02/19/2021 – Ephemeris – Let’s look at the first quarter Moon tonight

This is Ephemeris for Friday, February 19th. Today the Sun will be up for 10 hours and 40 minutes, setting at 6:17, and it will rise tomorrow at 7:34. The Moon, at first quarter today, will set at 2:32 tomorrow morning.

I love a first quarter Moon. The terminator or sunrise line cuts the Moon in half. Lots of craters are easily seen due to the long shadows cast by their crater walls. Best seen in a small telescope or strong pair of binoculars is a three crater chain just below left of the center of the Moon. The top and largest crater is Ptolemaeus. Below and connected to it is Alphonsus. A bit below Alphonsus is Arzachel. Alphonsus is the interesting one. In the pre-Apollo days amateur and some professional astronomers saw glows or mists in Alphonsus. In 1958 a Russian astronomer obtained spectra of one such mist. In 1965 the last Ranger mission to impact the Moon was sent to Alphonsus, but it didn’t find anything unusual.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The first quarter Moon tonight at 8 pm, February 19, 2021, as it might be seen in binoculars. Created using Stellarium.

A telescopic like view of the Moon via the Virtual Moon Atlas pointing out the craters discussed in the text.

Ranger 9 Image of Alphonsus #1. Credit NASA/JPL.

Left: The Ranger spacecraft. Right: The floor of the crater Alphonsus form Ranger 9. Only the last 3 spacecraft were successful. They transmitted images all the way down as they crashed into the Moon. Credit NASA/JPL.