schneiderism

This is not breaking news, as it dates back to March of this year, but I was excited to read about it earlier this morning. The Cassini team issued a report last March that demonstrated the evidence of a liquid ocean beneath the surface crust of Saturn’s moon Titan. The interesting revelation is that this ocean is thought to be “global” on the moon, and as such indicates that the entire surface crust of Titan is decoupled from the interior of the planet, floating on this ocean. The evidence for this is based on the measurements of how Titan’s crust slides as a result of forces exerted by its atmosphere, as much as a .36 degree shift measured over the course of a year. That is considered to be pretty significant movement.

There is a great article about this at The Planetary Society, and it reports that the empirical evidence of the ocean on TItan, already long suspected by scientists, lends credence to the theory that several other icy bodies in our solar system also have hidden interior oceans. Jupiter’s moons Europa, Callisto, and Ganymede are the most probable candidates for this phenomenon. The image above illustrates the proportion of the internal make-up of several of these satellites, and the relationship between these proportions and the existence of an internal ocean. It is thought by scientists that the existence of oceans in icy satellites may be a common occurance in our solar system.

I subscribe to the NASA RSS feed for the Cassini-Huygens mission and just came upon this image taken back on June 10th of this year. This simple black and white image taken by Cassini conveys so much detail about the icy moon. There is the surface, riddled with impact craters and covered in ridges and striations. If you look at the upper right edge of the moon silhoetted against the blackness of space you get a sense of the dimensionality of the moon’s surface. Rhea is the second largest of Saturn’s moons at about 950 miles across, this image definitely gives it presence. Some more detail on Rhea:

• Rhea was discovered in 1642 by Giovanni Cassini, the namesake for the Cassini space probe and the astronomer who also discovered the Saturn moons Iapetus, Dione, and Tethys
• In direct sunlight the temp is as warm as -281°F, and in the shade -364°F
• Rhea has a rocky core that is about one-third of its mass, the rest is water-ice
• It is about 527,000 km from Saturn