December 4, 2012
The Adams Family
Clementine image (left) from Map-A-Planet and LRO (right) from QuickMap
A strange one-sided ray on Howard Eskildsen's image of two days ago seemed worthy of further attention and it is.
As pointed out in yesterday's LPOD the broad ray extends from the bright-rimmed, flat-floored crater just west of
Adams. The crater is Adams B, which is unusual for its decidedly elliptical shape of 27 x 38 km; it is about 3 km
deep. The ray is as wide as B's long axis and extends perpendicular from it for about 150 km and then thin strands
continue that much further. I don't know of any other one-sided ray craters on the Moon. What immediately comes
to mind is a very low angle oblique impact with butterfly wing rays 90° from its elongated axis. That could be the
explanation except that there is no evidence for a ray to the south east. The closeup LRO image reveals a fresh
crater - as its bright rim indicated even from Earth - with a flat plateau on the right side of its floor. Zooming in on
this area on QuickMap shows the unit to be an coarse impact melt with large crenulations where it changes from
smooth-surfaced to a more rugged texture. While in QuickMap look at the ray-covered area to the northeast of B.
With the lower Sun of LRO the ray is not visible as an albedo feature but it corresponds to a topographically slightly
muted surface, as if veneered by a greater depth of material than in normal rays. Adams B is definitely a feature to
keep investigating. And while in the neighborhood note the faint rays around the central peak crater Palitzsch B at
top-center of the Clementine image. It looks like it could be an oblique impacr crater but at a higher angle for the
rays are quite visible on all sides except the southeast.
Chuck Wood
Related Links
Rükl plate 76
21st Century Atlas charts 5, L3 & B3.
