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Watch for the moon and the Twins

Tonight – November 7, 2017 – and tomorrow night, before going to bed, look for the moon in your eastern sky. It’ll be a bright waning gibbous moon, and you might notice two bright stars in its vicinity. These stars are noticeable for being both bright and close together on the sky’s dome, and that is why – in legends of the sky – they often represent Twins.

The stars are Castor and Pollux in the constellation Gemini. From mid-northern latitudes, they appear over your horizon with the moon by around 8:30 to 9:30 p.m.

In the Southern Hemisphere, the stars Castor and Pollux won’t climb over the horizon until later tonight. 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.

EarthSky lunar calendars are here! Don’t miss ’em

The constellation Orion is also fairly close to the moon on November 7, and the Giant Hunter might dazzle you with his 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.

Several days from now, when the moon drops out of the constellation Gemini, you can always star-hop to Castor and Pollux from Orion. Simply draw an imaginary line from the bright star Rigel through the bright star Betelgeuse, going a solid two times the Rigel-Betelgeuse distance. This way of finding the Gemini stars Castor and Pollux works in both the Northern and Southern Hemispheres.

When the moon is no longer around to guide you, star-hop to Castor and Pollux from the constellation Orion. Simply draw an imaginary line from the bright star Rigel through the bright star Betelgeuse, going a solid two times the Rigel-Betelgeuse distance

When the moon is no longer around to guide you, star-hop to Castor and Pollux from the constellation Orion. Simply draw an imaginary line from the bright star Rigel through the bright star Betelgeuse, going a solid two times the Rigel-Betelgeuse distance

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, so you can use the Big Dipper bowl to star-hop to Castor and Pollux.

Use the Big Dipper bowl to star-hop to Castor and Pollux

Use the Big Dipper bowl to star-hop to Castor and Pollux

At more southerly latitudes, as in the northern tropics and the Southern Hemisphere, Orion rises before Gemini.

The starry sky is one great big connect-the-dots book. Learn how to star-hop with certain key stars, and you can more easily orient yourself to the night sky when traveling to faraway latitudes.

Bottom line: The waning gibbous moon offers some guidance tonight, as its shines between the constellation Orion and the Gemini stars Castor and Pollux.

EarthSky astronomy kits are perfect for beginners. Order yours from the EarthSky store.

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Bruce McClure

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