Starship Asterisk*

BMAONE23 wrote:Given this image I would say it likely that the impactor either disintegrated upon impact and left the two light toned streamers from Messier A toward the left or grazed in both locations and bounded farther away. (most likely disintegrated upon impact)

bystander wrote:

BMAONE23 wrote:Given this image I would say it likely that the impactor either disintegrated upon impact and left the two light toned streamers from Messier A toward the left or grazed in both locations and bounded farther away. (most likely disintegrated upon impact)

Personally, I think it was two separate impactors. Regardless, there is a third option. The impactor(s) could be buried in the crater(s). But I agree with BMAONE23, most likely disintegrated.

BMAONE23 wrote:I agree that the two craters appear to have been hit at separate angles of attack. Messier is a glancing hit while Messier A is more a directly hit circular crater, though Messier A also shows an artifact of an earlier glancing blow. I would think that the impactor that created Messier gave a slight additional glance off at Messier A loc and was followed by a second impactor that created the more circular Messier A feature

Surprisingly, not much changes until the impact angle is less than 45° (measured from horizontal). But at shallower angles the crater becomes increasingly elongated in the direction of motion, and portions of the projectile ricochet and gouge out a series of small pits downrange from the main crater. As the impact angle changes, the ejecta and rays undergo even more pronounced changes than the craters do. When the impact angle is less than 15°, the ejecta pattern becomes elongated in the downrange direction and a "forbidden zone," where no ejecta appears, develops in the uprange direction. For grazing impacts of just a few degrees, the rays go sideways only, producing a butterfly-wing pattern. Amazingly, examples of all of these exotic ejecta patterns can be found on the Moon, Mars, and Venus.
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The really remarkable fact about Messier and Messier A is that the scientists Gault and Wedekind were able to beautifully mimic every one of the pair's weird features in laboratory impact experiments. A grazing impact (1° to 5°) of a projectile coming from the east excavated Messier (explaining its elongated shape and classic butterfly-wing ejecta pattern) and another part of the projectile ricocheted downrange to form Messier A and its long rays. Bigger craters formed obliquely too — look closely at Proclus, Kepler, Tycho, and even Mare Crisium. Maybe, on the Moon at least, truth really is stranger than fiction.