In Mr. Hill’s classic A Portfolio of Lunar Drawings he sketched Lacus Mortis (Lake of Death) near complete sunset. He comments that long shadows from the western peaks grow with changing direction, presumably due to the local topography. Yet, to him it seemed there was nothing visible to effect those strong directional changes. He encouraged continued study of the area in the interest of understanding the complex floor of Lacus Mortis. Remember, this was in the mid 1980’s long before we had the very high detail imagery available today.
As a result of reading his discussion I added Lacus Mortis to my list of special points of interest. One early morning October 7, 2020 I took afocal video through my f/10 8” SCT and 9mm eyepiece. 25% of roughly 1000 frames were stacked with Autostakkert3. Unsharp masking and final processing were made with PSE. My images are displayed with south north at the bottom to match Hill’s presentation. Although dark due to the low sun I see the “bending” of shadows as they approach crater Burg to the east.
I don’t have a full understanding of this “phenomenon” but suspect the apparent bending is a result of two intersecting shadows. I made a sunset animation using NASA’s SVS Dial-A-Moon, but the hourly increments are too coarse for the rapidly changing view.
James
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Edited by Proton Flipper, 07 February 2021 - 09:57 AM.
