For the first time ever, NASA's Cassini spacecraft spotted a huge dust storm in the equatorial regions of Titan, Saturn's largest moon.
Aside from Earth, only one other cosmic body is known to host dust storms: Mars.
Until now, that is.
In a paper published in the journal Nature Geoscience, scientists analyzed Cassini data to reveal that Titan is the third object in the solar system where dust storms have been found.
The Remarkable Titan
Titan has long been the subject of interest by astronomers due to its similarities to Earth. According to NASA, it is the only moon in the solar system with a substantial atmosphere. Furthermore, it's the only other known body where stable surface liquid is still found.
Sebastien Rodriguez, lead study author and an astronomer at the Université Paris Diderot, France, describes Titan as an extremely active moon, which is apparent from the body's geology and hydrocarbon cycle.
"Now we can add another analogy with Earth and Mars: the active dust cycle, in which organic dust can be raised from large dune fields around Titan's equator," he says.
Massive Dust Storms On The Moon
While both Earth and Titan contain liquid bodies, the former features water and the latter's reservoirs contain methane and ethane. When the sun passes by Titan's equator during the equinox, large clouds form and generate strong methane storms, which Cassini was able to detect during flybys.
Scientists initially believed that odd equatorial brightenings in the Cassini infrared data from back in 2009 were these methane clouds. However, Rodriguez says that methane clouds aren't physically possible in the region and season they were seen at. Any methane cloud that would form in these conditions would have properties that are inconsistent with what the models actually show.
After also ruling out frozen methane or icy lavas as well as determining that the atmospheric features are quite near the surface, the researchers concluded that the bright spots are clouds of dust that has been raised from the dunes.
The dust, the authors explain, is made up of organic molecules that was produced by the interaction of sunlight and methane in the moon's atmosphere.
"The near-surface wind speeds required to raise such an amount of dust as we see in these dust storms would have to be very strong — about five times as strong as the average wind speeds estimated by the Huygens measurements near the surface and with climate models," Rodriguez explains.
The authors suggest that the dunes are active and constantly in flux, just like Earth's and Mars'.