New Views of Diverse Worlds
by David T. Blewett
|False-color image of Mercury. Courtesy NASA / Johns Hopkins University Applied Physics Laboratory.|
A lot of strange sights have been seen on Mercury, things that the MESSENGER team is still trying to understand. For instance, the images reveal certain craters that have dark rims; several are found within the Caloris basin. This rather surprising. The dark rim indicates that the impact dug up dark material from beneath the surrounding smooth plains, which have a higher albedo.
Another class of crater on Mercury has highly unusual bright stuff on their floors. Mariner 10 spotted a number of them, though at fairly poor spatial resolution, and few scientists at the time really thought much about the bright material. But now we've seen many more with MESSENGER — I'll have more to say about them later on, but they're turning out to be amazing.
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