Jupiter
Planet
Facts
- Diameter
- 142,984 km
- Mass
- about 318 times Earth
- Mean distance from the Sun
- 778.5 million km
- Orbital period
- 11.9 years
- Rotation
- 9.9 hours
- Mean temperature
- −110 °C
Jupiter is the largest planet in the Solar System, made mostly of hydrogen and helium like the Sun, and it is named after the king of the gods in Roman mythology. It has about two and a half times the mass of all the other planets put together.
The Great Red Spot is a swirl of clouds twice as wide as Earth, watched for more than 300 years. The magnetic field is 16 to 54 times stronger than Earth's, and the magnetosphere reaches 1 to 3 million km towards the Sun, with a tail almost a billion km long.
In 1610 Galileo Galilei was the first to see its four largest moons: Io, Europa, Ganymede and Callisto. In 1979 Voyager 1 discovered its rings, which are hard to see unless lit from behind. NASA's Juno probe, by measuring gravity and the magnetic field, found that the core may be much larger than expected and not solid; Europa Clipper, launched on 14 October 2024, is on its way to the moon Europa.