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Weird feature on Titan could point to arrival of summer

Elizabeth Howell, News Writer
Oct 1, 2014, 14:41 UTC

Sen—Is this a sign of Titanian summer? Scientists are puzzled about a fluctuating feature on Saturn's largest moon. While they don't know what the 260-kilometre-square feature in a huge sea is, they speculate it might be due to changing seasons.

"Scientists on the radar team are confident that the feature is not an artefact, or flaw, in their data, which would have been one of the simplest explanations," NASA stated in a press release. "They also do not see evidence that its appearance results from evaporation in the sea, as the overall shoreline of Ligeia Mare has not changed noticeably."

The mystery has been known for a little more than a year, when Cassini spacecraft scientists reviewing radar images found a bright spot in Ligeia Mare, a hydrocarbon sea on Titan's surface. Titan is considered to have prebiotic (pre-life) chemistry that includes elements such as methane and ethane. It is the only moon in our Solar System known to have an atmosphere and liquid cycle, two characteristics it shares with Earth.

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Astronomers are puzzled by Cassini images of this mysterious, evolving feature in Ligeia Mare—a huge hydrocarbon sea on Saturn's moon Titan. Image credit: Arizona State University

The data first came to light after Cassini made a flyby of Titan in July 2013. A few months later, new images of the area showed that the feature had vanished again. Then it reappeared in images from 21 August, 2014, when Cassini once again swung by Saturn's largest moon.

Cassini scientists are unclear on what is happening, but they have several hypotheses: waves, bubbles, solids or "perhaps something more exotic", NASA said.

"Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan," said Stephen Wall, the deputy team lead of Cassini’s radar team at NASA’s Jet Propulsion Laboratory in California.

Recording of a Google Hangout discussing the Cassini mission. Credit: NASA

“We’re hopeful that we’ll be able to continue watching the changes unfold and gain insights about what’s going on in that alien sea."

Cassini has been operating around Saturn and its moons since 2004 and is now working well into overtime after its first four-year mission. The spacecraft is now slated to operate until at least 2017, long enough to watch the northern hemisphere of Titan slip into summer.

NASA says that Titan is a "top priority" for observations due to changes on its surface such as flooding, lake levels rising and volcanic activity.