Hydrogen and helium are the gases found in the atmosphere of Jupiter. The atmosphere of Jupiter comprises 90% of hydrogen and 10% of helium. However, the atmosphere of Jupiter also comprises compounds such as methane, water vapour, ammonia and sulphur. The gases form a tiny percentage of Jupiter’s atmosphere with major gases being helium and hydrogen.

Jupiter is the largest planet of the solar system. Jupiter comprises a dense core with a mixture of elements. The inner layer consists of liquid metallic hydrogen with a little bit of helium whereas the outer layer consists of molecular hydrogen. Jupiter is at a distance of 778.5 million km from the Sun. The radius of the planet is 69911 km. With respect to Sun, Jupiter is the fifth planet of the solar system. The mass of Jupiter is one-thousandth to that of the Sun. Combining the mass of all other planets of the solar system the mass of Jupiter is two and a half times. The mass of Jupiter is 1.8982 * 10^27 kg (4.1848 * 10^27 lb) and 317.8 times of the mass of Earth and 1/1047 times of the mass of Sun. The surface area of Jupiter is 6.1419 * 10^10 sq km (2.3714 * 10^10 sq mi) and 121.9 times to the surface area of Earth. The volume of Jupiter is 1.4313 * 10^15 cu km (3.434 * 10^14 cu mi) and 1321 times the volume of the Earth. The mean density of Jupiter is 1326 kg/cu m (2235 lb/cu yd).

Jupiter has around 69 moons. Some of the moons of the planet are Europa, Ganymede, Callisto etc. The moons were discovered by Galileo Galilei (15th February 1564 – 8th January 1642) in 1610. The moons are also known as Galilean moons. Ganymede is the largest of these moons and has a diameter greater than the planet Mercury.