Home > Ephemeris Program, Observing, The Moon > Ephemeris: 09/12/2024 – Does the Moon have a square crater?

Ephemeris: 09/12/2024 – Does the Moon have a square crater?

September 12, 2024

This is Ephemeris for Thursday, September 12th. Today the Sun will be up for 12 hours and 39 minutes, setting at 7:58, and it will rise tomorrow at 7:19. The Moon, 1 day past first quarter, will set at 1:11 tomorrow morning.

I built my first telescope in the mid 1950s from the kit. It had a 5-inch diameter mirror. Of course one of the first things I looked at was the Moon. And while familiarizing myself with the Moon’s features I noticed that around first quarter moon there was a funny little crater near the Moon’s North Pole that looked square. All the other craters were round. This one being near the North Pole was foreshortened a bit, so it’ll look rectangular. It sure had walls that looked like they were straight rather than curved. The crater’s name is Barrow. And the description I found of it said it had an interesting shape, though they didn’t mention it was square. Looking closely at it, it is squarish but in small telescopes it definitely looks like it’s a square crater. The best time to try to spot it is around first quarter moon or up to a couple of days later.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.

Addendum

Barrow crater view on the Moon tonight
The northern half of the moon as it might be seen tonight this recreation using Virtual Moon Atlas. The crater Barrow is pointed out which under low power almost appears to be square.
Overhead view of Barrow crater
In this overhead view also from the Virtual Moon Atlas the Barrow crater appears rounder, however it seems to be about halfway between being round and square.

The base imagery used for the Virtual Moon Atlas, I believe, came from the Clementine spacecraft, a joint project of NASA and the Department of Defense, which orbited the Moon for 71 days in the mid 90s and then was sent out to an asteroid. However, on the way to the asteroid a problem occurred and Clementine was “lost and gone forever”.

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