‘Hot cross bun’ on Titan may indicate subsurface geological activity

Comparison of the “hot cross bun” feature on Titan with a similar volcanic mound on Venus. Credit: NASA

With its methane lakes, rivers and rain, Titan is already one of the most fascinating worlds in our solar system, with intriguing parallels to Earth despite the much colder climate.

But what is happening below the surface? Does Titan also have geological activity like Earth does? There has been tantalizing evidence for possible cryovolcanism (ie. ice volcanoes), where ice plays the role of magma, but nothing more definitive so far.

Now, new radar images of Titan’s surface from the Cassini spacecraft have revealed an odd feature that may be the best evidence so far. The circular mound in the northern hemisphere resembles a hot cross bun, with near-perpendicular cracks crossing over it like a cross. About 70 kilometres (43 miles) in diameter, it is similar to some volcanic features seen on Venus.

Like on Venus, the mound and its cracks are thought to be caused by the upwelling of magma from below. It is also reminiscent of the Henry Mountains in Utah, which are laccoliths and formed by a similar process. In Titan’s case though, the magma may actually be cryomagma instead of the hot, steaming magma we are most familiar with.

According to Rosaly Lopes, a Cassini radar team scientist, “The ‘hot cross bun’ is a type of feature we have not seen before on Titan, showing that Titan keeps surprising us even after eight years of observations from Cassini.”

Titan is also now thought to possibly have a subsurface ocean of water deep down, but whether this has any connection with the “hot cross bun” feature is as yet unknown.

The new findings were presented last Tuesday at the American Astronomical Society’s Division of Planetary Sciences conference in Reno, Nevada.

This article was first published on Examiner.com