December 1, 2020
Originally published May 14, 2011
image by Meg Rosenburg and colleagues (JGR and NASA)
Any complex map, like this one that shows slopes of terrains at different scales, takes some study to understand. Basically the three colors indicate roughness at different scales. Red areas are rough over distances of about a kilometer, green represents a few hundred meters, and blue is tens of meters. The the mare are generally smooth until small scales are considered - mare ridges and small crater rims typically have relief of 10s of meters. At the other end of the scale are Tycho, Copernicus and a few other very fresh craters with yellow-white interiors. These are rough at all scales from the high crater walls to cracks in the impact melt covered floors. Notice the less dark hues that surround Tycho and map out the continuous ejecta blanket. Now look at what circles the Orientale Basin. Some of the oddest craters are ones like Aristoteles, Langrenus and Compton that have yellow rims and bluish floors. Compton has lavas on its floor, but the other two have smoothness that may be due to impact melts.
Yesterday's LPOD: Little Hills and Little Illuminations
Tomorrow's LPOD: Little but Good