When I talk to people about observing here in town, they often bemoan the fact that light pollution makes stargazing all but impossible from within the city limits.
Though it is true that observing from an urban setting doesn’t compare to an experience under truly dark skies, it’s certainly not the case that there’s nothing to see from one’s own backyard or even sidewalk.This month I’ll consider some of the sights in the constellation Lyra, which is almost directly overhead throughout August in early evening.
Lyra is a tiny constellation, but it holds a wealth of lovely double stars that are bright enough to be seen without a pilgrimage to the deep, dark countryside.
The constellation Lyra is easy to find on clear nights. Vega, its brightest star and the brightest star of summer, is nearly overhead at sunset. Vega marks one apex of the famous Summer Triangle, an asterism of three bright stars high in the summer skies. Lyra itself though is small formed of a triangle of stars attached to a larger parallelogram. Classically, the constellation was seen as a harp or lyre.
My observations are made with a six-inch reflecting telescope from my own yard in Kankakee, but a smaller telescope will reveal these sights as well. You’ll want to use eyepieces that give a relatively low magnification. (I used about 40x. Calculate the magnification of your eyepiece by dividing your telescope’s focal length by the focal length of your eyepiece. A shorter eyepiece focal length gives greater magnification.)
Sometimes you want higher magnification, as when you’re viewing the planets or the Moon and want to see details, but for the following views a lower magnification is better.
Start your tour with Vega, especially if you’re new to stargazing. A single star doesn’t look much different through a telescope, but this will give you a chance to align your finding scope (if your telescope has one) and test your instrument’s focus. It will also give you an idea of the seeing conditions for the night. If you can focus Vega down to a brilliant, sharp point, and if you can see one or two of its dimmer companions in your telescope’s field of view, you should be able to spot the rest of the objects in this list.
Hop down from Vega to Zeta Lyrae, the dim star where the triangle meets the parallelogram. This is one of the many double stars in Lyra. Double stars are great targets for light polluted skies. Unlike nebulae or galaxies, they are fairly bright and thus easy to enjoy even from one’s own backyard. Through even a small telescope, Zeta Lyrae is revealed to be a wide, uneven double, and many observers report seeing a beautiful color contrast between the component stars.
Moving up to the third star of the tiny triangle that makes up the top portion of Lyra, we find Epsilon Lyrae, one of the most popular double star systems in the sky and an example of why some observers (like me) get so excited about double stars. At 40x you may simply see what looks like a wide pair of white stars. But if you increase your magnification (I used 130x), you’ll see that each of these stars is actually itself a pair of stars. The entire system is known as the “Double-Double.” You’ll need a steady eye and good seeing to split them, but you’ll know if you’ve succeeded by noticing the orientation of each tight pair: they’re inclined at ninety-degrees to each other.
Moving back to a lower magnification, each of the stars at the apexes of Lyra’s parallelogram is a treat.
Delta Lyrae is a wide double star in a diffuse cluster of stars. One of the components is a lovely orange in contrast to the surrounding blue stars.
Beta Lyrae also is a group of colorful stars. (The Ring Nebula is nearby, halfway between Beta and Gamma Lyrae. From my front yard, the Ring Nebula at 70x looked like a faint smoke ring, barely visible.)
But my favorite sight of all in Lyra is a bit off the beaten path and not terribly well known. It’s sometimes called the “Double-Double’s double,” but I think it’s actually nicer than the more famous Double-Double. It’s a pair of double stars, like the Double-Double, known as Struve 2470 and 2474. They’re dimmer than the pair that make up Epsilon Lyrae, but because the components are farther apart they’re easier to split. They also have more marked colors, the brighter components appearing yellow in contrast to the dimmer bluish companions. Moreover, by some cosmic coincident the pairs are orientated in the same direction so they indeed look like almost perfect twin double stars in a single telescope eyepiece. This view alone would be proof enough for anyone who says the city skies are too bright to hold telescopic wonders.
Struve 2470 and 2474, the “Double-Double’s Double,” image from bestdoubles.wordpress.com.
This column first appeared in the Kankakee Daily Journal.
Stephen Reid Case 