April 2, 2005
Purblind? No!
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Image Credit: Paolo R. Lazzarotti |
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Purblind? No! Purblind - lacking in vision, insight, or understanding. Merriam-Webster Online. Purbach -- a lunar crater which requires good vision to see all the details and understanding of geologic processes to interpret! Purbach is an 118 km diameter crater in the highlands east of the Straight Wall. Its high walls (nearly 3 km) have no remnants of their former terraces, and two peaks could be central peaks, but they also help define a circle. Lunar mappers interpreted this circle as an old and mostly buried crater and gave it the designation Purbach W. The light-hued flat floor of Purbach is peppered with small impact pits, many of which are probably secondary craters, some perhaps from Tycho. The interior of W has fewer crater pits than most of Purbachs floor. Similar less cratered patches occur just to the right of the peaks and also at the south edge of the crater near a massive wall remnant. These three less cratered patches are an enigma. If they are the same age as the rest of the smooth floor how did they escape impact pitting? They couldnt have, so we are left to conclude that they are younger. Lunar scientists do not accept that light smooth plains like this are volcanic but rather interpret them as fluidized ejecta from impact basins. But that explanation can not explain why these three spots are younger. I speculate that the smooth plains are an unsampled type of lunar volcanism; conventional lunar scientists would respond that the less cratered patches are statistically insignificant cratering isnt completely random and therefore there is no enigma to explain. Who is purblind? Technical Details: Related Links: Yesterday's LPOD: LPOD Image of the Month - March 2005 Tomorrow's LPOD: A Wondrous Image! |
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