The week of July 6 to July 12 takes us from Day 22 to Day 28.
This week we will highlight the moon crater Longomontanus, visible on Tuesday 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 crater.
OF ADDITIONAL INTEREST IN SPACE
On Friday, the Pleiades are 1° south of the Moon.
======================
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 Clavius – Small Notch Chiseled Out of the Terminator - July 20, 2026
- Moon Crater Janssen – Larger Diameter than Copernicus - July 13, 2026
- Longomontanus – Exception to the Rule about Moon Craters - July 6, 2026