Archive

Posts Tagged ‘First quarter Moon’

Ephemeris: 02/24/2026 – Three cool craters at the Moon’s first quarter

February 24, 2026 Comments off

This is Ephemeris for Tuesday, February 24th. Today the Sun will be up for 10 hours and 55 minutes, setting at 6:23, and it will rise tomorrow at 7:27. The Moon, at first quarter today, will set at 3:33 tomorrow morning.

By the time we see the moon this evening it will be approximately half a day after became first quarter so it will be slightly gibbous tonight. Near the center of the moon near the terminator is a group of three craters . They are not a chain of craters in that they are of all of different ages. The largest in the north, called Ptolemaeus is named after Claudius Ptolemy the last great ancient Greek astronomer. The second is Alphonsus named after a Castilian king who was an astronomer. And the southern crater is Arzachel named after an 11th century Arabian astronomer and mathematician. In 1958 Soviet Astronomer Nikolai A. Kozyrev recorded the formation of a cloud near the center of the crater Alphonsus, suggesting perhaps some volcanic venting or activity.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.

Addendum

The telescopic first quarter Moon, featuring the three famous craters: Ptolemaeus, Alphonsus, and Arzachel. Moon image created using Stellarium.
Ranger spacecraft and closeup image of the Alphonsus crater.
Left: The Ranger spacecraft. Right: The floor of the crater Alphonsus from Ranger 9. Only the last 3 Ranger spacecraft were successful. They transmitted images all the way down as they crashed into the Moon. Credit NASA.
Categories: Ephemeris Program, Observing Tags: ,

Ephemeris: 03/06/2025 – The Moon at first quarter

March 6, 2025 Comments off

This is Ephemeris for Thursday, March 6th. Today the Sun will be up for 11 hours and 26 minutes, setting at 6:37, and it will rise tomorrow at 7:09. The Moon, at first quarter today, will set at 3:31 tomorrow morning.

The Moon is indeed at first quarter today with the instant of being 90° from the Sun coming at 11:32 this morning. To me the first quarter moon is the best time to view because there are a lot of craters that are visible in deep shadow. The terminator, the sunrise line, on the Moon cuts the disk in half and a lot of craters can even be seen in binoculars. With a small telescope the jumble of craters provides a wonderful view of the destruction of the early bombardment of the Moon in its early days. The reason the Moon has all these craters and the Earth does not is the fact that the Earth has an active surface with volcanoes, plate tectonics, water and wind to erode and deform the surface. The Moon has really none of that.

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

A look at the Moon tonight (March 6, 2025) 8 1/2 hours after first quarter at 8:00 PM looking at how the shadows change from near sunrise where the Sun is low and the shadows are long and as the Sun appears higher the terrain shows less in the way of shadows. Created using Stellarium, LibreOffice draw, and GIMP.
One of our moon balls that we use to illustrate the moon's phases and illuminated by a single light source shows near first quarter phase much like tonight's moon.
One of our moon balls that we use to illustrate the moon’s phases and illuminated by a single light source shows near first quarter phase much like tonight’s moon.
Categories: Ephemeris Program, Phases, The Moon Tags: