Moon in Gemini – near Castor and Pollux – November 21 and 22

Moon in Gemini: Two positions of moon on succeeding days with Castor, Pollux, and other labeled stars.
Look for the waning gibbous moon in your eastern sky in late evening on November 21 and 22, 2021. It’ll be near 2 stars that are bright and close together on the sky’s dome: Castor and Pollux, the Gemini “twins.”

Moon in Gemini

On November 21 and 22, 2021, before going to bed, look for the moon in your eastern sky. It’ll be a bright waning gibbous moon, less than perfectly round. And you might notice two bright stars in the moon’s vicinity. They are Castor and Pollux in the constellation Gemini. These stars are noticeable for being both bright and close together on the sky’s dome. That’s why – in legends of the sky – they often represent Twins.

From mid-northern latitudes, Castor and Pollux appear over your eastern horizon with the moon by around 9 p.m. on November 21. The next evening – on November 22 – Castor and Pollux will rise about four minutes earlier. The moon will come up about one hour later. On November 23 after 10 p.m., Castor and Pollux will form a straight line with the moon. From the Southern Hemisphere, they all ascend in the east a bit later in the evening, after 11 p.m. If you’re not one for staying up late, you can always get up before dawn to view the moon and Gemini stars in the morning sky. Then they’ll be in the west!

The moon’s glare will make it difficult to see the entire, faint starlit figure of the Twins for the next few nights. But Castor and Pollux are bright! You’ll be able to pick them out, even when the moon is passing in front of Gemini.

For a clearer view, look again for the twin stars after about November 24, when the moon has moved on in its orbit around Earth. As it does so, it’ll be waning, or appearing less bright each evening. And it’ll be rising later, in a part of the sky not so near Castor and Pollux.

Keep track of the moon’s phase for every day in 2022! EarthSky’s lunar calendars are available now. Guaranteed to sell out, so get one while you can.

November 22 moon near M35

Star chart of moon in star field with prominent star cluster below.
Observer’s challenge: The moon and the star cluster M35, also known as the Shoe-Buckle Cluster, come within 2 degrees of each other early in the morning (around 08:00 UTC) on November 22, 2021. Can you spot the cluster by the bright moon, or does it wash out the fainter stars? Let us know in the comments below, and if you grab an image, share it at EarthSky Community Photos! Image via Stellarium.

After the moon moves away

The constellation Orion the Hunter is just south of the moon on November 20. If you look for Orion, and come to recognize its stars, you’ll have another way of finding Castor and Pollux.

Orion is easy to see. It has many bright stars. You’ll always know you’re seeing Orion if you notice its Belt stars: three medium-bright stars in a short, straight row.

You can star-hop from Orion to Castor and Pollux. Simply draw an imaginary line from Orion’s Belt through the bright star Betelgeuse to find the Gemini stars Castor and Pollux. This way of finding Gemini’s two brightest stars works in both the Northern and Southern Hemispheres. See the chart below.

At mid-northern latitudes – like those in the mainland United States – the constellations Gemini and Orion rise at approximately the same time. However, at more northerly latitudes – like those in Alaska – Gemini rises before Orion. That far north, the Big Dipper is visible at early evening just above the northern horizon. So you can use the Big Dipper bowl to star-hop to Castor and Pollux. See the chart below.

By the way, the star Castor in the constellation Gemini very closely marks the radiant point for the Geminid meteor shower, which peaks every year around December 13 or 14.

Star chart of constellation Gemini with stars in black on white, purple arrow from Orion to Gemini.
When the moon is no longer in front of Gemini, you can use the constellation Orion to find Castor and Pollux. Draw an imaginary line from the westernmost star of Orion’s Belt and through the bright ruddy star Betelgeuse to locate the Gemini stars. Chart via the International Astronomical Union.
Chart showing Big Dipper to Castor and Pollux.
If you’re a far-northern stargazer, you can also use the famous Big Dipper asterism to star hop to Castor and Pollux on November evenings. You must be far north because – for most of us – the Big Dipper is below the horizon on November evenings. But far-northern stargazers will see it in the north to northeast.

Bottom line: The waning gibbous moon shines in the vicinity of the Gemini stars Castor and Pollux on November 21 and 22, 2021.

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November 21, 2021

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