The week of December 15-21 takes us from Day 26 to Day 2. This week we will highlight the moon crater Bailly, visible on Tuesday night close to the terminator.
Bailly: [SW/R3; L=69°W] To observe this moon crater, it is best to wait for a favorable libration. It is a pity that Bailly lies so close to the western limb. It is the largest moon crater on our side of the Moon, and at just under 200 miles, it should qualify as a basin. It has ridges, internal crates, and a hint of some multi-ring features. close to the western limb. It is the largest moon crater on our side of the Moon, and at just under 200 miles it should qualify as a basin. It has ridges, internal craters, and a hint of some multi-ring features. Because its floor has not been flooded by lava, it retains much of the original detail from the moment of its creation. At over three billion years of age, it’s a bit tired and worn down, but worth visiting.
OF ADDITIONAL INTEREST IN SPACE
On December 15, 1970, a Russian spacecraft was the first to land on another planet (Venus).
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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
- Moon Crater Cassini – Created on Imbrium floor Before Lavas Started to Flow - January 19, 2026
- Bailly – Largest Crater on Our Side of the Moon - January 12, 2026
- Longomontanus: Exception to the Rule About Moon Crater Age - January 5, 2026