Bubbles may put mysterious fizz in Titan’s polar sea

SHAPESHIFTER Nitrogen bubbles may be the source of an on-again, off-again bright spot, or “magic island,” on Saturn’s moon Titan. Cassini spacecraft images of the island, which sits in a hydrocarbon sea called Ligeia Mare, revealed the feature’s fickle nature.

Cornell/ASI/JPL-Caltech/NASA

By Ashley Yeager

April 18, 2017 at 11:00 am

Saturn’s main moon, Titan, has a “magic island,” which might be made of streams of nitrogen bubbles, scientists report April 18 in Nature Astronomy.

Images from NASA’s Cassini spacecraft show that the island, which appears as a bright spot, comes and goes. It sits in Ligeia Mare, a sea made of methane, ethane and nitrogen. The sea, located in Titan’s polar region, is probably between 100 to 200 meters deep and pretty cold, about ‒183 to ‒193° Celsius. The deeper sea layers might be richer in ethane, while more methane sits near the surface. If currents pull methane down to the deeper layers of the sea, the methane and ethane can mix. Nitrogen doesn’t like this combo, so the gas separates out of the liquid, fizzing back to the sea surface in centimeter-sized bubbles, simulations suggest.

Cassini will have one more chance to search for signs of bubbles or some other explanation for the island when it flies by Titan a final time on April 22.