A crater chain inside a large lunar crater, some 200 miles (300km) southwest of Tsiolkovsky crater. Most crater chains form from streams of ejected blocky debris thrown out during a crater impact that fall back onto the lunar surface some distance from the original crater. Ejected debris striking the ground at a shallow angle produces elongated craters. Individual craters in a chain may sometimes overlap as is seen in this photo. (Apollo 15 Metric camera stereo photo AS15-M3-1856 & 1857, orbit 50)