Titan, Saturn’s giant satellite, is more Earth-like than previously thought.
Previous observations have shown that Titan has a dense atmosphere and stable liquid on its surface.
Of course, its seas and lakes are not made of water, but methane and ethane.
Now, researchers have found a new way in which this distant alien satellite looks disturbingly like our planet: it has sea level, a constant average elevation in relation to gravitational attraction.
The new study, based on data from NASA’s Cassini spacecraft and published in the journal Geophysical Research Letters, finds that Titan’s seas are constantly rising relative to their gravitational pull, just like Earth’s oceans.
It seems that the smallest lakes on Titan appear at elevations several hundred meters higher than sea level.
On Earth, lakes are also commonly found at high altitudes.
The highest lake navigable by large ships, the Titicaca, located at more than 3,700 meters above sea level.
The new study suggests that elevation is important because Titan’s liquid bodies appear to be connected below the surface in something like an aquifer system on Earth.
The hydrocarbons seem to flow below the surface of the moon in a similar way as water flows through porous underground rock or gravel on our planet, which means that nearby lakes communicate with each other and share a common liquid level.
“We’re measuring the elevation of a liquid surface on another body 10 astronomical units away from the sun to an accuracy of roughly 40 centimeters,” explains Alex Hayes, of Cornell University (New York).
“Because we have such amazing accuracy we were able to see that between these two seas the elevation varied smoothly about 11 meters, relative to the center of mass of Titan, consistent with the expected change in the gravitational potential. We are measuring Titan’s geoid. This is the shape that the surface would take under the influence of gravity and rotation alone, which is the same shape that dominates Earth’s oceans.”
Much of the study was based on the data obtained by the Cassini radar instrument.
A new topographic map published in Geophysical Research Letters offered new insight into Titan.
The map exposed several new features on Titan, including new mountains, none of more than 700 meters in elevation.
It also offered a global view of the highs and lows of its topography, which allowed scientists to confirm that two places in the equatorial region of Titan which are in fact depressions that could be ancient dry seas or cryovolcanic flows.
The map also revealed that Titan is a bit more flattened than previously known, suggesting that there is more variability in the thickness of its crust than previously thought.
Despite the fact that we have learned much about Titan in recent years, only 9 percent of Titan has been mapped in high-resolution, while around 30 percent was imaged in lower resolution.
Featured image credit: Shutterstock.