At one time or another almost every lunar craters had been considered volcanic - but now almost all the craters can be convincingly re-interpreted as products of impact craters. Then there are craters on the moon? Yes, a few, and I long ago I published the photos (
http://www.astrobin.com/full/48970/0/?real=&mod= /
http://www.astrobin.com/full/98680/0/ ) that are perfectly visible in the dark halo craters Alphonsus floor. But first, as we know that they are not impact craters?
1. Because they are not circular.
2. They are surrounded by dark halos.
3. They occur along rilles.
The answers (1) and (2) can be explained by impact processes, but the response (3) is unlikely to result from impacts. Spectral studies also show that dark haloes are pyroclastic material (gray) and not fragmentation of rocks on the ground. Considering all these features together volcanism is the only reasonable interpretation.
In the early 1970s McGetchin Tom and Jim Head made a comparison of these craters to terrestrial cinder cones. On Earth, cinder cones, such as Sunset Crater in northern Arizona, are tall and have steep sides. Head and McGetchin realized less the Moon's gravity and lack of atmosphere, exactly the same eruption on the moon would produce a large crater and low much like with these beautiful dark halos Alphonsus.
Source: LPOD - Charles Wood
Adaptation: Avani Soares
Comments