The week of October 26 – November 1st takes us from Lunar Day 10 to Day 16. This week we will highlight the crater Philolaus, viewable on Tuesday evening (Day 11).

moon crater PhilolausPhilolaus is a lunar impact crater that is located in the northern part of the Moon’s near side. It has a very rugged interior with two prominent mountain peaks. It lies within one crater diameter to the east-southeast of the flooded crater Anaximenes, and to the west of the smaller Anaxagoras. It overlies the older and heavily worn Philolaus C to the south.

moon crater Philolaus lies within one crater diameter to the east-southeast of the flooded crater AnaximenesDiameter: 43 mi.
Depth: 2 mi.


October 31st is a “Blue Moon” (the second full moon in a month). Blue Moons happen about once every two or three years, hence the phrase “Once in a blue moon” means a comparatively rare event.


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
Philolaus: Lunar Impact Crater

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