Mysterious Lunar Swirls on the Moon May be Caused by Crashing Comets
http://www.scienceworldreport.com/articles/26216/20150602/mysterious-lunar-swirls-moon-caused-crashing-comets.htm
This is the first I have heard of this, but it seems it is an old ‘problem’. I guess the idea is since the comet has a huge ball of gas surrounding it that is moving at the same speed as the nucleus, when that cloud hammers into the moon (at the same speed as the nucleus, or 20-40,000 mph) it kicks up all sorts of dust the results of which can be seen from space as the color of the underlying dust is different.
