Image of Jupiter's largest moon, Ganymede
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Courtesy of NASA
Dust Around Moon Gives Clues to Planetary Rings
News story originally written on June 17, 1999
With the help of Galileo, scientists have discovered new evidence that may explain planetary rings. We already know the rings are made of dust and ice. However, until now scientists only had guesses as to how the rings actually formed.
Galileo has found small grains of dust that are always bombarding celestial bodies. When the high speed particles hit the surface, they throw pieces of debris up into space. Smaller bodies, such as moons, have a gravity just strong enough to hold the particles in orbit. Eventually, the grains form a ring.
The research was conducted while studying Ganymede, the largest of Jupiter's 15 moons. Using a small metal can, scientists could measure the speeds of the meteoroids when they hit the moon.
Unfortunately, this new study fails to shed any light on the formation of Saturn's rings, which are made of big chunks of ice.
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