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January 24, 2016

The Moon is just past full tonight, so it casts a brilliant glow across the winter landscape. Unfortunately, it casts that same glow into the sky. Its light is scattered by molecules in the air — the same thing that happens with sunlight, only not as bright. Still, it’s enough to overpower the view of many fainter stars — leaving the night sky looking a bit washed out.

Luckily, there are plenty of bright lights that shine through the moonlight. Several of them are in Auriga, the charioteer, which is high overhead in mid to late evening.

Several of its stars form a lopsided pentagon. The brightest is Capella, one of the brightest stars in the entire night sky. It represents a small goat riding on the charioteer’s shoulder.

It’s actually a binary — two stars locked in orbit around each other. Both are yellow giants — stars that are much bigger and brighter than the Sun. They’re also much later in life than the Sun, which is why they’ve puffed up.

The third-brightest point in the pentagon is Menkalinan, which represents the charioteer’s other shoulder. It, too, is a binary. Its stars are aligned in such a way that they eclipse each other every couple of days, causing the system to dim a little bit. The more massive star is also getting along in life, so it’s just beginning to puff up. Before long — astronomically speaking — it’ll get much bigger and brighter — making it even easier to spot the charioteer through the moonlight.

Script by Damond Benningfield, Copyright 2015

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