Geological Chronicle
Located in Mare Fecunditatis, Messier is an oblong impact crater measuring 13.8 kilometers in diameter. The feature's elongation is not caused by foreshortening, and its longer dimension is oriented east–west.
Immediately to the west lies Messier A, an oblong doublet crater oriented north–south at right angles to Messier. Scientists theorize that Messier formed during a very low-angle impact, with Messier A potentially forming from a rebound of the projectile. Both crater interiors display a higher albedo than the surrounding mare, marked by dark central streaks.
The oblique impact trajectory also accounts for an asymmetrical ejecta pattern, including two prominent rays extending over 100 kilometers westward from Messier A toward the edge of Mare Fecunditatis. To the northwest of Messier A lies the narrow rille Rima Messier, while NASA's Lunar Orbiter 5 spacecraft photographed the crater pair at high resolution in August 1967.