The week of December 6-12 takes us from Day 3 to Day 9. This week we will highlight Vallis Rheita, viewable on Tuesday & Wednesday evening, Days 4 and 5.
Vallis Rheita: [SE/N14; L=52°E] At 276 miles, the Rheita Valley is the longest distinct valley on the Moon. If you look closely at this formation, you will see that it is not a valley in the traditional sense but is made up of a series of interlocking craters whose alignment significantly points back to Mare Nectaris, their place of origin. When the Nectaris basin was blasted out 3.9 billion years ago, more than a dozen mountain-sized chunks of debris took flight in a curiously straight line, and when they landed they ploughed out a 240 mile-long trough which we enjoy observing today as the Rheita Valley.
Although the Moon usually appears absolutely flat, this sector of the Moon gives you a noticeable three-dimensional effect as Rheita Valley diminishes into the distance around the curve of the Moon1.
1 During a lunar eclipse you will frequently notice a striking three-dimensional effect as light being refracted through the atmosphere on opposites sides of the Earth strike the lunar surface from different angles.
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]
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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