The poles of Mercury and the Moon are among the coldest places in our solar system. If sufficiently cold, permanently shadowed regions (PSRs) near the poles of Mercury and the Moon may cold-trap and preserve volatiles such as water-ice for billions of years, but their origins and distribution are poorly constrained. Also, several recent studies indicated that thick ice deposits have been detected on Mercury, but not on the Moon, despite their similar thermal environments. To gain insights into this puzzle, a new study compared the morphology of thousands of simple, shallow craters at the poles of these two planetary bodies.
The results indicate that shallow craters near the South Pole of the Moon tend to be located in areas where surface ice was previously detected, similar to the poleward shallowing trend observed with the craters on Mercury containing thick water ice deposits. Additionally, a lack of this correlation near the North Pole of the Moon, i.e., absence of a morphological trend mirroring the one in the South Pole, is observed that is puzzling and poorly understood. READ MORE