While not a visual observer, I thought I would try posting a bit more in the Lunar Observing forum because of my focus on imaging the moon.
Earlier this year I caught some good imaging and lighting around Mare Humorum. I find the rilles of Rimae Hippalus one of my favorite features in the area and find their concentric nature intriguing. The three main rilles are fairly easy to observe, but the fourth rille is more difficult to observe but the lighting in the attached image show this fourth rille fairly well. I do presume they were created by the impact that made Mare Humorum which is lava filled.
Edited by aeroman4907, 12 August 2019 - 07:12 PM.