If you check your North American bird guide (pages 22–23) you’ll see that there are three species of swans in North America: the native Tundra Swan and Trumpeter Swan, mostly in the West, and the introduced Mute Swan, mostly in the East. (A fourth species, the Eurasian Whooper Swan, is an occasional visitor to western Alaska.) That’s a fun fact to know.
But there’s an even bigger swan that you can see “migrating” every night at this time of year—the constellation Cygnus, the great swan of the heavens, that appears directly overhead on fall evenings, passing to the west overnight and disappearing over the horizon.
Cygnus is one of my favorite constellations. It’s simple and easy to recognize, and you can clearly see it as a flying swan, with long outstretched neck, short tail, and spread wings. If you’re in a dark sky location you’ll see that the Milky Way passes right along the swan’s length and does indeed give it a whitish appearance.
The River Houses reference library includes a handy set of sky maps and a planisphere that will show you the location of Cygnus and its most prominent stars. The description of Cygnus appears on page 12:
Cygnus is a beautiful, easily recognized constellation in the form of a giant cross; it is sometimes called the Northern Cross. Deneb, a brilliant white star of magnitude 1.3 (18th of the 20 brightest stars), marks the top of the cross. There are many bright stars in Cygnus; it lies directly in the Galactic Plane and [therefore to the eye appears] embedded in the Milky Way. Sweep this entire are with binoculars and note the many stars and clusters.
Spend a little time out after dark this week with your students and locate the great swan as it makes its nightly migratory flight. Once you learn to spot it, you’ll have a new autumnal friend for life.