by I think any good book on astronomy would have a photo of what could best be described as the “smoke ring” of the sky. Others may call it a cosmic donut or bagel, but this object’s common name is the Ring Nebula, located in the constellation Lyra, the Lyre. Although Lyra is generally considered a summer constellation, it is still very well positioned for viewing, now more than two weeks into the autumn season.
Go out this week at about 10 pm local daylight and head due east. About two-thirds of the way up from the sky, you’ll see a brilliant blue-white star. This is Vega, the brightest star in Lyra. The only other star at that time that surpasses Vega in brightness is yellow-orange Arcturus in the constellation Boötes, the Herdsman. But the rest of the sky will have Arcturus, about halfway up in the southwest.
The constellation Lyra was supposed to represent Apollo’s harp. A fainter star forms a small geometric pattern of parallelograms connected at the north corner of a triangle on one side. Vega shines at the western end of the triangle. The two lowest stars in the parallel are Beta and Gamma Lyrae. Beta is also sometimes called Sheliak and Gamma is also called Sulafat. Between these two stars, but a trifle closer to Sulafat is where you will find the Ring Nebula.
Want to see the Ring Nebula or another nebula for yourself? Be sure to check out our guides to the best binoculars and the best telescopes.
And if you’re interested in your own impressive skywatching photography, don’t miss our guide on how to shoot the night sky. We also have recommendations for the best cameras for astrophotography and the best lenses for astrophotography.
A heavenly curiosity
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Antoine Darquier de Pellepoix of Toulouse, France first saw the Ring Nebula in January 1779. Using a telescope of about 3 inches aperture, he described it as a perfectly circumscribed disk about the size of Jupiter, but dull in light and appearance of a fading planet. .
A short time later, Charles Messier also saw it and added it to his catalog of comet occulters listing it as Messier 57, or M57. But like de Pellepoix, Messier’s telescope was too dark to give a true picture of what he was looking at. “It appears to be composed of very small stars,” wrote Messier, adding, “but with the best telescope they cannot be distinguished; they are only doubtful.”
It was not until six years later, in 1785, that Sir William Herschel (the discoverer of Uranus) saw M57 as a ring. “It is among the curiosities of the heavens; a nebula with a regular concentric dark spot in the center.” Herschel, however, mistakenly assumed that he was looking at “the ring of stars.”
Gas shell or tunnel?
As for the true nature of the ring, it is generally believed that at some point in the past, a star that was nearing the end of its life and all its nuclear fuel had exhausted large masses of gas out into space in a gaseous shell. This surrounding gas is still expanding and is visible by the light from its extremely hot central star (which is just the core to the left of the original star). The surface temperature of the star is estimated at 216,000ºF (120,000ºC). Our own sun is expected to undergo a similar process in a few billion years.
The Ring Nebula is the most famous and among the brightest examples of what astronomers refer to as “planetary” astronomers. But despite their name, planetary nebulae have nothing to do with planets. This is because they generally appear in telescopes not as stellar sources, but as small diffuse discs.
For a long time, the explanation for the appearance of the Ring Nebula was that the hazy disk was so much brighter around its edges that it looked like a ring; that we are looking through the edge of the far gaseous shell. Therefore, there is much more gas in our line of sight and the refraction of light from the central star makes it brighter, as each particle acts as a prism or mirror, and reflects the rays back to us.
However, more recent research has confirmed that it is probably a ring, or torus of bright material around its central star. In fact, based on photos taken from the Kitt Peak National Observatory near Tucson, Arizona, some people think we may be looking down on a gas tunnel shaped like a barrel or cylinder.
See it for yourself
As for seeing the ring for yourself, it shines at magnitude +8.8, so it’s far too faint to see with the unaided eye. Any good pair of binoculars will find it, although it will look almost star-like due to its small apparent diameter. The shape of the ring may become visible to most eyes in small telescopes using 100-power magnification, although a 6-inch telescope at least is recommended to see the ring clearly. With larger instruments and higher magnifications, the ring appears clearly as a “ghostly little doughnut.”
You might ask if the central star is visible within the “nut hole.” The answer is “yes and no.” The magnitude of this star is about +15. That means it’s almost 4,000 times smaller than the faintest star you could see with your unaided eyes. And don’t bother looking for the central star unless you have a telescope with an aperture of at least 12 inches. Even then, you’d need a dark and clear, really dark night to even get a brief glimpse of it.
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But once, almost half a century ago, in 1975, I saw it. It was the annual midsummer Stellafane convention, just outside of Springfield, Vermont. The Ring Nebula was one of the objects visible through the 12-inch Porter turret telescope atop Breezy Hill. Needless to say, though, my eyes were much younger then, and the overall level of light pollution in much of New England was much less than it is now.
Bottom line: sure, you shouldn’t have any problem seeing the Ring Nebula, but its central star would probably stay out of your reach.
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Free natural history magazine,the The Farmers’ Almanac and other publications.
