Bob Moler's Ephemeris Blog

This is Ephemeris for Monday, March 10th. Today the Sun will be up for 11 hours and 39 minutes, setting at 7:42, and it will rise tomorrow at 8:01. The Moon, 4 days before full, will set at 7:11 tomorrow morning.

The moon tonight is bright. The sunrise line or terminator on the moon is crossing the large gray plain called Oceanus Procellarum, the largest of the moon’s seas. These seas were figments of the first telescopic observer’s imagination. They are really huge impact basins into which interior lava flowed. On the left edge of the Moon, just below center, this evening, at the terminator is a small shadow filled crater that might be visible in binoculars, but definitely telescopes. It’s called Aristarchus. It is a fairly new crater, probably less than a billion years old. As a rule the brighter the crater the newer it is. Aristarchus is the brightest spot on the Moon, when it is full. Visual astronomers have seen hazes and bright spots on rare occasions in and near Aristarchus.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.

Addendum

Aristarchus tonight, March 10, 2025, on the terminator (left), and Friday night, the 14th, before the total lunar eclipse starts. The enlargements show the telescopic view. Created using Stellarium, LibreOffice Draw and GIMP. The Moon doesn’t actually appear larger on the 14th. Apparently my field of view changed while getting the 14th’s image.