You are here


January 24, 2015

One “dog” star leads another across the sky on winter nights. Procyon, the little dog, precedes the Dog Star, Sirius. They’re in good view in the eastern sky by a couple of hours after sunset.

Sirius is the brightest star in the night sky, so it’s easy to find. Procyon is off to its upper left. It’s not quite as bright, but it’s still one of the brighter stars around, so you shouldn’t have any trouble picking it out.

The name Procyon means “before the dog.” It indicates that from middle-northern latitudes and above — say, anywhere northward of about Dallas — Procyon rises a little before Sirius. In cultures where Sirius played a prominent role in religious and public life, the first appearance of Procyon in the dawn sky was an alarm clock — it alerted people to the return of Sirius a few days later.

Procyon itself closely resembles its brighter canine cousin. Both stars are bigger, brighter, and heavier than the Sun. But Procyon’s a little farther away — about 11.5 light-years, versus 8.6 for Sirius — so it doesn’t look quite as bright.

Also like Sirius, Procyon has a “dead” companion known as a white dwarf. It’s the core of a star that was once bigger and brighter than Procyon itself. It used up all the nuclear fuel in its core, though, so the core stopped producing energy. The star’s outer layers then streamed off into space, leaving only the dead core — a cosmic ember that trots along with the little dog star.


Script by Damond Benningfield, Copyright 2014

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.