Earth was thought to be the only planet in the solar system with liquid water capable of sustaining life. But space scientists now understand this is not the case, following decades of missions by US space agency NASA. And NASA is increasingly confident one of these watery-like worlds, Saturn’s moon Titan, could support alien life.
Titan is a world where rain, lakes and oceans are an everyday feature.
But although similar in this respect to Earth, Saturn’s moon is in fact totally alien, as its surface is saturated with liquid methane.
This incredible observation was made in 2017, before NASA’s Cassini spacecraft hurtled into Saturn’s atmosphere.
This eerily familiar environment was the first sighting of liquid currently on the landscape, instead of evidence of past liquid features.
Dr Rosaly Lopes, a NASA planetary scientist not involved in the study, said “Titan is the only world outside the Earth where we see bodies of liquid on the surface.
READ MORE: NASA in alien life BREAKTHROUGH after DNA discovery
“Some of us like to call Titan the Earth of the outer solar system.”
Dr Shannon MacKenzie, of Johns Hopkins University’s Applied Physics Laboratory, added: “Titan is the most interesting moon in the solar system.
“I think that gets me some enemies, but I think it is actually true.”
However little about Titan is quite what it seems.
For example, features that initially appeared to be liquid-filled lakes when first discovered, now appear to have dried-up.
READ MORE: CERN’s hunt for matter’s ‘EVIL TWIN’ valued at £50 TRILLION per GRAM
This surprise finding suggests the liquid either evaporated or seeped into the surrounding planetary surface.
These “phantom lakes” may be evidence of seasonal changes on the moon, MacKenzie and her coauthors believe.
But the situation may not even be quite that straight-forward, since the observations were taken by different instruments.
So the scientists had to factor in the change in instruments as a potential variable.
But the scientists remain sanguine that something is different in the two passes, and that it’s pretty plausible that liquid was there, then disappeared.
READ MORE: Hunt for aliens ‘only just BEGINNING’ says top scientist
And even if there remains another reason for the phenomena, the strange moon remains extremely intriguing and a strong candidate for being a home to alien life.
Dr MacKenzie said: “If we’re instead looking at some newly identified materials on the surface, then that’s interesting, too, because the sediments on Titan are really important for prebiotic chemistry.”
Dr Marco Mastrogiuseppe, a Caltech planetary scientist, had already measured the depths of some of Titan’s seas, and the Cassini team hoped he would be able to do the same with lakes.
And Dr Mastrogiuseppe has now calculated the depths of lakes more than 328ft (100m) deep and establishing that their contents were dominated by liquid methane.
He said: “We realised that essentially the composition of the lakes is very, very similar to the one of the mare, of the se.
“We believe that these bodies are fed by local rains and then these basins, they drain liquid.”
This suggests Titan may host yet another feature reminiscent of Earth: caves.
Dr Lopes said: “Titan is really this world that geologically is similar to the Earth, and studying the interactions between the liquid bodies and the geology is something that we haven’t really been able to do before.”