The week of July 26 – August 1 takes us from Lunar Day 18 to Day 23.

Moon craters Peirce & PicardThis week we will highlight the moon craters Peirce and Picard, viewable early Tuesday morning.

Mare Crisium on the moon showing Peirce and PicardPeirce & Picard: [NE/H15] The two largest intact craters on Mare Crisium are Peirce and Picard. They are only about 12 miles in diameter by 1 mile deep and will require 75x – 100x to see them. They are located on a more-or-less north-south line about 30 miles in from the western shore of Crisium (Peirce is the northernmost). The lava that covered Crisium stopped flowing before these craters formed. You should easily be able to spot Swift, a small seven-mile crater just eight miles to the north of Peirce.


The Delta Aquarid meteor shower peaks after midnight on Tuesday. Look toward the southeast.


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
The Two Largest Intact Moon Craters: Peirce and Picard

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