Saturn's largest moon, Titan, resembles an Earth you might find in a parallel universe.
It is a mysterious and intriguing moon because it's the only other world we currently know of that has liquid on its surface. It has its own "water cycle" and its poles show an abundance of glistening lakes. It's just that those lakes aren't full of good ol' H2O, like down here on Earth. Instead, they're mostly made up of liquid methane.
And weirdly enough, it seems like some of them are just up and vanishing.
That's according to a new study, published April 15 in Nature Astronomy, that assessed the lakes at Titan's north pole, using data from NASA's Cassini spacecraft, which was equipped with a RADAR instrument and infrared imager.
A team of researchers from Johns Hopkins Applied Physics Laboratory and NASA's Jet Propulsion Laboratory studied images from Cassini's flyby in 2006, noting the presence of dark patches across the northern hemisphere -- the methane lakes. Titan takes almost 30 Earth years to complete one year around the sun, so its seasons are drastically longer than what we are used to on Earth.
When the team went back and looked at the same region in 2013, Titan had moved on from its-length winter and into spring. Three particular dark patches that signified liquid upon the surface were no longer visible. The so-called "phantom lakes" had disappeared.
The research team suggests the phantom lakes could be ponds that are only inches deep and may provide an example of the seasonal cycles that Titan experiences and the way that climate changes as it makes its way around the sun. And though Titan has been floated as a potential place where life may have found a way to thrive, these short-lived lakes are, according to the paper, "nutrient-poor". That makes a bad place for aliens to call home.
The current issue of Nature Astronomy also features another paper describing Titan's unusual methane lakes in the April 15 edition, whereby a team used Cassini's RADAR to show some just how deep some of the northern lakes go. They found that they could exceed up to 100 meters in depth
NASA's Cassini spacecraft, which launched in 1997 and reached Saturn in 2004, observed the ringed planet and its moons over the course of 13 years. It was sent hurtling into Saturn on Sept. 15, 2017, burning up in the atmosphere. The space agency is currently mulling over a new proposal to send a drone, known as Dragonfly, to study Titan in greater detail.