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Sirius Rising

December 6, 2013

Sirius — the brightest star in the night sky — is often associated with summer. It rises with the Sun at that time of year, ushering in summer’s “dog days.”

But summer is the worst time to watch Sirius. It’s either too close to the Sun to view, or it rises not long before sunrise. Instead, the best time to watch Sirius is during late autumn and into winter, when it’s in the sky for most of the night. Tonight, for example, Sirius rises around 9:30 or 10, and remains visible throughout the night.

Sirius looks so bright for a couple of reasons. First, it really is bright — it produces about 30 times more energy than the Sun. And second, Sirius is less than nine light-years away. Only a few stars are closer.

Sirius is actually a binary — two stars that move through space together, bound by their mutual gravitational pull. The star that we see with the unaided eye is Sirius A. The other is Sirius B. Since Sirius is known as the Dog Star, Sirius B is nicknamed “the Pup.”

Sirius A is a main-sequence star. That means that like the Sun, it’s in the prime of life. Sirius B, on the other hand, is a white dwarf — the burned-out core of a once-normal star. It shines only by releasing the intense heat it built up during its long lifetime. It’s so small, and so close to Sirius A, that you need a telescope to see it.


Script by Damond Benningfield, Copyright 2013

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