January 2, 2011
Daggers And Inverse Daggers
image by " rel="nofollow Jocelyn Sérot, France
The Moon's surface is simply ups and downs, with the juxtaposition between each creating topography. The variation in the elevation and azimuth of illumination yields a constantly changing pattern of shadows. Here Jocelyn has caught daggers of light and shadow that tell us about local ups and downs. A broad blade of shadow cuts across the floor of Walther (bottom center), being projected by its pit-topped central peak. " rel="nofollow Except the peak isn't centered in the crater, and the summit pit is less real than it looks (but the smaller pit lower down the peak is real). A negative dagger - a widening blade of light - illuminates a swath of the southern floor of Purbach (upper left). Topography is deceiving, for there is little indication that Purbach has a low spot in its southeastern rim, but the magnification of a long shadow reveals there must be. Look back down at the western rim of Walther to see a blunter dagger of light. In this case a broad section of the rim is low so that the there isn't a V-shaped illuminated area, but one that looks like a slice of pie that someone - not me - has eaten the tip of.
" rel="nofollow Chuck Wood
Technical Details
Dec 13, 2010, 19h36 UT. 6" MCT @ F/D=24 (Barlow), Red filter, DMK 31 camera; Processing: Avistack 2 + Registax 5
Related Links
Rükl plate 65
