The week of February 17-23 takes us from Lunar Day 20 to Day 26. This week we will highlight the moon craters Ptolemaeus, Alphonsus, and Arzachel, visible on Wednesday night near the terminator.
Ptolemaeus, Alphonsus, Arzachel: [SW/K-L9; L=3°W] (These may not be revealed until halfway through Day 7, or wait until tomorrow night.) This is the second group of favorite show-stopping trios on the Moon (the first being Theophilus, Cyrillus, and Catharina which you saw on Day 5). Both trios will richly reward close examination. Debris from the Imbrium impact has carved long valleys into the area immediately surrounding these craters. Examine the neighborhood when the terminator is close. (Don’t overlook the opportunity to revisit around Day 22 when the Sun is setting over these features.)
OF ADDITIONAL INTEREST IN SPACE
On February 18, 1930, Clyde Tombaugh discovers Pluto.
On February 19, 1473, Copernicus is born.
On February 17, 1600, the monk Giordano Bruno was burned at the stake in Rome for publicly stating that the Earth revolved around the Sun. He compounded his crime by suggesting that “Innumerable suns exist; innumerable earths revolve about these suns in a manner similar to the way the planets revolve around our sun. Living beings inhabit these worlds.”
======================
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
- Imposing Trio of Moon Craters - March 17, 2025
- Moon Craters Cleomedes and Proclus - March 10, 2025
- Posidonius and le Monnier – Two Moon Craters on Mare Serenitatis - March 3, 2025