes "tides" in Io's solid surface that rise 300 feet (100 meters) high and generate enough heat to spur on the volcanism. Those volcanoes release more than one ton of material every second into the space around the moon, helping to create strange radio waves from Jupiter. The sulfur its volcanoes spew gives Io a blotted yellow-orange appearance, leading some to compare it to a pepperoni pizza. 

From time to time, the small round black shadows cast by Jupiter's four Galilean moons become visible in amateur telescopes as they cross (or transit) the planet's disk. Here's two of those shadows on Jupiter at the same time, cast by Europa and Ganymede.  (Image credit: Starry Night software)

The frozen crust of Europa is made up mostly of water ice, and it may hide a liquid ocean that contains twice as much water as Earth's oceans do. Some of this liquid spouts from out of Europa's southern pole in sporadic plumes, and in 2021 the Hubble Space Telescope spotted more water vapor above Europa's surface. Also in 2021, Europa's north pole was photographed for the first time, and the discovery of underwater volcanoes raised hopes that Europa could be hospitable to life.

With the National Oceanic and Atmospheric Administration (NOAA) and the Woods Hole Oceanographic Institute, NASA may someday send an autonomous submersible to explore Europa's ice-covered oceans. Additionally, NASA's Europa Clipper mission, a planned spacecraft that would launch in the 2020s, would perform 40 to 45 flybys to examine the habitability of the icy moon.

Callisto has the lowest reflectivity, or albedo, of the four Galilean moons. This suggests that its surface may be composed of dark, colorless rock. Once considered a boring counterpart to the other Galilean moons, Callisto's heavily-cratered surface might conceal a secret ocean, according to NASA (opens in new tab).

Jupiter's rings

The star-tracker camera aboard NASA’s Juno spacecraft captured this view of Jupiter’s faint rings on Aug. 27, 2016, during the probe’s first data-gathering close approach to the giant planet. It’s the first-ever view of the rings from inside of them. The bright star above the main ring is Betelgeuse, and Orion’s belt can be seen in the lower right.

The star-tracker camera aboard NASA’s Juno spacecraft captured this view of Jupiter’s faint rings on Aug. 27, 2016, during the probe’s first data-gathering close approach to the giant planet. It’s the first-ever view of the planet's rings from inside of them. The bright star above the main ring is Betelgeuse, and Orion’s belt can be seen in the lower right. (Image credit: NASA/JPL-Caltech/SwRI)

Jupiter's three faint rings came as a surprise when NASA's Voyager 1 spacecraft discovered them around the planet's equator in 1979. Much more tenuous than Saturn's chunky, colorful rings, Jupiter's rings are made of continuous streams of dust particles emitted by some of the planet's moons, according to NASA's Goddard Space Flight Center (opens in new tab)

The main ring is flattened, according to the Southwest Research Institute's (SwRI's) Juno Mission (opens in new tab) website. It is about 20 miles (30 km) thick and more than 4,000 miles (6,400 km) wide.

The inner donut-shaped (also called “toroidal”) ring, called the halo, is more than 12,000 miles (20,000 km) thick, wrote SwRI. The halo is caused by electromagnetic forces that push grains away from the plane of the main ring. Both the main ring and halo are composed of small, dark particles of dust.

The third ring, known as the gossamer ring because of its transparency, is actually three rings of microscopic debris from three of Jupiter's moons: Amalthea, Thebe and Adrastea. According to a press release (opens in new tab) from NASA's Galileo mission, the gossamer ring is probably made up of dust particles about the same size of the particles found in cigarette smoke, and extends to an outer edge of about 80,000 miles (129,000 km) from the center of the planet and inward to about 18,600 miles (30,000 km).

Ripples in the rings of both Jupiter and Saturn may be signs of impacts from comets and asteroids.

Exploring Jupiter

NASA's Juno mission arrived at Jupiter in 2016 with an intended lifespan of about 20 months in orbit, but as of 2022 continues to return beautiful images, audio and other data, with its mission extended until 2025. 

Historically, seven missions have flown by Jupiter — Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysses, Cassini and New Horizons. Only two missions — NASA's Galileo and Juno — have orbited the planet. 

Pioneer 10 revealed how dangerous Jupiter's radiation belt is, while Pioneer 11 provided data on the Great Red Spot and close-up pictures of Jupiter's polar regions. Voyagers 1 and 2 helped astronomers create the first detailed maps of the Galilean satellites, discovered Jupiter's rings, revealed sulfur volcanoes on Io and detected lightning in Jupiter's clouds. Ulysses discovered that the solar wind has a much greater impact on Jupiter's magnetosphere than scientists previously thought. New Horizons took close-up pictures of Jupiter and its largest moons.

Jupiter's first orbiter, Galileo, arrived in 1995 and soon sent a probe plunging toward Jupiter, making the first direct measurements of the planet's atmosphere and measuring the amount of water and other chemicals there. Then the main spacecraft spent eight years studying the system. When Galileo itself ran low on fuel, the spacecraft was intentionally crashed into Jupiter to avoid any risk of it bringing contamination from Earth to Europa, which might have an ocean below its surface capable of supporting life.

A multitude of swirling clouds in Jupiter's dynamic North Temperate Belt is captured in this image from NASA's Juno spacecraft.

A multitude of swirling clouds in Jupiter's dynamic North Temperate Belt is captured in this image from NASA's Juno spacecraft. (Image credit: NASA)

Now, Juno studies Jupiter from a polar orbit, in part to figure out how it and the rest of the solar system formed. Researchers hope the mission could also shed light on how alien planetary systems might have developed. According to data from Juno, Jupiter's core may be larger than scientists expected, while Jupiter's stripes and storms stretch from high in the atmosphere to deep inside the planet. In a 2021 NASA overview (opens in new tab) of Juno's biggest hits, the agency also included observing lightning on Jupiter, detecting water in the atmosphere and measuring magnetic fields 10 times stronger than any found on Earth.

Although no missions dedicated to Jupiter itself are in the works, two future spacecraft will study Jupiter's moons: NASA's Europa Clipper (which would launch in the mid-2020s) and the European Space Agency's Jupiter Icy Moons Explorer (JUICE) that will launch in 2023 and arrive at Jupiter's system in 2030 to study Ganymede, Callisto and Europa.

How did Jupiter shape our solar system?

As the most massive body in the solar system after the sun, Jupiter has helped shape the fate of our neighborhood in space with its immense gravity. 

Jupiter's gravity has been found responsible for slinging Neptune and Uranus (along with a host of smaller objects like asteroids) away from the sun, according to a 2005 paper published in the journal Nature (opens in new tab). That paper established a theory of "planetary genealogy" called the Nice model, named after the French city where it was developed. 

According to the Nice model, Jupiter and other gas giants were also responsible for the Late Heavy Bombardment, a period of time when the young planet Earth and its nearby fellows were barraged with debris. 

Nowadays, Jupiter may help keep asteroids and comets from bombarding Earth, protecting the inner planets by acting as the "vacuum cleaner of the solar system," wrote SwRI (opens in new tab). Its enormous gravity can suck in and absorb smaller objects — as with the spectacular 1994 collision of Jupiter and Comet Shoemaker-Levy 9 — or propel them out of the solar system entirely. But that same gravity can still accelerate some of those objects toward the inner planets, too, so it's a mixed blessing.

Could there be life on Jupiter?

Jupiter's atmosphere grows warmer with depth, reaching room temperature, or 70 degrees Fahrenheit (21 degrees Celsius), at an altitude where the atmospheric pressure is about 10 times as great as it is on Earth. Scientists suspect that if Jupiter has any form of life, it would have to be airborne at this level. Theoretically, a 2021 study found, there is enough water to support some life. However, researchers have found no evidence of life on Jupiter.

Jupiter's moons are a different story: Europa in particular could host a radiation-shielded hidden ocean, and marine life might float somewhere in those alien waters.

Additional resources and reading

Read this 2018 interview from PBS NewsHour (opens in new tab) with JunoCam’s lead scientist Candice Hansen-Koharchek, who connects the camera aboard NASA's Juno mission to the public and lets anyone participate in the science around Jupiter. For more on Jupiter's possible pasts as a major mover-and-shaker in the solar system, read this overview article published in 2020 by the journal Proceedings of the National Academy of Sciences (opens in new tab) that discusses both the Nice model and newer theories of Jupiter's history. Writer Marina Koren discovers that Jupiter's Great Red Spot might actually be more of a pale rosy color in this piece from The Atlantic (opens in new tab) on the true colors of the solar system. And for an in-depth video look at the solar system's biggest planet, check out the Jupiter episode of NOVA (opens in new tab)'s "The Planets" series, narrated by actor Zachary Quinto. 

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Charles Q. Choi is a contributing writer for Space.com and Live Science. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica. Visit him at http://www.sciwriter.us

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