Saturn’s main moon, Titan, has a “magic island” that 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 in Titan’s northern polar region. The sea is probably 100 to 200 meters deep and frigid, about –183° to –193° Celsius.
The sea may also be stratified, with more ethane in the deeper layers and methane near the surface. If currents occasionally pull methane down to the deeper sea, the methane and ethane can mix, simulations by Daniel Cordier of the University of Reims Champagne-Ardenne in France and colleagues suggest. Nitrogen doesn’t like this combo, so the gas would separate out of the liquid, fizzing back to the sea surface in centimeter-sized bubbles.
Cassini had one last chance to search for signs of bubbles or some other explanation for the island when it flew by Titan a final time on April 22 (SN Online: 4/21/17).