5 Unsolved Mysteries of Our Solar System's Moons
- Thread starter Rhykker
- Start date
Gotta agree with you there! We've barely scratched the surface. Heck, most of these moons were discovered in the past 10 years or so!Halyah said:
Cheers! Glad you could learn a thing or two. I think everyone should challenge themselves to learn something new every day.Nimcha said:
If you think the moons are trying to screw with your mind, ask Saturn about its hexagon-shaped storm [http://en.wikipedia.org/wiki/Saturn's_hexagon] sometime.Halyah said:
Europa scientist here! Let's take a look-see, shall we?
Actually, the liquid ocean most definitely exists beneath it, as evinced by the induced magnetic field measured by the Galileo probe, shown to be due to the flow of ions in solution less than 100 km from Europa's surface. Most computer models that take into account the heat generated by tidal flexure suggest that Europa's ice shell is approximately 20 km thick; including my own work on the subject.
This is most likely incorrect. Europa in its current state (ever since it's been locked in orbital resonance with Ganymede and Io) does not have enough ocean pressure for extrusive cryovolcanism (i.e. water eruptions) to take place. This is in contrast to a satellite like Enceladus, whose ice shell is thick enough that the water underneath is overpressurized enough, due to ice's expansion as it freezes, to have gigantic water eruptions centered around its south pole. A model one of my friends is working on is investigating whether intrusive cryovolcanism may form Europa's ridges, in which water rises part way through the shell, freezes and expands there, and then buckles it. Results look promising.
The criss-crossing lineae are probably best explained, as you said, by the ice shell's non-synchronous rotation. There's actually been a few fascinating studies on what the concurrent tidal stresses and non-synchronous rotation put Europa's shell through. The principal direction of stress on Europa's shell is in constant flux, which causes fractures to form frequently in any direction, often overwriting earlier landmarks and fractures. I've seen some really nifty animations of what this evolving stress field looks like, but alas, I cannot dig them up. These features on Europa, however, called cycloids, clearly illustrate the effects of tidal stresses on a freely rotating spherical surface:
The cycloids can be seen in this picture as parallel bands that form prominent arcuate curves. I don't know too much about the specific mechanisms that form them, as my specialty is in modeling the thermodynamics of the entire ice shell rather than the formation of surface features, but I think they propagate along the principal direction of tidal stress as it changes over time.
The cycloids can be seen in this picture as parallel bands that form prominent arcuate curves. I don't know too much about the specific mechanisms that form them, as my specialty is in modeling the thermodynamics of the entire ice shell rather than the formation of surface features, but I think they propagate along the principal direction of tidal stress as it changes over time.
