Jupiter

Jupiter is the largest planet in the Solar System and one of the most extraordinary worlds orbiting the Sun. This immense gas giant contains more than twice the mass of all the other planets combined.

With its colorful cloud bands, giant storms, powerful magnetic field, and large family of moons, Jupiter is one of the most impressive sights visible through a telescope.

A Giant Made of Gas

Jupiter is composed mostly of hydrogen and helium, similar to the Sun. It does not have a solid surface that a spacecraft could land on. Instead, its atmosphere becomes denser and hotter with depth.

Deep inside Jupiter, extreme pressure changes hydrogen into an electrically conducting fluid often called metallic hydrogen. Scientists think Jupiter may have a diffuse core region containing heavier elements, but its exact structure is still being studied.

Atmosphere and Giant Storms

Jupiter's atmosphere features alternating light and dark cloud bands, powerful winds, lightning storms, and brilliant polar auroras. Its most famous feature is the Great Red Spot, a vast storm that has been observed for centuries and is still larger than Earth.

The Great Red Spot has changed in size and color over time, showing that Jupiter's atmosphere is constantly active. Smaller storms and swirling clouds also cover much of the planet.

Key Facts About Jupiter

Diameter: About 88,846 miles (139,820 kilometers)
Mass: About 318 times Earth's mass
Average Distance from the Sun: About 484 million miles (5.2 AU)
Day Length: About 9.9 hours
Year Length: About 11.9 Earth years

The Galilean Moons

Jupiter has 101 known moons, including the four large Galilean moons discovered by Galileo Galilei in 1610: Io, Europa, Ganymede, and Callisto.

Io: The most volcanically active body in the Solar System.
Europa: An icy moon with a global ocean beneath its crust and a major target in the search for potentially habitable environments.
Ganymede: The largest moon in the Solar System and the only known moon with its own magnetic field.
Callisto: An ancient, heavily cratered moon that may also contain an ocean deep beneath its surface.

A Powerful Magnetic Field

Jupiter has the strongest planetary magnetic field in the Solar System. It creates intense radiation belts and a vast region of charged particles called the magnetosphere.

Jupiter's powerful gravity strongly influences the paths of comets and asteroids throughout the Solar System. It can redirect or capture some objects, although its overall effect on impact risks for the inner planets is complex.

Exploration of Jupiter

Spacecraft including Pioneer, Voyager, Galileo, and Juno have studied Jupiter and its moons. Juno, which entered orbit around Jupiter in 2016, has provided detailed information about the planet's atmosphere, interior, magnetic field, and polar storms.

NASA's Europa Clipper spacecraft launched in 2024 and is expected to reach the Jupiter system in 2030. It will make repeated close flybys of Europa to investigate its ocean and determine whether conditions beneath the ice could support life.

The King of the Planets

Jupiter's immense size, violent storms, powerful gravity, and fascinating moons make it one of the most important worlds in the Solar System. Studying it helps scientists understand how giant planets form, how planetary systems evolve, and what conditions may exist around planets orbiting other stars.