The week of April 6-12 takes us from Lunar Day 13 to Day 20. This week we will highlight the Serpentine Ridge viewable on Saturday evening.
Serpentine Ridge1: [NE/G12] West of the crater Posidonius in the Sea of Serenity you will find the Moon’s best example of a wrinkle ridge. Like breaking waves that sometimes indicate reefs lying just under the surface of the water, wrinkle ridges often signal the presence of subsurface structures on the Moon. Serpentine Ridge reveals the ghostly outlines of an underlying mountain range that formed the inner ring of the Serenity basin. At the highest point of this ridge, just west of Posidonius where it looks like the ridge splits into a “Y,” 
there is a tiny 1.2-mi. crater that will test both your optics and the seeing conditions.
OF ADDITIONAL INTEREST IN SPACE:
On April 12, 1961, Soviet cosmonaut Yuri Gagarin becomes the first man to orbit the Earth.
1 “Serpentine Ridge” is the picturesque name that amateur astronomers have been using for this feature since the 1800’s. However, in 1976 the International Astronomical Union officially changed the name to “Dorsa Smirnov” (which is a good example of why scientists don’t make good poets).
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It is highly recommended that you get a copy of Sky and Telescope’s Field Map of the Moon, the very finest Moon map available for use at the telescope. It is available for $10.95 at www.skyandtelescope.com and on Amazon. All features mentioned in this blog will be keyed to the grid on the Field Map and will look like this: Plato: [NW/D9]
Credits:
Courtesy of Gray Photography of Corpus Christi, Texas
Lunar photos: NASA / USGS / BMDO / LROC / ASU / DLR / LOLA / Moon Globe. Used by permission
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