Planetary Moons Flashcards
named for the mythical boatman of the greek underworld. the largest moon relative to the size of its orbiting planet, not only is in synchronous orbit with Pluto, bu the two show the same face toward each other at all times. the relative sizes of the two bodies has led some to call it and pluto a double planet system. surface is believed to be water ice
Charon (pluto)
named for two sons of ares and Aphrodite. greek for fear and panic, the two moons of mars were discovered in 1877 by asaph hall. unlike the earth’s moon, it rises in the west and sets in the east, about 2x per martian day. this is due to it being below the radius for synchronous orbit. this position also means it will either impact mars or break into a ring in around 50 million years.
deimos and phobos (mars)
one of the Galilean moons, discovered in 1610 by galileo. it resembles io, and to a degree, earth, in its composition of silicate rocks. however, it is coated in a thin layer of ice, which causes it to be exceedingly smooth. this ice layer may also provide a thin atmosphere as hydrogen and oxygen are released when the planet is exposed to sunlight. there is the possibility of an active sea of liquid water beneath the surface. the most striking feature of the surface is a series of dark streaks that may be due to geysers or volcanic eruptions
Europa (Jupiter)
largest satellite in the solar system, this moon is larger than mercury, but has only half its mass. based on the observations of the galileo spacecraft, it is thought to have a 3 layer structure of a molten iron core, silicate mantle, and ice exterior. its surface is marked by older, dark, highly cratered regions, mixed with lighter, grooved regions. these grooves indicate tectonic activity, but it does not appear to have undergone recent tectonic shifts
Ganymede (Jupiter)
like Europe, (named for a lover of zeus) it is primarily formed of silicate rock. its surface, however, is unlike any other satellite. rather than craters, it is dotted w/ active volcanoes, calderas, and other signs of geological activity. the eruptions are believed to consist of sulfurous compounds and that comprise its thin atmosphere. the tremendous activity is due to tidal warming from the gravity of Jupiter and other satellites. additionally, as it orbits it is heated electrically from currents produced by Jupiter’s magnetic field. this action strips material from it, producing a radiation field and increasing Jupiter’s magnetosphere
io (Jupiter)
discovered by Gerard Kuiper (who also discovered Miranda, Titan’s atmosphere, and an asteroid belt), it (named for the dauters of nereus and doris) has the most eccentric orbit of any known satellite, ranging from 1.3 million km to 9.6 mil. the oddity of this orbit indicates it is likely a captured asteriod
nereid (Neptune)
named for the king of the fairies in a middsummers night’s dream (all of Uranus’ satellites are named for literary, rather mythological, characters), it is both the 2nd largest of uranus’ satellites, and the outermost of its large satellites. like all large uranian moons, its structure is about half water ice, half rock. large faults are visible across its southern hemisphere, but its surface is heavily craterted, indicating long-term tectonic stability. some craters have dark floors that could possibly indicate post-impact upwellings of water
oberon (Uranus)
largest of Saturn’s satellites, it MIGHT be the largest satellite in the solar system, but this awaits more accurate measurements. those measurements are difficult because of its major characteristic: it is the only satellite to have a substantial atmosphere. its significant atmosphere, a mix of nitrogen (80%), methane (20%), and argon (trace), also make it unique among satellites
titan (Saturn)
another of Herschel’s discoveries, titania is named for oberon’s wife, the queen of the fairies, and is the largest of the uranian satellites. its surface is an odd mix of craters and valleys. one theory regarding this is that it began as a liquid, then cooled surface first. once ice had formed, the interior, freezing forced surface cracks which formed the valleys. this also accounts for the appearance of some craters, where ice appears to have melted and filled in
titania (Uranus)
by far the largest of Neptune’s satellites, it is also unusual for its retrograde orbit, which indicates that it was not part of the natural formation of Neptune’s other moons. it also features seismic activity in the form of ice volcanoes, a tenuous nitrogen-methane atmosphere, and a southern hemisphere “ice cap” of nitrogen and methane. all of these may be caused by its odd rotational axis, which tends to altername polar and equatorial regions facing the sun
triton (Neptune)
