Background
Jupiter is the fifth-closest planet to the sun and the largest and oldest planet in the solar system.
Named after the king of Roman gods, this gas giant is most easily recognized by its Great Red Spot—a hurricane-like storm larger than Earth that has existed for about 200 years.
With more than twice the mass of all other planets combined, thousands of objects—including over 90 moons—orbit Jupiter, and its gravity has played a key role in the solar system’s evolution.
Formation
As with all planets in our solar system, Jupiter formed from what remained of the cloud of gas that collapsed into the sun and protoplanetary disk (see examples).
The disk contained heavy elements, dust grains, and pebbles that collided gravitationally, forming larger pieces of matter—called planetesimals—that would become the building blocks for planets.
These planetesimals likely collided to form Jupiter within a few million years, fast enough to accumulate gas from the disk before solar winds blew it away (watch explainer).
However, models differ on where Jupiter formed to have attained its observed composition. Some simulations suggest it migrated inward from near Uranus’ orbit or migrated inward from the asteroid belt before migrating back out again (watch explainer).
Atmosphere
Convection, the transfer of heat through the movement of fluids, and rapid rotation produce Jupiter’s latitudinal banding, its horizontal streaks, and turbulent features (see gallery).
For billions of years, Jupiter has been shrinking and generating more heat than it receives from the sun by converting gravitational potential energy. Its core—almost five times hotter than the sun’s surface—heats fluids into rising, while cooler fluids sink.
Changes in temperature and composition result in different chemical reactions that produce various colors—rising gases tend to be white, and sinking ones tend to be orange.
Observations of Jupiter reveal differential rotation—different latitudes rotate at different rates. Averaged across all locations, a day on Jupiter is 9.9 hours long, making it the fastest rotating planet in the solar system.
Jupiter’s rapid rotation smears the rising and sinking material across the planet into bright zones and dark belts, respectively. These form the characteristic east-west zonal flows that wrap around the planet like global jet streams. The opposing flows at the boundaries between belts and zones create eddies—turbulent swirls of fluid—including the Great Red Spot (learn more).
Jupiter has three unique cloud layers: a top layer of colorless ammonia ice, a middle layer of ammonia hydrosulfide ice crystals, and a lower layer of water ice and vapor. Clouds of sulfur- and phosphorus-containing gases produce the reds, browns, and yellows seen in belts.
Interior
Like the sun, Jupiter is mainly made of hydrogen in different states of matter.
Modeling its interior using observational data suggests that the hydrogen gas gradually liquefies with depth until about 20,000 km (12,427 miles), where the immense pressure pushes electrons out of hydrogen atoms, turning them into a highly conductive liquid metal.
Metallic hydrogen is thought to produce Jupiter’s magnetosphere, which is larger than the sun and capable of producing auroras (see them here).
Jupiter’s core is poorly understood. Observations from the Juno spacecraft suggest it is not distinct from the surrounding metallic hydrogen but “fuzzy,” partly composed of rocky material, and extending to nearly half the planet’s diameter.
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