April 6, 2010
Flat Out of Luck
image by Tiziano Olivetti, Italy
LPOD has featured so many great images of Eratosthenes that I have nothing new to say, but Tiziano's image is too grand to pass up. Although the radiating ejecta and secondary craters on the mare floor are impressive, what catches my eye are the flat spots on the crater's floor. Is it impact melt? I would think not since melt is only preserved so long and Eratosthenes is perhaps twice as old as Copernicus. The way to tell is to check with higher resolution images. A Lunar Orbiter V frame shows that the apparently flat areas are not really fllat, but they are darker than the rest of the floor. So far, there doesn't seem to be a hyper-resolution LRO image of the flat spots. So lacking definitive evidence it is still possible to wildly speculate: the flattish, dark area is impact melt that has been eroded, broken and nearly lost all of its pristine character.
See image bottom
Rükl plate 21