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Moon and Aldebaran

November 14, 2016

The Moon takes dead aim at the face of the bull tonight. It’s to the upper right of Taurus’s v-shaped head as night falls, and nose-to-nose with the bull at first light tomorrow. Binoculars will help you pick out the stars that outline the bull’s face through the lunar glare.

You shouldn’t need any help to pick out the bull’s eye, though. Aldebaran is one of the most prominent members of the autumn sky. In fact, it’s one of the brightest stars in the entire night sky.

If you keep your eye on the Moon and Taurus tonight, you’ll get a good idea of how the Moon moves across the night sky.

Its orbital path carries it through a full circle against the starry background every 27-and-a-third days. At that rate, it moves a distance equal to its own diameter in less than an hour. So from one night to the next, it moves almost half-again the width of your fist held at arm’s length. That’s not especially fast, but with a bright marker like Aldebaran close by, it’s enough to notice over a period of a few hours.

The Moon’s motion against the background of stars isn’t aligned with its phases, though. Since Earth and Moon are moving around the Sun, it takes a couple of days longer to complete the cycle of phases. So the Moon sometimes passes Aldebaran when it’s about full, as it is tonight. But at other times it’s a crescent or at some other phase — different views for its regular meetings with the bull.

Tomorrow: the Moon and a meteor shower.


Script by Damond Benningfield

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