A team of planetary researchers, led by Jason Hofgartner of Cornell University, has announced the discovery of an anomalous, bright geologic object – where one never existed – in Titan’s norther polar sea, Ligeia Mare.
Discovered in 1655 by Dutch astronomer Christiaan Huygens, Titan is the largest of the Saturn’s known 62 moons.
Titan is the second largest moon in our Solar System and the only moon known to have clouds and a thick, planet-like nitrogen-methane atmosphere. It bears close resemblance to Earth, with wind and rain driving the creation of strikingly familiar landscapes.
Under its hazy atmosphere, scientists have found mountains, dunes, lakes and seas, including Ligeia Mare – the second-largest sea on Titan.
The newly discovered geologic feature, dubbed the ‘Magic Island,’ was detected in Ligeia Mare by NASA/ESA Cassini spacecraft’s Titan Radar Mapper instrument in July 2013.
“This discovery tells us that the liquids in Titan’s northern hemisphere are not simply stagnant and unchanging, but rather that changes do occur,” said Mr Hofgartner, who is the first author of a paper published in the Nature Geoscience.
“We don’t know precisely what caused this Magic Island to appear, but we’d like to study it further.”
Prior to the 2013 observation, the region of Ligeia Mare had been completely devoid of features, including waves.
The scientists speculate on four reasons for the Magic Island:
(i) northern hemisphere winds may be kicking up and forming waves on Ligeia Mare. The radar imaging system might see the waves as a kind of ‘ghost’ island;
(ii) gases may push out from the sea floor of Ligeia Mare, rising to the surface as bubbles;
(iii) sunken solids formed by a wintry freeze could become buoyant with the onset of warmer temperatures during the late Titan spring;
(iv) Ligeia Mare has suspended solids, which are neither sunken nor floating, but act like silt in a terrestrial delta.
“Likely, several different processes – such as wind, rain and tides – might affect the methane and ethane lakes on Titan. We want to see the similarities and differences from geological processes that occur here on Earth. Ultimately, it will help us to understand better our own liquid environments here on the Earth,” Mr Hofgartner concluded.
J.D. Hofgartner et al. Transient features in a Titan sea. Nature Geoscience, Published online June 22, 2014; doi: 10.1038/ngeo2190