Jupiter is by far the biggest planet of the solar system. Its orbit is at a distance of approximately 500 million miles from the sun. The mass of Jupiter is greater than 300 times the earth?s mass. The diameter of Jupiter is 142,600 km and the gravity is 2.34 times of the earth. Jupiter?s atmosphere consists of 90% hydrogen, 10% helium and traces of ammonia and methane. Jupiter is only next to the sun in emitting heat in the solar system. Like Saturn, Jupiter has a ring though it is relatively thinner. Its ring is 1km thick and around 5920 km wide. Jupiter has a powerful wind system. It is believed to have a small rocky center. Jupiter has over 63 moons. out which the prominent ones are Sinope, Ganymede, Metis, Thebe, and Europa.
Moons of Jupiter
Galileo, the famous Italian astronomer, discovered four moons of Jupiter in the year 1610. They were Europa, Callisto, Io and Ganymede and also dubbed the “Galilean Moons”.
Ganymede
The astronomer Simon Marius suggested the name “Ganymede”. In Greek mythology, Ganymede was a cup bearer of the Greek gods. This is the largest moon of Jupiter and also the largest moon of the solar system. The mass of Ganymede is half of that of Mercury and has a diameter of 5,262 Km. The density of the moon is quite low at 1.94 gm/cm3. Ganymede?s crust is believed to be a thick layer of water ice. Ganymede is bigger than the planets Mars and Mercury. The moon has no known atmosphere although recently ozone was detected at its surface.
Europa
According to Greek mythology, Europa is a name of Phoenician princess who the Greek god Zeus fell in love with. It is distinguished by the red cracks which criss-cross its surface. Europa is the fourth largest of Jupiter?s moons. The diameter of this moon of Jupiter is 3,138 km. Europa?s orbit is at a distance of 670,900 km from Jupiter and the mass is 4.80×1022 kg. Europa is believed to have water and thus the potential of harboring life.
Io
In Greek mythology, Io was the name of the woman who Jupiter was enamored with. Io is the third largest moon of Jupiter and has many active volcanoes which release sulphuric acid. Its diameter is 3,363 km and it orbits at a distance of 422,000 km from Jupiter. The orbital time period is 1.77 days and it possess a mass of 8.93×1022 kg.
Callisto
Callisto is a nymph who the greek god Zeus fell in love with but was hated by the Greek goddess Hera. This moon of Jupiter is the second largest one and nearly the same size as that of mercury. The crust of the moon Callisto is around four billion years old. The diameter of Callisto is 4,800 km and it orbits at a distance of 1,883,000 km from Jupiter. It has the most cratered surface of all the heavenly bodies in the solar system and its mass is1.08x1023kg.
There are possibilities of discovering more moons of Jupiter. Eleven new moons were discovered in 2002 and eight in 2003. The scientific quest to discover more moons of Jupiter is being carried out in earnest.