https://www2.lpod.org/index.php?title=November_20,_2021&feed=atom&action=historyNovember 20, 2021 - Revision history2024-03-29T09:49:34ZRevision history for this page on the wikiMediaWiki 1.31.1https://www2.lpod.org/index.php?title=November_20,_2021&diff=46241&oldid=prevApi: Created page with "__NOTOC__ =Where They Are= Originally published January 6, 2012 <!-- Start of content --> <!-- ws:start:WikiTextHeadingRule:0:<h1> --> <!-- ws:start:WikiTextLocalIm..."2021-11-20T09:05:07Z<p>Created page with "__NOTOC__ =Where They Are= Originally published January 6, 2012 <!-- Start of content --> <!-- ws:start:WikiTextHeadingRule:0:<h1> --> <!-- ws:start:WikiTextLocalIm..."</p>
<p><b>New page</b></p><div>__NOTOC__<br />
=Where They Are=<br />
Originally published January 6, 2012<br />
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<em>image from [http://adsabs.harvard.edu/abs/2010E%26PSL.295..147W Stephanie Werner &amp; Sergei Medvedev (2010)]</em><br /><br />
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I like maps that show the distribution of different types of features on the Moon. This is a new one that plots ray craters, <br />
here shown 5 times their actual diameters for this scale map. There are 1707 rays craters with diameters as small as 500 <br />
m between 70° N and S - it is too difficult to detect rays closer to the poles. Most of the circles representing rayed craters <br />
are too small to see because only 273 have diameters of 5 km or larger. This is another demonstration of the power law <br />
distribution of crater diameters. We observe and get excited by the big craters, but they are a small minority of all craters. <br />
This study showed that rayed craters as a population are about 750 m.y. old, and that date should be recognized as the <br />
age of the boundary between young Copernican craters and older Eratosthenian ones. Currently, the boundary is said to be<br />
at 1.1 billion years, but that includes rays due to composition - bright anorthosites on dark maria - that age more slowly than<br />
rays whose brightness is due to the freshly pulverized rocks. Another discovery from this extensive mapping is that craters<br />
are concentrated in the direction of movement of the Moon in its orbit, but not as coherently as [http://www2.lpod.org/wiki/September_25,_2011 previously] believed. This <br />
work has produced a new list of rayed crater locations and diameters which can be the basis for a further study to add ray<br />
lengths and to devise a ray classification. <br />
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<em>[mailto:tychocrater@yahoo.com Chuck Wood]</em><br /><br />
<br /><br />
<strong>Technical Details</strong><br /><br />
I thank Stephanie for a copy of her paper and the rayed craters database.<br /><br />
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<p><b>Yesterday's LPOD:</b> [[November 19, 2021|Limb Magic]] </p><br />
<p><b>Tomorrow's LPOD:</b> [[November 21, 2021|A Long Line in a Clutter of Magnificence]] </p><br />
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