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Titan's Dunes Took Tens of Thousands of Years To Form
sciencehabit writes: Massive dunes, some of them 100 meters tall and a kilometer or more wide at their base, cover about one-eighth of Titan's surface. And they take an exceptionally long time to form, according to a new study. Using radar data gleaned by the Cassini probe when it occasionally swooped past Saturn's haze-shrouded moon, researchers conclude that it would take about 3000 Saturn years (or 88,200 Earth years) to shift Titan's dunes to the extent seen in the images. A similar phenomenon has taken place on Earth, the researchers note: The overall patterns in many large dune fields in the southwestern Sahara and the southwestern United States, shaped by the winds that blew during the most recent ice age more than 10,000 years ago, remain largely unaffected by modern winds that now blow in a different direction.
As a planetary scientist, but mostly working on atmospheres, I have to disagree. This is a very short time for _geological_ processes, but a very long time for processes involving structures of a matter so fine grained that it is easily moved around by wind (sand or with grain size comparable to sand).
At the surface level, the density in molecules per cubic meter of Titan's atmosphere is ~5 times the Earth's atmosphere at sea level, so it does not take much wind (fluid velocity) to move around small grains provided they are not stuck together by some other agent (water on Earth, liquid hydrocarbons on Titan).