Gems in Cygnus

Cygnus the Swan flies high in the western sky during the early evening hours this month. The Milky Way is espe­cially bright in this area of the sky, often defying the choking grip that light pollution has on suburban skies. Many striking binocular targets are nestled in its gentle glow.

Let’s begin at the crux of the Swan, the star Sadr. The name “Sadr” comes from the Arabic word for “chest,” which describes its position within the celestial swan perfectly.

Also known as Gamma (γ) Cygni, Sadr is an ideal jumping-off point for our first target, open cluster M29. M29 floats a little less than 2° to the star’s south-southeast. Charles Messier was first to lay eyes on it back in July 1764, when he described it as “a cluster of seven or eight very small stars . . . which one sees . . . in the form of a nebula.” Through my 10x50s, M29 does indeed look like a tiny, rectangular nebula of grayish light. Moving up to my 16×70 giant binoculars resolves those stars Messier mentioned. They form a small dipper-shaped pattern that some liken to the Pleiades. Four of the cluster’s brightest members create a rectangular bowl, while a fifth can be imagined as a stubby handle.

Cygnus holds a second Messier object that is easy to spot despite its more remote position in the constellation. M39 is one of my favorite early autumn open clusters. It lies 9°, or about 1.5 binocular fields, northeast of Deneb [Alpha (α) Cygni]. To find it, center your binoculars on Deneb and then slowly move northeastward along a meandering row of six irregularly spaced 4th- and 5th-magnitude stars. M39 is just beyond the easternmost star in that line. Look for a tiny, triangular grouping of about a dozen faint points. While M39 itself is weak in terms of the number of stars it holds, the rich surroundings demand that it be savored slowly. By sitting back and relaxing your eyes, you may get the illusion of depth, as if M39 were suspended in front of a blanket of more distant suns.

Cygnus holds many objects that put our eyes and our binoculars to the test. One of my favorites is the North America Nebula, NGC 7000. The North America Nebula is a large expanse of glowing hydrogen gas mixed with opaque clouds of cosmic dust just 3° east of Deneb and 1° to the west of 4th-magnitude Xi (ξ) Cygni.

Deneb was once believed to be the power source ionizing the hydrogen gas in NGC 7000, but more recent studies prove that the very hot 6th-magnitude star HD 199579, buried within the nebula, supplies the energy.

This celestial continent spans 2°, or four times the width of the Full Moon. This makes it too large to easily see through conventional telescopes. But the wide fields of our binoculars make them perfect for the task. In his classic work Burnham’s Celestial Handbook, author Robert Burnham Jr. advised, “Binoculars show an irregular glow more than 1½° in diameter with the North American shape becoming unmistakable on a clear night.” The nebula is so bright that under a very dark sky you can see it with naked eyes alone.

The brightest parts of the North America Nebula are “Mexico” and “Florida.” Both jut into an “empty” expanse of dark nebulosity just east of Deneb in much the same way as their earthly counterparts mark the Gulf of Mexico’s shoreline. Can you make them out?

I’d love to hear about your favorite binocular objects and feature your observations in future columns. Please send your suggestions to me at ­binophil@outlook.com.

Until next month, remember that two eyes are better than one.