As astronomers weekly announce the discovery of new exoplanets – some similar in size or temperature to our home planet – it can be good to remember that Earth-like worlds are not always far away.
While Saturn’s largest moon, Titan, is a small cold world orbiting on the outskirts of the solar system, it actually boasts many familiar features.
“Titan is fascinating because it has properties so similar to Earth,” said planetary scientist Oded Aharonson from the California Institute of Technology. “It has a liquid into which to dissolve things, an atmosphere, a hydrologic cycle, and many other parallels.”
Chief among Titan’s interesting qualities is that it is the only body other than Earth where liquids are known to flow in large concentrations on the surface. Because average temperatures there are -300 degrees Fahrenheit, these liquids are not water. Instead, hydrocarbons such as methane and ethane rain down from clouds, course over the landscape in rivers and eventually pour out into large lakes and seas.
The presence of liquids has sparked scientists’ imagination. If Titan has so many Earth-like features, they say, perhaps it possesses one more terrestrial trait: the presence of life. Titan organisms would be an incredible discovery, showing that life formed more than once and suggesting it is common in the universe.
In this gallery, Wired looks closer at the details of this strange wet world so similar and so different from our own.
Above:
Sea of Ligeia
Creatively colored in this image, Ligeia Mare looks like an inviting place for a summer vacation. Ligeia is one of Titan’s largest lakes, with a surface area bigger than Lake Superior, located in the planet’s northern high latitudes.
The radar data for this picture came from NASA’s Cassini spacecraft, which has been in orbit around Saturn since 2004. Around the edges, many channels are visible. Rivers of hydrocarbons carved these channels, in much the same way that the Colorado River etched out the Grand Canyon.
Image: Antoine Lucas, Oded Aharonson & The Cassini Radar Science Team, Caltech/JPL/NASA