Earth's Moon Reveals An Ancient Secret. Many astronomers think that during an ancient era, termed the Late Heavy Bombardment, our young Moon was violently battered by a marauding multitude of invading asteroids that crashed onto its newly formed surface. This attack of pelting objects from space occurred about 4 billion years ago, and the shower of crashing asteroids excavated impact craters, and also slashed open deep fissures, in the lunar crust. This sustained shower of merciless impacts increased lunar porosity, and opened up an intertwining network of large seams under the Moon's surface.
But small moons like Methone are usually geologically inactive and bereft of an atmosphere. Therefore, they are usually unable to smooth away the scars. Dr. Peter Thomas of Cornell University in Ithaca, New York, explained it this way in the May 17, 2013 New Scientist: "When we look at objects less than 200 kilometers in radius, they are all like potatoes. They have lumps, grooves, craters." This makes Methone's smooth surface a mystery. Dr. Thomas is a Cassini team member.
Organic dust forms when organic molecules, resulting from the interaction of sunlight with methane, grow large enough to tumble down to the surface of Titan. Dr. Roderiguez continued to explain that, even though this is the first-ever observation of a dust storm on Titan, the discovery is not especially surprising.