March 11, 2018
Originally published October 14, 2008
image by Wes Higgins, Oklahoma
I made a discovery on this image of something that has been known for 30 years, and even was discovered by my colleagues. But this is a personal discovery and so this piece of information will remain with me longer than mere book learning. The discovery is of impact melt - do you see it? Look before you read further.
Wes' image of the 78 km diameter Fabricius (cut from his larger mosaic) highlights the very peculiar wall and floor of the crater. On the north, east and west sides of Fabricius the rim is high and massive rolls of slumped material are at the intersections of the rim and floor. The southern side has a low rim and little or no slumped material. It is just on the outer edge of the southern rim that I see a small pond of smooth material - the tell-tale sign of impact melt. Also on this image just at the wall shadow south of the central peak is a small piece of the floor rille that probably formed on impact melt. This Lunar Orbiter IV image shows the rille and less clearly, the pond. The Fabricius impact melt was catalogued in 1978 by B. Ray Hawke and Jim Head, working just down the hall from my office, but I don't remember that this was one of the impact melt craters they found. Oh well. Seeing this melt made me wonder how many of the impact melt craters Hawke and Head discovered have melt that is visible on telescopic (rather than orbital) images. Special Features, and we can see how many can be imaged.
09/18/08, 9:43 UT. 18" Reflector + Infinity 2-1m camera, MAP 80X64, stack of 212 frames.
Rükl plate 68
Hmm. I "discovered" this pond and rille a year ago on an earlier image by Wes....
Yesterday's LPOD: Beyond Red
Tomorrow's LPOD: Hemispherical Peak