Birt (17 km), is a small crater, as the length of it's name by the way, located left of the Rupes Recta wall. This as shown, is a circular, cone-shaped crater. South East, superimposed on the edge, is even a smaller crater, called Birt A (7 km). Birt's floor is very small, if you imagine a cone (the floor is not visible in images because it is in the dark). At the northwest of the crater, is Rima Birt, a "ditch" that starts at one end with the crater Birt F (3 km), and ends at the other end with Birt E (5 km).
Rupes Recta in these images, is very distinct, because the Moon phase at that time, that makes this wall very clear. Observed overall, it gives the impression that there are two tectonic plates, and one yielded and became lower than the right one. Rupes Recta resembles as a fencing sword, especially in these lighting conditions.
This area seen in photo, is rich in features. It is an area that shows craters mountain regions and "Rupes". The Moon, has regions that have to be careful observed if you want to analyze it. What I find interesting here, is the "hidden" region of Nubium basin. This is a possible large crater in size, bigger even than the crater Ptolemaeus (Ptolemy), and which it fits even craters like Thebit (57 km), Birt (17 km), and Rupes Recta. I do not know if it was discussed about the possibility that in this area to be a hidden crater underneath Mare Nubium, but as shown by relief features, they fit with my hunch. In the picture below, notice what area it is. The eastern rim of the fictional crater, is high, mountainous, and on it is located the crater Thebit. In contrast to the wall, to the west there is a higher chain, which seems to continue the circle, giving the suspect, that this is a huge crater, which would have a size of approx. 200 km.
Moon age: 7 days
Phase: 51% (0% = New, 100% = Full)
Distance: 384.488 km
Optics: Celestron C8-Newtonian telescope, 20mm Plössl, 2x barlow
Mount: CG5 (EQ5)
Camera: Sony CX130
Location: Baia Mare, Romania
Processing: video capture, FastStone Image Viewer
Photo above is made in April 13, 2011.
LinkedIn comments for this article:
Kevin Read (FRAS) •I have always assumed that the crater outlined by you was a crater because it seems so obvious. As for the crack I believe that this is a fault caused by the shrinkage of the Moon as it gets colder. There are many shrinkage features in the form of anticlines in some of the larger craters known as 'wrinkle ridges'.