Question

List the major satellites of Jupiter & Saturn. Briefly indicate some of their properties &/or why they are of particular interest

Answer 1

Well there are total 89 moons of jupiter while Saturn has 82 moon in which 53 moons are confirmed and named and another 29 moons are awaiting confirmation of discovery and official naming. There are the four largest moons of Jupite - Io, Europa, Ganymede, and Callisto which are called galilean moons.

They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with radii larger than any of the dwarf planets. Ganymede is the largest moon in the Solar System, and is even bigger than the planet Mercury, though only around half as massive. The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1 orbital resonance with each other. Because of their much smaller size, and therefore weaker self-gravitation, all of Jupiter's remaining moons have irregular forms rather than a spherical shape.The Galilean moons were observed in either 1609 or 1610 when Galileo made improvements to his telescope, which enabled him to observe celestial bodies more distinctly than ever. . The discovery of celestial bodies orbiting something other than Earth dealt a serious blow to the then-accepted Ptolemaic world system, a geocentric theory in which everything orbits around Earth.

Titan Dione. Enceladus Hyperion Iapetus.Mimas.Rhea Tethys are the major moons of saturn. One of Saturn's moons, Titan, makes up 96 percent of the mass orbiting the planet. Scientists think that Saturn's system may have originally housed two such moons, but the second broke up, creating the debris that formed the rings and smaller, inner moons. Another theory suggests that the system originally housed several large moons, similar to Jupiter's Galilean moons, but two fused into Titan. The violent collision could have scattered the debris that would have later drawn together into the smaller moons .Dione is thought to be a dense rocky core surrounded by water-ice. The tidally locked moon is heavily cratered not on its leading side but on its back side. Astronomers think a collision could have spun the moon on its axis.Enceladus contains more than 100 geysers at its south pole. Tidal heating causes portions of the icy planet to melt, spewing icy material into space from its "tiger stripes.The tiny bits of ice travel together to create Saturn's E ring. The satellite's icy surface makes it one of the brightest objects in the solar system. The moon has a subsurface ocean that may be friendly to life.Hyperion was the last of the major satellites to be discovered. Hyperion is a small moon with an irregular appearance. The flattened object resembles an elongated potato rather than a sphere, a form that may have been created when an impact demolished a larger moon long ago. Iapetus features light and dark contrasts on its surface, giving the moon a yin-yang shape. Dark hydrocarbons falling to the moon long ago, perhaps from the nearby moon Phoebe, may have had more time to absorb more heat, gradually growing and spreading over time. Iapetus has a walnut-like shape, with its center bulging outward, and a ridge running around its equator.Mimas has a gaping crater that gives the rocky moon a strong resemblance to fictional Death Star in the "Star Wars" movies. The impact stands out despite the fact that Mimas is one of the most heavily cratered bodies in the solar system, with overlapping impacts covering the surface. The smallest and closest orbiting of Saturn's major moons, Mimas cleared the gap known as the Cassini division between two of the planet's rings.Rhea is a heavily cratered moon and lacks a core at its center. Instead, the entire body is composed of ice, with traces of rock mixed in, causing it to resemble a dirty snowball. The second largest of the planet's major moons, Rhea is still rather small, about half the size of Earth's moon. The satellite contains a faint oxygen atmosphere, about 5 trillion times less dense than the one found on Earth, but the only known oxygen atmosphere in the solar system.Tethys travels close to Saturn and feels the gravitational pull of the planet. The heat from Saturn may allow the moon's icy surface to melt slightly, filling in craters and other signs of impact. Made up almost entirely of water ice, the surface is highly reflective.