The Stars of Autumn
With fewer hours of sunlight during autumn the nights grow longer and there is a distinct chill in the air after the sun sets. You may notice the sky appears darker and the stars just a little clearer. A star chart or an astronomy app for a phone or tablet will guide you to the fall constellations and many of the stars visible in our skies.
Low on the horizon in the south lies the brightest star of autumn, 1st-magnitude Fomalhaut, in the constellation Piscis Austrinus, the Southern Fish. Fomalhaut is in an area devoid of other bright stars, making it fairly easy to spot. From our northerly latitude it is sometimes called the “Loneliest Star” and is famous for being the first star with an exoplanet directly viewed through a telescope!
An easy-to-recognize pattern in the autumn sky is the W of Cassiopeia, (the Queen,) tilted on its side high in the northeast. Below the W is Perseus, (the Hero,) a constellation containing two interesting objects.
First up is the star Algol, also known as the Demon Star because of the way it brightens and then dims —a pattern the ancients thought was caused by a supernatural being. This dimming and brightening happens because Algol is an eclipsing binary-star system, where a larger, but dimmer, star moves in front of a brighter star every 2 days, 20 hours and 45 minutes.
The other highlight in Perseus is the Double Star Cluster—a fuzzy patch to the naked eye that becomes two separate clusters of stars through binoculars. There are about 700 stars between the two, which are thought to be separated by 200 light years. Both clusters lie at a distance of 7500 light years from Earth.
Finally, using your star chart or astronomy app, see if you can locate the faintest object visible to the naked eye, the Andromeda Galaxy. In dark skies, it will appear as a faint, fuzzy patch of light. At 2.5 million light years it will be a challenge to see. If you find it, you won’t be disappointed!
“Western Slope Skies” is produced by members of the Black Canyon Astronomical Society. This episode was written & recorded by Ricky Smith.