Saturn’s moon Titan continues to be one of the most fascinating places in the Solar System. Alongside its Earth-like weather system and possible underground ocean, it is the only place other than Earth known to have bodies of liquid on the surface. And in one of its seas, a mysterious feature is puzzling scientists.
This feature, dubbed the “magic island,” was spotted in images from 2013 and 2014 taken by the Cassini spacecraft. It appears near the coast of Titan’s second-largest body of liquid, Ligeia Mare, and measures about 260 square kilometers (100 square miles) in size – roughly the size of Washington, DC. The lake itself is 130,000 square kilometers (50,000 square miles).
But mysteriously, the feature is not present in radar images taken in 2007 nor, most recently, on January 11, 2015 in an image released by NASA yesterday. This suggests that Titan’s seas, composed of liquid hydrocarbons such as methane, are active.
“Now we have confirmation that these seas are not stagnant ponds just sitting there, but there is activity in them,” said Jason Hofgartner of NASA’s Jet Propulsion Laboratory, reported New Scientist.
The feature is seen here in 2013 and 2014, but not in other years. NASA/JPL-Caltech/ASI/Cornell
Perhaps most baffling of all, though, is that we don’t know what is causing the feature. The predominant theory at the moment is that it is waves moving slowly on the surface of Titan. It has already been theorized that tiny waves, less than a meter tall, might be moving on Titan’s seas at a sedate one meter per second. This feature could be the first direct evidence for such waves.
Other theories abound, though. The feature could be the result of bubbles rising up from the depths of Ligeia Mare, which is up to 170 meters (560 feet) deep in places. It could also be some sort of solid material dislodged from the bottom of the sea, temporarily rising up before sinking down again.
The waves theory is supported by the fact that the moon’s Northern Hemisphere, where the sea is located, is entering its summer, with Titan’s year lasting 30 Earth years. Winds are expected to pick up during the summer, possibly giving rise to waves like this.
In April 2017, Cassini will make its next and final observation of its region, before it is sent plunging into Saturn’s atmosphere later that year. Scientists will be eagerly awaiting more images to see if this feature has returned.