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

Andrew Planck

Author and Astronomer Andrew Planck shepherds you to the moon and its mysteries of intrigue and surprise. Learn about the moon’s most fascinating objects, understand how the moon was formed and the names of many of the craters … and why they honor individuals who have changed the course of history.
Andrew Planck
Lunar Basin Grimaldi and Lunar Transient Phenomena

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