The Prettiest Globular in the Sky
If my time was fast running out on this earth and I had but one night left for stargazing, I’d have to spend some of my final hours studying the celestial riches of Scorpius and Sagittarius. These grand starry regions, which lie in the direction of the center of the Milky Way, hold a treasure chest of celestial wonders unmatched anywhere else in the sky.
It’s all here. Diffuse nebulae like M17 and M8. Open star clusters like M7 and the False Comet. Globular star clusters like M4 and M80. Not to mention the thick star clouds and dark nebulae of the Sagittarius Arm of the Milky Way. Truly spectacular. (If you’re unfamiliar with this part of the sky, p.36-42 of our Binocular Tour of the Night Sky will get you acquainted).
Perhaps the finest globular cluster in this region, if not the entire sky, is the unappreciated M22, located just above the Teapot of Sagittarius. It’s not the brightest glob, nor the biggest, nor the closest. But it is perhaps the prettiest and easiest to resolve, especially in a small telescope. Astronomy writer Rod Mollise calls M22 the “Arkenstone in the stars”, after the famous white gem in Tolkien’s tale of “The Hobbit”.
Why is M22 so striking? I think it’s because more famous globs like M13 in Hercules and omega Centauri, while brighter, are also tighter and denser, and so much harder to resolve into individual stars in a small telescope of 3-6″ aperture. Not so with M22… this cluster is more spread out, so you can its individual stars even in a small telescope. Yet the cluster spans as much sky as the full moon so there are a lot of stars to see. Visually, M22 also has an unusual elliptical shape.
You can easily find M22 just 2.5 degrees northeast of the top star in the teapot of Sagittarius, Kaus Borealis. Its right ascension is 18h 36m 24 s and its declination is -23° 54′ 12″… ideal for southern hemisphere observers, but still accessible near the horizon to us northerners on a clear, dry late summer night.
Messier 22, just 2.5 degrees NE of Kaus Borealis
As with all deep-sky objects, find M22 at lowest magnification, then proceed to higher magnification to take in more detail. Don’t rush. Take in the view slowly and carefully. You won’t want to miss a thing.
And if you only have binoculars, don’t despair. You won’t resolve stars in this cluster, but you will still get a splendid view of M22 in this rich region of sky. You might even see it with your unaided eye.
M22 has some 70,000 ancient stars roughly 12 billion years old. It may once have been part of a small galaxy absorbed by our Milky Way. The cluster lies 10,400 light years from the tip of your telescope.
