moon crater PytheasThe week of December 4-10 takes us from Day 22 to Day 27. This week we will highlight the moon crater Pytheas with its secondary craters, viewable on Tuesday after midnight.

Pytheas secondary moon craters: [NW/G7-8; L=19°W] The best place to see secondary moon craters that have landed within a splash ray is just 25 miles east of Pytheas. There is an alignment of seven or more secondary craters that are obviously confined within a long ray extending from Copernicus, 160 miles to the south. Tonight it is difficult to observe the connection with Copernicus because the craters are visible on Day 9, but the ray can be more clearly seen later at higher sun angles. So draw the alignment of craters tonight, then come back closer to full Moon and fill in the splash ray.


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 Pytheas with its Secondary Craters

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