There are 79 known moons of Jupiter, not counting a number of moonlets likely shed from the inner moons. The four Galilean moons are by far the largest and most massive objects to orbit Jupiter. Of Jupiter’s moons, eight are regular satellites with prograde and nearly circular orbits. Twenty-two of the irregular satellites have not yet been officially named.
About Moons of Jupiter in brief
There are 79 known moons of Jupiter, not counting a number of moonlets likely shed from the inner moons. The four Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 75 known moons and the rings together composing just 0. 003% of the total orbiting mass. Of Jupiter’s moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined with respect to Jupiter’s equatorial plane. Twenty-two of the irregular satellites have not yet been officially named. Jupiter’s regular satellites are believed to have formed from a circumplanetary disk, a ring of accreting gas and solid debris analogous to a protoplanetary disk. Each generation of moons might have spiraled into Jupiter, because of drag from the disk, with new moons then forming from the new debris captured from the solar nebula. The outer, irregular moons are thought to have originated from captured asteroids, whereas the protolunar disk was still massive enough to absorb much of their momentum and thus capture them into orbit. The physical and orbital characteristics of the moons vary widely. The largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets.
Most other Jovian moons are less than 250 kilometres in diameter, with most barely exceeding 5 kilometres. Their orbital shapes range from nearly perfectly circular to highly eccentric and inclined, and many revolve in the direction opposite to Jupiter’s rotation. Orbital periods range from seven hours, to some three thousand times more. The current Galilean satellites were still affected, falling into and being partially protected by an orbital resonance with each other, which still exists for Io, Europa, and Gany mede. GanyMede’s larger mass means that it would have migrated inward at a faster rate than Europa or Io. By the time that the Voyager probes reached Jupiter in 1979, 13 moons had been observed. No additional satellites were discovered until E Barnarda in 1892, Ananke in 1951, Leda in 1974, and Lysithea in 1914, Carmee in 1908, Sinipha in 1914 and Caropee in 1914. In the 20th century, Elara was discovered in 1904, Eliza in 1905, Pasipara in 1905 and Eliza Pasiphae in 1910, Eliphas Pasiphar in 1910 and Elara in 1911.
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This page is based on the article Moons of Jupiter published in Wikipedia (as of Dec. 25, 2020) and was automatically summarized using artificial intelligence.
