Jupiter, the largest planet in the Solar System, contains nearly 3/4 of all planetary matter.
Although observed and studied from Earth for centuries, it was not until the mid-1970s that humans were able to get a closer look with the spacecraft Pioneer 10 and 11. The Voyager 1 and 2 spacecraft were launched with the specific purpose of collecting information and data. In December 1995, the Galileo spacecraft entered into orbit and began its long-term study of Jupiter and its moons; a probe was also sent deep into the atmosphere of the gas giant.
With no solid surface, Jupiter is a gas and liquid filled giant. Its turbulent belts of clouds circulate parallel to the equator and often contain oval spots which are storm systems with the largest being easily twice the diameter of Earth. The great red spot has been observed for at least 300 years and rotates counter-clockwise with wind speeds of 430 km/hr.
- Diameter: 142,900 km (11.2 x Earth's diameter)
- Average Density: 1.34g/cm3
- Mass: 1.899 x 1027 kg (317.83 x Earth's Mass)