Astronomy Essentials

International Observe the Moon Night October 21

International Observe the Moon Night 2023

International Observe the Moon Night (InOMN) is October 21, 2023. It’s a worldwide event for moon-lovers, held annually since 2010. It’s scheduled each northern fall, on a night when the moon is near the first quarter phase. In October 2023, the first quarter moon is October 21. So you’ll see a first quarter moon in the sky on Saturday evening.

Observing the moon with a telescope around quarter-moon phases is more fun, because more detail is visible on the line between lunar light and dark (day and night). That line is called the terminator. On a first quarter moon, that’s the line of sunrises, and just as during an earthly sunrise, shadows are longest along the lunar terminator. So lunar features stand out most clearly then. Also, look beyond the terminator for an illuminated mountain peak or crater rim that appears as a speck of light on the dark moon.

Click here to download NASA’s 2023 observe the moon map.

The 2024 EarthSky lunar calendars are here! Best Christmas gifts in the universe! Check ’em out here.

International Observe the Moon Night: Half illuminated moon at 1st quarter. At its illuminated side, there darker areas and many craters.
View at EarthSky Community Photos. | Mohamed Mohamed of Tripoli, Libya, captured this great image of the 1st quarter moon on January 28, 2023. Thank you, Mohamed! For you moon-watchers … a global, public event – International Observe the Moon Night – is October 21, 2023. Learn how to participate here.

Participating in International Observe the Moon Night

How can you participate? Will there be star parties with telescopes, or other events, in your area? Go to the InOMN website to find an event near you. There’s also information about how to host an InOMN event. And you can share pictures and highlights from your moon-watching fun on October 21.

Also, check out this Ten Ways to Observe the Moon.

Want to stay home and have fun observing the moon with your family? Try this article from NASA Night Sky Network: Weird ways to observe the moon

How to observe, safely

The InOMN website states:

Whether you are able to safely host a physical event or you are interested in planning a virtual event, we are here to help. Please observe in the way that is healthiest for your community and yourself …

Your event can be a small gathering of friends or family, an online program for thousands of visitors, or anything in between. The size, location, and agenda are for you to determine, based on public health guidance in your area, your interests and expertise, the interests and needs of your audience, and the resources you have available.

Though we encourage everyone to participate in International Observe the Moon Night on a specific date each year, we understand that this date may not work for everyone. You are welcome to host your event on a different day. The main objectives are for you and your audience to observe and learn about the moon as well as celebrate your personal and cultural connections to our nearest celestial neighbor.

Click here to register your event for International Observe the Moon Night

Go to the event’s website to look for an InOMN event near you

First quarter moon photos from our EarthSky Community

A slightly curved terminator line, on a moon just past 1st quarter. There are darker areas and crater on the illuminated side of its surface.
View at EarthSky Community Photos. | Cathy Adams in St. Stephen, New Brunswick, Canada, caught the first quarter moon on January 28, 2023. As a matter of fact, the moon is one of the best targets for binoculars. The terminator line, or line between light and dark on the moon, is the best place to aim your binoculars on the moon. See how you can glimpse sunlight on the rims of lunar craters along the terminator? Thank you, Cathy!
Almost quarter moon in blue sky with out-of-focus tree limbs in front.
View at EarthSky Community Photos. | Deirdre Horan of Dublin, Ireland, caught this image on June 25, 2023, and wrote: “The waxing crescent moon, nearing its first quarter.” Thank you, Deirdre! If you don’t want to stay up late, you can see the first quarter moon in the daytime. Look here for online events, and events near you, for International Observe the Moon Night 2023, on October 21.

Thank you to all who submit images to EarthSky Community Photos! View community photos here. We love you all. Submit your photos here.

Bottom line: A global, public event – International Observe the Moon Night – is October 21, 2023. You can look for events near you and to learn how to participate online.

October 20, 2023
Astronomy Essentials

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