Door 26 in the 2010 advent calendar
Posted by Emily Lakdawalla
26-12-2010 14:00 CST
Time to open the twenty-sixth door in the advent calendar. Until the New Year, I'll be opening a door onto a different landscape from somewhere in the solar system. Where in the solar system is this rayed crater?
This is Kamil crater in Egypt, which is notable for a couple of reasons: it was first noticed in Google Earth images (though "precovered" in satellite images dating back to 1972), and it has rays, which makes it very unusual among Earth craters. There are rayed craters elsewhere in the solar system, of course, but they're not at all common on Earth. Rays are the hallmark of a relatively fresh impact crater; older craters don't have them, as space weathering and other small-scale erosional processes wipe them away. On other worlds, "relatively fresh" can still mean "millions of years old." On Earth, though, with its active geology, rays don't last nearly that long; this crater is estimated to be fewer than 10,000 years old.
The Planetary Society Blog 2010 Advent Calendar