The far northern reaches of Titan, Saturn’s largest moon, might feature seasonal lakes that vanish between winter and spring.
Studying images taken by NASA’s Cassini spacecraft in 2006, Shannon MacKenzie at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and her colleagues spotted three dark patches during Titan’s winter, indicating the presence of lakes. When the spacecraft photographed the area again in 2013, after Titan’s spring equinox, the land was lighter in colour — suggesting that the lakes had dried up in the interim. These ‘phantom lakes’ might have been shallow ponds that were just a few millimetres deep.
Another research team used Cassini’s radar to probe several different northern lakes in April 2017, which turned out to be rich in liquid methane and more than 100 metres deep. They might have formed as methane rains on the moon dissolved rocks at its surface, says a team led by Marco Mastrogiuseppe at the California Institute of Technology in Pasadena.
Together, the studies show how Titan’s lakes evolve over time. If some of Titan’s lakes evaporate seasonally, they will be a less intriguing place to look for extraterrestrial life than in permanent bodies of liquid.