The week of January 9 to January 15 takes us from Lunar Day 17 to Day 22. This week we will highlight the moon crater Proclus, near Mare Crisium.

Mare Crisium on the moonProclus crater on the moonProclus: [NE/H14; L=47°E] Proclus is a small moon crater located just west of Mare Crisium. In spite of its size, it is one of the brightest spots on the Moon. When you view it around full Moon you will notice it also has a system of rays that delicately fan out in a telltale butterfly-wing pattern, which tells you a lot about the flight path of the incoming projectile. Proclus is one of the best examples of what happens during a low-angle impact. (See ejecta and butterfly patterns in the Glossary.)


On January 11, 1787, William Herschel discovers two moons of Uranus, and on January 14, 2005, Huygens lands on Titan.


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 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

Andrew Planck
Moon Crater Proclus: One of the Brightest Spots on the Moon
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