Earth, Mars, Titan. They might all seem pretty different, but all three have got a surprising amount in common. And now we can add one more thing to the list.
Using data from NASA’s Cassini spacecraft, which was sent to its fiery demise last year, scientists have discovered huge dust storms on Saturn’s moon Titan. This makes it only the third place in the Solar System we know to have these features.
The research describing this finding is published in the journal Nature Geoscience, led by Sebastien Rodriguez from the Université Paris Diderot in France.
"We already know that about its geology and exotic hydrocarbon cycle,” Rodriguez said in a statement. “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."
Looking at infrared images from Cassini, the team spotted three unusual brightening events about 10 kilometers (6 miles) above the surface near the moon’s equator during its equinox in 2009 and 2010 – when the Sun crosses the equator. They appeared right over Titan’s dune fields, lasting for up to five weeks, suggesting they were clouds of dust.
The team ruled out other options, such as these being methane clouds. We know the moon has clouds, fed by its lakes and seas, but these brightening features were too low to be related. They also ruled out frozen methane rain or icy lavas. Instead, they think strong winds on Titan must have kicked up dust from the surface.
These strong winds would be five times those measured by the Huygens lander in 2005, but they could be possible thanks to rare methane storms. These create downdrafts that produce large gusts, and have been linked to the formation of Titan’s moons before.
“Gusts have the highest probability of occurring during equinox in the equatorial regions, precisely when and where we possibly observe the dust storms,” the team wrote in their paper.
This in itself may explain why seeing dust storms on Titan has been so difficult. Titan takes 29.5 years to orbit the Sun, so it only experiences an equinox every 14.7 years. With these dust storms lasting as little as 11 hours and a maximum of five weeks, that gives us an incredibly short window to see them.
Titan’s next equinox will be in about 2024, but unfortunately we won't have a spacecraft in orbit ready and waiting to watch them again. Still, the discovery paints Titan in a slightly new light.
Mars has been recovering from a global dust storm recently, while Earth also experiences its fair share. Adding Titan to the list gives another way that it is active and changing, a place not too unlike home.