March 1, 2012
Back To the Pole
image by Raffaele Barzacchi
|Recently LPOD looked at a pathway from Mare Frigoris to the lunar North Pole. Now Raffaele has provided a closeup view of what you'll see as you approach the pole. Two craters, Anaxagoras and Scoresby, are relatively fresh, but all the rest are older and heavily affected by ejecta from the formation of the Imbrium Basin. One thing that I hadn't noticed before is the ridge to the left of Challis and Main. This is like a mare ridge, except there are no mare lavas here. The material filling the area west of Main and Challis is Imbrium ejecta. It is like lava in the sense that it may have been warm when deposited, and was also presumably not well consolidated. As it cooled and settled it probably became more compact. So it could have draped itself over an existing ridge, but it isn't curved as it would be if following an older crater rim. And it probably isn't a ridge formed as subsidence into a smaller volume, as circular ridges inside basins form. So why is this ridge here?
Yesterday's LPOD: Leaping Projectile
Tomorrow's LPOD: Magnificent Maginus