As part of a wealth of new information presented today by the MESSENGER science team, this image shows the interior of Sander Crater, located within Mercury’s vast Caloris Basin. Areas seen as bright spots in previous lower-resolution images have been revisited by MESSENGER once it entered orbit and began its science mission. The bright areas turned out to be unexpected landforms named “hollows”, clustered irregularly-shaped depressions with bright interiors and halos. Hollows have since been found in many areas across Mercury, although the exact process that creates them is not exactly known. They may be the result of the erosion of volatile material by solar wind.
The lack of craters within the hollow clusters seems to indicate that they are relatively young features.
“Analysis of the images and estimates of the rate at which the hollows may be growing led to the conclusion that they could be actively forming today,” says David Blewett, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL). “The old conventional wisdom was that ‘Mercury is just like the Moon.’ But from its vantage point in orbit, MESSENGER is showing us that Mercury is radically different from the Moon in just about every way we can measure.”
Seems that MESSENGER’s first six months around Mercury have been very productive ones! It will be interesting to see what else it will discover as the only spacecraft ever to orbit the first rock from the sun.
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