Originally catalogued by the Greek astronomer Ptolemy in the 2nd century, the constellation Lyra is nearly overhead as July begins for northern hemisphere observers at temperate latitudes and crosses the meridian around mid-night EDT (04:00 UT) on July 18/19.
According to Greek mythology, Lyra is associated with the great musician Orpheus who was killed by the Bacchantes. Orpheus was the son of king Oeagrus and the muse Calliope. When Orpheus was young the god Apollo gave him a lyre made of gold and taught him to play it. He played it so well that even the rocks and trees were charmed by his music. As a companion of Jason and the Argonauts, Orpheus made it possible for the Argonauts to get past the Sirens whose song enticed sailors to come to them. When the Argonauts approached the island where the Sirens lived, he drew his lyre and played music that drowned out the Sirens’ calls. Orpheus was killed by the Thracian Maenads who were maddened during the Bacchic rites, ripping him to shreds for not honoring Dionysus, and tossed his lyre into the river. Zeus (our man about town) sent an eagle to get the lyre and placed both of them in the sky. Of course there is quite a bit more to the story of Orpheus and his lyre but the brief accounts I mention here pretty much summarize his fate.
The constellation Lyra offers a few interesting stars as well as two Messier objects for the small telescope. If you don’t have an atlas, you can download and print the IAU/S&T constellation map at left by clicking on it.
The fifth brightest star in the night sky is Vega (α Lyrae) and the second brightest star in the northern sky. Vega shines with an apparent magnitude of 0.03 and is about 25 light-years distant. At two times as massive as our own Sun, it is believed to be only 455 million years old – about half of its life expectancy, which makes it about a tenth of the Sun’s age. Vega also has the distinction of being the first star to be photographed and have its spectrum recorded. On 17 July 1850, William Bond and John Adams Whipple imaged Vega at the Harvard College Observatory but it was an amateur astronomer named Henry Draper who took the first photograph of Vega’s spectrum in August of 1872.
An area of astronomy where the backyard astronomer can make a real contribution to the science is variable star observing and the constellation Lyra provides an excellent starting point with the eclipsing binary star beta Lyrae (Sheliak). β Lyrae’s orbital plane is lying near our line-of-sight so that the components periodically eclipse one another causing a decrease in the apparent magnitude. The orbital period for β Lyrae is 12.9 days and the period is increasing at a rate of about 19 sec/year. The range in magnitude is 3.4 to 4.3 at mid eclipse. Should you become hooked on this fascinating aspect of our hobby, the AAVSO (American Association of Variable Star Observers) provides everything you need to get started making light estimates of variable stars. β Lyrae is one of the stars recommended for beginners and is included in their 10-Star Training Tutorial.
Here’s a star that has long been considered a test for your telescopes optics. ε Lyrae or better known as the Double Double. The widest two components are easily separated with binoculars or finder scope. The northern star is called ε1 and the southern star ε2 . Each of these stars can be split with higher magnification into two separate double stars making four star altogether. I was able to get a clean split using the 120mm refractor at 150x and all four stars appear white and nearly equal in magnitude. We would like to hear about your observation of this interesting multiple star system.
One of the original discoveries of Charles Messier is the globular cluster he catalogued as M56. M56 (NGC 6779) is located between γ (gamma) Lyrae and β (beta) Cygni (Albireo). Although the cluster is listed as magnitude 8.3, its low surface brightness of magnitude 12.9 makes M56 one of the less bright clusters of the Messier globular clusters. In the 90mm f/10 refractor under the light polluted skies here at the observatory, M56 is a very faint and barely visible at 34x. The cluster is best seen with averted vision but still not resolved. Increasing the power to 65x does increase the contrast but still need averted vision to detect.
One of the showpieces of the summer night sky is M57 (NGC 6720) the Ring Nebula. Discovered by Antoine Darquier de Pellepoix in January 1779 just a few days before Charles Messier found and cataloged it, described it as “a dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet.” M57 is very easy to locate between β Lyrae and γ Lyrae. In the 90mm f/10 refractor at 34x, M57 is a small gray dot set against a starry background. Increasing the power to 91x, the object clearly shows the ring with a slight greenish tint. Do you detect a slight ellipticity when you look at M57? We’d like to know what you see with your telescope.
That’s it for this week. Remember, if you observe under light polluted skies like we do, try to get out after 11:00 PM local time when some businesses turn off their signs and traffic is down to a minimum. There’s truth in the saying “it’s always darkest before the dawn”. Try to observe when your target objects are straight overhead, at the Zenith. This is always the darkest part of the sky. Invite your friends and neighbors over for an observing session. After seeing the effect of light pollution on observing, they may be more cooperative in turning off their lights for you. Most of all, we’d like to hear from you. At the top of each post is a “Leave A Comment” link. Just click on it and tell us what you think or see with your telescope or binoculars. You can login with your Twitter or Facebook account. It’s quick and easy. Want to see more of Richard Flinn’s astrophotography? Here’s a link to his gallery.