September 22, 2009
Catching Some Zzz
image by Bob Pilz
Look carefully at the inner walls of Aristarchus. Notice anything unusual? Not the bright spot on the near rim which is where a ray was deposited. Look at the opposite rim where a terrace near the top of the rim bends sharply down and about halfway down the rim turns up and stops. The terrace directly below it repeats the Z shape. Terraces don't do this. They are places where a large, fairly coherent mass of rim material slides downslope as a unit. Often terraces can be traced halfway or sometimes nearly all the way around the rim, showing that the whole annular block slid down at the same time - what a sight! The Zs show up in Alan Friedman's shot has a high opposite lighting, clearly revealing the wall, but the Zs are not apparent. No better luck with Clementine, nor Apollo. Although it looks real I am beginning to think the Zs are a trick of lighting, rather than bending terraces. Who can come up with images to resolve this uncertainty?
2009/09/13, UT: ~10:47. 200mm f/6 Newtonian, Televue 4X Barlow, DMK 21BF04 camera, Blue filter, 15 fps, Exposure 1/30 sec, 800/18000 frames. Processed by Registax V5, PS CS4, FocusMagic. Taken from Lat: 35 degrees 36 minutes N, Long: 82 degrees 33 minutes W, Elev: ~850m.
Rükl plate 18
Yesterday's LPOD: Peas in a Pod
Tomorrow's LPOD: Crossing the Lines