1st quarter moon is December 3-4

The moon reaches its 1st phase on December 4, 2019, at 06:58 UTC. If you’re in the Americas, you can look for it on the evening of December 3. As viewed from the whole Earth, a 1st quarter moon is high up at sunset, looking like half a pie.

A precisely half-illuminated moon with a dotted line dividing the halves.

View at EarthSky Community Photos. | Our friend Dr Ski in the Philippines caught this photo as night came to his part of the world on November 4, 2019. He wrote: “The moon has reached 1st quarter and is visible on my side of the planet now.”

A first quarter moon rises around noon and sets around midnight. You’ll likely spot it in late afternoon or early evening, high up in the sky. At this moon phase, the moon is showing us precisely half of its lighted half. Or you might say that – at first quarter moon – we’re seeing half the moon’s day side.

We call this moon a quarter and not a half because it is one quarter of the way around in its orbit of Earth, as measured from one new moon to the next. Also, although a first quarter moon appears half-lit to us, the illuminated portion we see of a first quarter moon truly is just a quarter. We’re now seeing half the moon’s day side, that is. Another lighted quarter of the moon shines just as brightly in the direction opposite Earth!

And what about the term half moon? That’s a beloved term, but not an official one.

Read more: December 3-4 brings farthest 1st quarter moon

Read more: 4 keys to understanding moon phases

The lunar calendars are here! Get your 2020 lunar calendars today. They make great gifts. Going fast.

Half of the moon with Lunar V, Albategnius, and Lunar X labeled along straight edge.

Lunar X and Lunar V appear when the moon is near its 1st quarter phase. They aren’t really Xs and Vs on the moon. They’re just high areas, catching sunlight, creating an example of pareidolia on the moon. Aqilla Othman in Port Dickson, Negeri Sembilan, Malaysia, caught them both in May of 2017. Notice that he caught Lunar X and Lunar V.

Closeup of boundary between light and dark areas of the moon with Lunar V and X labeled.

Here’s a closer look at Lunar X and Lunar V. Photo by Izaty Liyana in Port Dickson, Negeri Sembilan, Malaysia. What is Lunar X?

Telescopic closeup of band of mountains on moon with a few large craters.

Tom Wildoner wrote: “One of my favorite areas to photograph on the moon near the 1st quarter! I captured this view of the sun lighting up the mountain range called Montes Apenninus. The moon was casting a nice shadow on the back side of the mountains. This mountain range is about 370 miles (600 km) long with some of the peaks rising as high as 3.1 miles (5 km).”

Bottom line: The moon reaches its 1st phase on December 4, 2019, at 06:58 UTC. If you’re in the Americas, you should look for it on the evening of December 3. As viewed from the whole Earth, a 1st quarter moon is high up at sunset, looking like half a pie.

Check out EarthSky’s guide to the bright planets.

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Deborah Byrd