June 26, 2004

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An Older Copernicus



Image Credit: Craig Zerbe

An Older Copernicus

Copernicus is the exemplar of a large complex crater. There are a few dozen other relatively fresh Copernicus-like craters on the lunar nearside - and a significant, but often overlooked one lurks just a few hundred kilometers to the east. Eratosthenes is a junior Copernicus - 58 km diameter vs 93 km - and is somewhat older. As Craig's excellent image details, Eratosthenes has wonderfully preserved terraces and massive central peaks, and an extensive array of secondary craters that have excavated radial crater chains into Mare Imbrium lavas. If you look at this area near full Moon you will see that Eratosthenes disappears, while Copernicus is very bright, and a Copernicus ray crosses Eratosthenes. Also, look carefully at full, and see if you can detect the short remaining ray from Eratosthenes that extends to the north. Copernicus is clearly younger than Eratsothenes, and that crater, obviously, is older than the nearby maria and the Apennine Mountain spur the crater excavated into. Mouseover for another excellent view, this one from Apollo 17 (AS17-145-22285), looking south, and just catching a profile of Copernicus on the top left.

Chuck Wood

Technical Details:
Celestron 11 inch SCT mounted on a Losmandy G11, using an Astrovid 2000 camera. The image results from stacking 200 semi-frames.

Related Links:
Craig's Lunar Images

Yesterday's LPOD: Cassini Observed

Tomorrow's LPOD: An Older Tycho

Author & Editor:
Charles A. Wood



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