May 10, 2014

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Bright Rim

image by Raffaele Barzacchi, Italy

Using a large telescope for an amateur (18"), Raf has acquired an image of the Theophilus area that compares favorably with the LRO Wide Angle Camera image of the same area. To make the comparison even more visually captivating, Raf added nomenclature from the Gazetteer of Planetary Nomenclature, using yellow font, just as QuickMap does. The image itself shows many interesting features. The now well-known impact melt ponds on the north flank of Theophilus show up as smooth, featureless areas. And the dark halo craters (of impact origin), such as Beaumont L are also nicely visible. What is more subtle is the change in brightness of the upper inner rim of Theophilus. Look along the top of the brightly illuminated (west) side of the crater and you can easily see that the upper part of the rim is brighter than the lower part. LRO high resolution images confirm what Raf has captured. A similar band of brightening has been noticed at other large craters. As proposed earlier, is the bright upper part, fragmental fallback ejecta that may contain anorthosite or is it bright simply because it is fragmental (as is ray material)?

Chuck Wood

Related Links
21st Century Atlas chart 7.

Yesterday's LPOD: Would You Like a Second Helping?

Tomorrow's LPOD: Globe History


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