March 25, 2005
Can You Names These Craters?
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Image Credit: Paolo R. Lazzarotti |
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Can You Names These Craters? You know the Moon. You have observed it for years, and perhaps imaged nearly every part. So which craters are these? Probably only 1-2 percent of the nearly 2000 daily visitors to LPOD can identify the three large ones (from left to right) as Pitiscus, Vlacq and Rosenberger, near the southeastern limb. But if you dont know these craters you should be excited, for here is yet another corner of the Moon awaiting your personal exploration. What can you say about this region and these craters? Start with the terrain between the craters it is full of low ridges and small older craters that are nearly invisible. All three of the named craters are old enough that they show no ejecta on top of the intercrater plains. The terraces on their inner walls are virtually gone, and only relatively small central peaks rise above their floors. All three floors are flat, but there is a definite age progression as seen by the number of superposed craters on their floors. Rosenberger (diameter 96 km) has 15 easily counted floor craters, Vlacq (89 km) has about 10, and Pitiscus (82 km) has 4 or 5. All of these floors are less rugged than the intercrater plains. So a simple scenario (neglecting all the other craters) is that the big three formed on an existing plain. Some process covered the plain, including the craters on it and their ejecta deposits, with much small-scale roughness. Later smooth plains materials formed on the floors of Rosenberger, Vlacq and Pitiscus, in that sequence. Later smaller impacts cratered these floors. The ridges and roughness are probably ejecta from various impact basins, although the region is far from most basins. The smooth crater material seems to have been deposited at three different times and so could not all be the same age as necessary if they were ejecta from a recent basin-forming event such as Orientale. Modern lunar science does not accept that these smooth floors might be some sort of non-mare type volcanic deposits, but I cant explain them otherwise. The lack of volcanic features such as mare ridges, rilles or domes on such highland smooth plains suggests that is they are volcanic is a different style than mare volcanism. Technical Details: Related Links: Yesterday's LPOD: Floods and Buckshot Tomorrow's LPOD: A Long Crater |
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