Jupiter is the largest planet in the solar system and is big enough to contain more than a thousand Earths. Four of its many moons were among the first ever astronomical discoveries made with a telescope, by Galileo in 1610. More were identified be later astronomers and in 1979 by the space probe Voyager 2. The NASA Juno mission to jupiter is planned for launch in 2011. Diameter: 142,984 km Mass: 18,986,000,000,000,000 tonnes Average distance from Sun: 778,412,010 km Rotation: 9 hours 50 minutes Orbit: 11 years 314 days Average temperature: -150 ◦ C Moons: 63