High-Altitude Methane Ice Cloud Discovered Floating Above Titan's Pole

NASA scientists have uncovered a starting new find on Saturn's moon, Titan. They've found an unexpected high-altitude methane ice cloud, similar to exotic clouds formed high above Earth's own poles. This cloud in the stratosphere over Titan’s north pole (left) is similar to Earth’s polar stratospheric clouds (right). NASA scientists found that Titan’s cloud contains methane ice, which was not previously thought to form in that part of the atmosphere. Cassini first spotted the cloud in 2006. (Photo : L. NASA/JPL/U. of Ariz./LPGNantes; R. NASA/GSFC/M. Schoeberl)

NASA scientists have uncovered a starting new find on Saturn's moon, Titan. They've found an unexpected high-altitude methane ice cloud, similar to exotic clouds formed high above Earth's own poles.

The researchers first spotted the cloud with the help of NASA's Cassini spacecraft. It was part of the winter cap of condensation over Titan's north pole. Now, scientists have teased apart the data and found that the cloud contained methane ice, which produces a much denser cloud than the previously identified ethane ice.

"The idea that methane clouds could form this high on Titan is completely new," said Carrie Anderson, lead author of the new study, in a news release. "Nobody considered that possible before."

The temperatures in Titan's lower stratosphere are not the same at all latitudes. In fact, the high-altitude temperature near the north pole is far colder than just south of the equator. This temperature difference-as much as 11 degrees Fahrenheit-is enough to yield methane ice.

So how do these clouds form? The mechanisms for forming these high-altitude clouds are different from what happens in the troposphere. Titan has a global circulation pattern; warm air in the summer hemisphere wells up from the surface and enters the stratosphere, slowly making its way to the winter pole. There, the air sinks back down and cools as it descends. This forms the methane clouds.

Currently, the scientists are gathering more information about Saturn's moon in order to better understand the natural processes that occur on the alien world. This could shed light on the processes that occur on exoplanets and allow scientists to apply their findings to processes that also occur on Earth.

"Titan continues to amaze with natural processes similar to those on Earth, yet involving materials different from our familiar water," said Scott Edgington, Cassini deputy project scientist. "As we approach southern winter solstice on Titan, we will further explore how these cloud formation processes might vary with season."