Tonight and tomorrow night – November 27 and 28, 2015 – 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. They are Castor and Pollux in the constellation Gemini. From mid-northern latitudes, the threesome appears over the horizon by around 9 to 10 p.m. In the Southern Hemisphere, the stars Castor and Pollux won’t climb over the horizon until much later tonight.
The constellation Orion is also fairly close to the moon on November 27 and 28, 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.
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.
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.