On my nightly walks with the dog, if the skies are cloudy or the glare too bright, I concentrate on the snow and ice on the ground. Like this partially melted snowbank in front of my house. Road salt, car exhaust, and gravel and dirt from the driveway’s edge has dirtied up the once-pristine snowfall. It looked like this last week:
Compare this with Hyperion, moon of Saturn:
No impact craters in my front yard. But I thought the two were similar. Hyperion has about half the density of ice, so if the substance of the moon is mostly ice, about half of it is empty space. Astronomers are curious about those deep craters. Maybe this fluffy moon, they posit, absorbs the impact objects more deeply. It also attracts dark material from Phoebe, several hundred thousand miles away. Hmm. I’m skeptical about it. Isn’t it easier to posit the dark material is part of Hyperion itself? Why invent inter-satellite migration of dark material on this scale?
As I see earthbound snowbanks melt, especially at the grocery store, I see deep “impacts” there, too. Not really impacts, but the dark grit melting deep into the ice and snow and leaving spiky frozen structures pointing at the southern sun.
Here’s another comparison. From the second floor window of nearby St Peter & Paul rectory (the site of our student retreat last weekend) I saw canteloupe-like terrain that reminded me of Triton, moon of Neptune. I couldn’t get a clear image from the second floor window, so I settled for this shot from the back porch:
That patch in the center outlined in red reminded me very much of Triton as imaged by Voyager 2 back in 1989:
Compare the Triton formation near the top of this image, where the angle of view is about the same as the backyard of the St P&P house.
Astronomers have seen much impact-driven geology in the solar system. More recently, we’ve seen resurfacing from volcanism on Io and geysers on Enceladus. I wonder, though, how much thought is being given to simple melting and geochemical processes.