November 24, 2006

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A Little Basin


image by Stefan Lammel, Uxbridge, England

A big crater or a little basin? Bailly is a famous large (303 km) feature on the Moon’s southwest limb that is readily seen when lighting and librations are favorable. But beyond identifying it, have you studied it? Bailly lacks a central peak, but does have a series of low hills that suggest an inner ring. In impact cratering, as the energy of impact increases beyond a level that creates craters 200-300 km wide, the central peak is transformed into a low scraggily ring of hills. Bailly is an example of the onset of such a peak-ring morphology of impact basins. Although they are fairly common on Mars and Mercury, there aren’t many peak-ring basins on the Moon. Bailly is also rather old - its rim and floor are littered with many later random (and Orientale secondary) impact craters. Bailly is a an old feature, but it is not a walled-plain, nor is it a just a big, battered old crater.

Chuck Wood

Technical Details:
November 5, 2006, 02:15UT. 10″ f4.8 Newtonian + DMK21-AF0 + Astronomik Red filter + 5x Powermate.

Related Links:
Rükl chart 71
An overhead view
Stefan’s website

Yesterday's LPOD: Happy Thanksgiving!

Tomorrow's LPOD: A Cloudy Night Read


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