Archive for June 7, 2022

06/07/2022 – Ephemeris – The Moon’s Straight Wall

June 7, 2022 Comments off

This is Ephemeris for Tuesday, June 7th. Today the Sun will be up for 15 hours and 28 minutes, setting at 9:25, and it will rise tomorrow at 5:57. The Moon, at first quarter today, will set at 2:49 tomorrow morning.

Around the first quarter Moon there is, among all the circular formations on the Moon like craters, something that’s straight. Its name is Rupes Recta, better known as the Straight Wall. Tonight it’s a dark line seen near and parallel to the terminator, the sunrise line on the Moon, about a third of the way down from the center of the Moon’s disc to the edge. It looks like a cliff that’s 900 feet (300 meters) high and 67 miles (110 kilometers) long. It’s not. It is apparently a rectilinear fault, and its slope is only 7 degrees. It will disappear as the sun rises higher and illuminates the slope. It can be spotted in a small telescope, though it requires something generally larger and more powerful than a pair of binoculars. Near last quarter, the Straight Wall appears as a bright line.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.


Moon's Straight Wall locator

Moon’s Straight Wall locator, though it may not be visible at this magnification. Created using Virtual Moon Atlas.

Enlargement of the area of the Straight Wall

Enlargement of the area of the Straight Wall with labels blinking on and off. Created using Virtual Moon Atlas, Libreoffice, and GIMP.

Enlargement of the area of the Straight Wall near last quarter. Created using Virtual Moon Atlas.