It’s been thought for some time that Saturn’s largest moon Titan has a complex internal structure consisting of multiple layers of ice and liquid water. At one point it was even suggested that there are water ice “cryovolcanoes” on Titan, where watery slush oozes to the surface and freezes solid in the moon’s 270-degree-below temperatures, in very much the same way that liquid rock does on Earth. Now, thanks to recent gravitational observations by Cassini (and who else?) some researchers think that Titan’s icy shell may be much thicker in places than once thought, making the existence of ice volcanoes and Earthlike plate tectonics much less likely.
Although surface temperatures on Titan are cold enough that methane can exist as a liquid, filling lakes and flowing in streams, it may sometimes get so cold that even the liquid methane and ethane freezes, forming floes and icebergs of frozen hydrocarbons. This Titanic revelation was announced today during the 221st American Astronomical Society meeting in Long Beach, CA.
Who says Mercury’s too hot to be really cool? Even three times closer to the Sun than we are, lacking atmosphere and with scorching daytime temperatures of 425 ºC (800 ºF), Mercury still has places more than cold enough to hide ice. This is the most recent announcement from the MESSENGER mission team: (very nearly) confirmed ice on the first rock from the Sun!
Although made mostly of ice and rock, Saturn’s moon Dione (pronounced DEE-oh-nee) does have some color to it — although mostly chilly hues of steel blue, as seen in this color-composite made from raw images acquired by Cassini on July 23.
New research on Jupiter’s ice-covered moon Europa indicates the presence of a subsurface lake buried beneath frozen mounds of huge jumbled chunks of ice. While it has long been believed that Europa’s ice lies atop a deep underground ocean, these new findings support the possibility of large pockets of liquid water being much closer to the moon’s surface — as well as energy from the Sun — and ultimately boosting the possibility that Europa could harbor life.
“Now we see evidence that it’s a thick ice shell that can mix vigorously, and new evidence for giant shallow lakes. That could make Europa and its ocean more habitable.”
– Britney Schmidt, Institute for Geophysics, University of Texas at Austin
Cassini captured this visible-light image on October 16, 2010, showing a thick clump of icy material in Saturn’s bright F ring casting a “fan” of thin shadows. Clumps like this have been seen many times before and may be caused by the gravitational effects of passing shepherd moons like Prometheus or as-of-yet undiscovered moonlets within the ropy rings themselves.
Click here to see how the 63-mile-wide Prometheus can pull streamers of the F ring away as it dips in and out along the course of its scalloped orbit.
Positioned just outside the extreme outer edge of Saturn’s A ring system, the F ring is made up of very bright particles of ice loosely organized into ropy strands and transient clumps. It ranges anywhere from 20 to 300 miles wide.
Image: NASA / JPL / Space Science Institute