More Mercury awesomeness from MESSENGER:
Wow, this one is very high res (click to embiggen)!
It was taken when MESSENGER was less than 6000 km over the surface, and shows crushing detail near Mercury's equator (the smallest things you can see are about 300 meters across, roughly as detailed as you get looking at the Moon through a big earthbound 'scope). The whole image is about 170 km across.
There are so many things to see! The huge crater at the lower right is interesting. I'm not sure what crater it is, or if it was even mapped by Mariner 10 back in '74; I'm still figuring out how to match up the maps. I'm guessing the crater us about 200 km across. We only see one quadrant of it here, but there's lots of stuff to note. The rim is incredible, seen in great relief due to the low sun angle.
The floor of the crater is relatively flat, so I suspect some later event filled it in, maybe volcanic flow. Then, over time, more asteroid impacts created the peppering of tiny craters all over it. But the floor is also cracked, which doesn't surprise me too much. Cracks like that are all over the tiny planet, possibly due to the crust shrinking as the planet's core cools and shrinks. That right there is fairly mind-boggling.
The linear radial features -- the lines coming straight out of the center all around the crater -- are probably secondary events, streamers of rocks that splashed out of the crater when the impactor hit. They slam back into the surface and create littler craters.
Heh. At the top is a biggish crater, and you can just see a little crater inside it, with its rim poking out into the sunlight.
Now, I'm not geologist, I'm just a country astronomer, but if I can see this stuff at a glance, I'm guessing people like Emily are having braingasms right now. And this is just one of three high-res images they just downloaded! I'd love to be at the data center at APL right now.
Fun fun fun. And more to come!