Jupiter
The largest planet, a gas giant with a mysterious core
The Fifth Planet from the Sun
Overview
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined.
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements.
The planet's vivid colors are the result of cloud layers at different depths in its atmosphere. The famous Great Red Spot is a giant storm that has been observed since the 17th century and is larger than Earth.
Atmosphere & Features
Jupiter's atmosphere is about 90% hydrogen and 10% helium by volume. Since helium atoms are more massive than hydrogen molecules, Jupiter's atmosphere is approximately 75% hydrogen and 24% helium by mass.
Mass
More massive than Earth
Diameter
11x Earth's diameter
Moons
Confirmed natural satellites
The Great Red Spot is Jupiter's most distinctive feature - a persistent high-pressure region in the atmosphere that produces an anticyclonic storm, the largest in the Solar System. It has been continuously observed since 1830 and may have existed for more than 350 years.
The Galilean Moons
Jupiter has 95 known moons, but the four largest - Io, Europa, Ganymede, and Callisto - were discovered by Galileo Galilei in 1610 and are known as the Galilean moons. They are among the most fascinating worlds in our solar system.
Io
The most volcanically active body in the solar system, with over 400 active volcanoes.
Europa
Has a smooth, icy surface covering a global ocean that may harbor life.
Ganymede
The largest moon in the solar system, larger than the planet Mercury.
Callisto
Heavily cratered surface, possibly the most ancient landscape in the solar system.
Jupiter Exploration
Jupiter has been explored by several spacecraft, beginning with Pioneer 10 in 1973. The most significant missions include Voyager 1 and 2, Galileo, and Juno.
Juno Mission
NASA's Juno spacecraft arrived at Jupiter in 2016 and is currently studying the planet's composition, gravity field, magnetic field, and polar magnetosphere.
Juno's discoveries include finding that Jupiter's core is larger and more diffuse than expected, and that the planet's iconic bands extend deep into its atmosphere.
Astounding Facts About Jupiter
Planetary Protector
Jupiter's gravity helps protect Earth by deflecting or capturing dangerous comets and asteroids.
Powerful Magnetosphere
Jupiter's magnetic field is 20,000 times stronger than Earth's and is the largest structure in the solar system.
Faint Ring System
Jupiter has a faint ring system discovered in 1979 by the Voyager 1 spacecraft.
Failed Star
Jupiter is sometimes called a "failed star" because it has a similar composition to the Sun but lacks the mass to sustain nuclear fusion.
Jupiter's Scale
Jupiter's immense size is difficult to comprehend. To help visualize its scale:
Diameter: 142,984 km
Volume: 1,321 Earths could fit inside Jupiter
If Jupiter were hollow, more than 1,300 Earths could fit inside. Despite its size, Jupiter is the fastest-spinning planet, completing a rotation in just under 10 hours.
Future Exploration
Future missions to Jupiter will focus on its intriguing moons, particularly Europa, which has a global ocean beneath its icy crust that may harbor conditions suitable for life.
NASA's Europa Clipper mission, scheduled to launch in the 2020s, will conduct detailed reconnaissance of Europa's ice shell and subsurface ocean. The JUICE (JUpiter ICy moons Explorer) mission by ESA will study Ganymede, Callisto, and Europa.
These missions may help answer one of humanity's most profound questions: Are we alone in the universe?