For a while there, it seemed like Pluto was doomed to be the outcast of our solar system after its planetary status was stripped in 2005. However, Pluto has since been the subject of a number of surprising discoveries, showing that big things indeed can come in small packages.
Earlier this year, astronomers published data claiming that Pluto might be able to host a liquid ocean on its surface. Since then, Pluto began mysteriously shooting out x-rays without any plausible explanation that matches current models of planetary science. While that one is still unexplained, the ocean theory might have just been proven to be spot on thanks to two studies recently published in Nature.
Both of the articles are based on surveys of the Sputnik Planitia, a massive 1300-kilometer long (800-mile) impact basin in Pluto’s icy Tombaugh Regio. The crater, being devoid of mass, would have normally caused the planet to tilt towards more massive areas around the equator. According to one of the Nature publications, this represents a “gravity anomaly” that indicates some hidden mystery beneath the former planet:
Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin’s present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography.
Instead of Pluto tilting away from the basin, astronomers discovered that the opposite actually occurred, indicating some sort of mysterious mass underground to keep Pluto oriented in this unusual way. Further data reveals the presence of cracks that indicate stresses on the planet’s surface as a result of a re-tilting at some point in the planet’s past. According to the second of the Nature publications, these two factors indicate the likely presence of a subsurface liquid ocean:
The combination of this reorientation, loading and global expansion due to the freezing of a possible subsurface ocean generates stresses within the planet’s lithosphere, resulting in a global network of extensional faults that closely replicate the observed fault networks on Pluto.
It’s long been assumed that liquid oceans could be a key a necessary ingredient for life on alien worlds, so this discovery gives some hope to the search for life in the Universe.
And hey, NASA's already working on that neato space submarine. Underwater battles with deadly laser-eyed space squids, here we come.