lunar basin GrimaldiThe week of June 7 – 13 takes us from Lunar Day 27 to Day 3. This week we will highlight the lunar basin Grimaldi, located near the western limb of the Moon. Grimaldi has a very dark floor and several LTP’s (Lunar Transient Phenomena) have been reported here, so be on the lookout. You might get lucky!

Grimaldi is a genuine basin on the moonGrimaldi: [SW/K3] In comparison to Aristarchus (Day 11), which is the brightest spot on the Moon, Grimaldi is the darkest. Sunrise & sunset over Grimaldi is quite a lovely sight. The rim around Grimaldi has been heavily eroded by subsequent impacts, but once the floor is illuminated you will see quite a number of small craters, mounds, spots, streaks, and wrinkle ridges. LTP’s have also been spotted in the region, and some observers have reported being able to see a St. Andrew’s Cross emblazoned on the west wall. Grimaldi, in spite of its diameter of 143 miles, is a genuine basin, and if you look closely you might be able to trace out vestiges of an external ring.


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
Lunar Basin Grimaldi and Lunar Transient Phenomena

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