The week of August 3 – August 9 takes us from Day 21 to Day 26. This week we will highlight the moon crater Longomontanus, visible on Thursday night close to the terminator.
Longomontanus: [SW/P7; L=22°W] Take a look at Longomontanus and before reading further, decide if something seems slightly “wrong” about the moon crater.
Longomontanus is an exception to the rule that moon crater age can be determined by their relative sizes. Larger moon craters are almost always older, and when there’s an overlap, smaller moon craters will intrude upon the rims and floors of their larger and older cousins. The east rim of Longo has superimposed itself on top of what is obviously an older but smaller moon crater.
OF ADDITIONAL INTEREST IN SPACE
On Friday, the Pleiades are 1° south of the Moon.
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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
- Schrödinger – Large Impact Moon Crater Called a Walled Plain - August 10, 2026
- Longomontanus: Moon Crater Age Not Always Determined by Relative Size - August 3, 2026
- A Hint of Some Multi-Ring Features – Moon Crater Bailly - July 27, 2026