Dozens of planetary nebulae are visible in a small telescope, but none present such a distinctive and accessible appearance in a small telescope as the Ring Nebula (M57) in the constellation Lyra. Visible from north and south, the Ring Nebula is a tiny silver-grey smoke ring set in a rich and beautiful section of the northern summer Milky Way.
The Ring Nebula is perhaps the easiest planetary nebula to find. It lies about 3/5 of the way from gamma Lyrae to beta Lyrae in the southern end of the Lyre, itself marked by the brilliant blue-white star Vega which rises overhead in the mid-summer months.
M57 is small, just 76″ across, but it appears non-stellar at 25-30x in a 3″ scope. And at 80-100x, the famous two-toned oval smoke ring pops into view. This 9th-magnitude nebula is surely visible in binoculars, but it appears very small and indistinguishable from the background stars.
A short video tour of the Ring Nebula through a small telescope.
The outer part of the ring is lighter, but you’ll notice even the inner section is brighter than the background sky. Averted vision helps bring out detail in the nebula. And it helps you see many sparkling foreground and background star, which pop into view as you turn your gaze away from the nebula. These stars look like sugar frosting on a small celestial donut.
The video above gives you an idea of what M57 looks like in a 6″ scope at 200x, though you won’t see colour through your eyepiece.
The central star of the ring, a star about the size of our own Sun, began blowing off its outer layers about 20,000 years ago, and these layers now form the nebula. Its tenuous gases are set aglow by the blazing hot stellar remnant near the centre. Bereft of its outer layers, the central star of the Ring Nebula will now become a white dwarf. This hot blue star is very faint… about magnitude 14 or 15… and only visible in 12″ or larger telescopes.
The Ring Nebula is about 2,000 light years away and spans about 0.4 light years. From our skies, the nebula continues to expand from the central star at a rate of about 1″ per century.
The nebula is actually hourglass-shaped, much like the well-known Dumbbell Nebula (M27). While we see M27 edge-on, we’re looking at the Ring Nebula nearly end-on.
You’ll never tire of observing the Ring Nebula. Beginners love it because it’s easy to find and pleasing to the eye. Experienced stargazers enjoy it because it reminds us of the days long ago when we first saw this lovely nebula, of how much we’ve seen since then, and of how much more we hope to see.
Bonus Object: Look for the faint globular cluster M56, Lyra’s other Messier object, about halfway from gamma Lyrae to beta Cygni. The cluster itself is hard to resolve in a small scope, but this faint smudge sits in a beautifully star-rich patch of sky.