here for larger NASA image
Click here for lunar chart showing location
Messier (1) and Messier A (2) are a pair of unusual craters in northwestern
Mare Fecunditatis. Messier is elliptical and has bright walls and light
rays of ejecta extending at right angles to its long axis (approximately
16.5 km). Messier A is a doublet crater having two very long rays or filaments
of ejecta extending westward from it. The east part of the doublet has
steep, bright walls, whereas the west part is dark and appears mantled.
Differences between the two parts are more clearly shown in this oblique
view of Messier A composed as a stereogram. Both Messier and Messier A
resemble some small experimental impact craters produced in sand by projectiles
following shallow trajectories (4° or less from the horizontal) at
velocities of approximately 1.7 km/s. In separate experiments using single
projectiles, both elliptical craters with lateral ejecta lobes and doublet
craters have been produced. Thus, it can be inferred that these lunar craters
were produced by high velocity projectiles following shallow trajectories.
By further analogy with the experiments, the projectiles that formed
Messier and Messier A apparently traveled from east to west.-H.J.M.
AS16-4471 (P) AS16-4469 (P)
Report Source: NASA SP-362, Page 121, Figure 115
This web page was created by Francis Ridge
for The Lunascan Project
Section Directory 48