January 13, 2021

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Sea of Dryness

Originally published June 26, 2011 lpod-Jun26-11.jpg
image by Giorgio Mengoli, Italy

The classical names for the lunar dark areas were all nautical, but all were dreadful misnomers since the Moon has always lacked seas and oceans. So today, we will examine the Sea of Dryness rather than Mare Humorum, the Sea of Moisture. Regional views, such as this superb image by Giorgio Mengoli, are invaluable for understanding an entire structural portion of the Moon. Many of the details visible here relate to the impact basin structure of the Humorum basin. The mare itself partially fills the basin depression with an estimated 3 km thickness of lava. The rim of the basin is most clearly visible in a partial arc running from SW of Gassendi south towards Liebig. Basinward of this arc is a scarp, reaching almost to Doppelmayer, that marks where the basin center dropped downward. Some of these fractures apparently allowed gas-rich magma to reach the surface making the dark-hued pyroclastic deposit and source rille west of Doppelmayer. The wrinkle ridges along the eastern edges of the mare mark an inner basin ring, and the famous rilles that cut Hippalus show where the weight of the mare lavas bent and fractured the edge terrain. And there are many more stories in this image, but we will wait for future LPODs!

Chuck Wood
This is a republication of an ancient LPOD from the second month of publication.

Technical Details
Takahashi cassegrain Mewlon 210 - 8" F/11.5 - 2415mm and HX516 ccd color 5300K.

Related Links
Rükl plate 52

Yesterday's LPOD: 1.5 Smythiis

Tomorrow's LPOD: Buried Crater Walls


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