400 years ago, Galileo directed his rudimentary telescope to the planet Jupiter and saw that three dots that looked like moons accompanied him. I had just discovered that Jupiter has satellites.
During the following nights he continued watching and, four days later, discovered another. They could not be stars, because he had observed that they revolved around the planet. They were satellites and, until then, no other planet was known to have them (except ours, of course).
Then 12 more moons were discovered, all of them small, to complete a total of 16. Voyager ships studied and photographed the Jupiter system in 1979. Then, in 1996 a new project was launched that would allow Jupiter and its moons to observe a good season. This ambitious project, of course, was called Galileo.
The observations made by the probes that have approached Jupiter have made it possible to locate many other small Jupiter satellites. Up to a total of 67 had been discovered in 2011 and, since then, their number is still increasing. In 2018, 79 moons were discovered.
|Jupiter satellites||Radius (km)||Distance (km)|
Ganymede: It is the largest satellite of Jupiter and also of the Solar System, with 5,262 km in diameter, larger than Pluto and Mercury. It rotates about 1,070,000 km from the planet in just over seven days.
It seems to have a rocky core, a blanket of ice water and a crust of rock and ice, with mountains, valleys, craters and lava rivers.
Callisto: It has a diameter of 4,800 km., Almost the same as Mercury, and turns 1,883,000 km from Jupiter, every 17 days. It is the satellite with more craters in the Solar System.
It is formed, in equal parts, by rock and ice water. The icy ocean disguises the craters. It is the one with the lowest density of Galileo's four satellites.
Io: Io is 3,630 km in diameter and turns 421,000 km from Jupiter in just over a day and a half. Its orbit is affected by the magnetic field of Jupiter and the proximity of Europe and Ganymede.
It is rocky, with a lot of volcanic activity. Its global temperature is -143ºC, but there is an area, a lava lake, with 17ºC.
Europe: It is 3,138 km in diameter. Its orbit is located between Io and Ganymede, 671,000 km from Jupiter. Go around every three and a half days.
The appearance of Europe is that of an icy ball with marked lines on the surface of the satellite. They are probably fractures of the crust that have been refilled with water and frozen.
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