Finally summer! Beginning on the 21st with the advent of the Summer Solstice, June marks the official beginning of the long awaited Lawnchair Season. Besides getting the grill ready for festive feasts and digging those all too tiny speedos and bikinis out of storage, windows to the summer universe come into view above the evening treetops.
One of these very famous, though oddly shaped bay windows is, of course, the Summer Triangle. Within the borders of the triangle are some of the Lawnchair's favorite summertime trophies. Its main components are: Deneb, the Head of the Northern Cross in Cygnus; the very bright Vega in Lyra; and lastly, the star Altair of the constellation Aquila. Two smaller constellations, Sagitta and Vulpecula, also sit within the borders of the triangle.
Well after the sun sinks below the horizon in the west, by 10 p.m. all of these constellations can be seen well above the eastern horizon. From a location not bordered on the east by the glowing light of a nearby city or town, all of their jewels can easily be viewed against a dark, contrasting background, clear of any turbulence, often common during the often steamy evenings of late summer.
A wide-angle sweep from the Sagittarius Teapot rising above the southern horizon toward the reclining Northern Cross of Cygnus in the east, traces the path of the summer Milky way. Cygnus is actually the Swan in mythological representations and, is quite easy to locate. In a moonless sky, both the light and dark bands of the Milky Way are dramatically apparent, depending on how dark your chosen observation sight is. A sweep along its main cross beam with binoculars or a small scope will delight even the most seasoned amateur. In a big scope and a wide-angle lens, the star fields are superb. The detail of the knotted dark nebulae against the brightness of millions of pinpoint stars of the Summer Milky Way must be seen to be believed. Of course there are the big attractions in Cygnus, too. The bright clusters and nebulae are typical stopping points on a Lawnchair adventure.
Speaking of stopping points, catching the foot star of the cross in the eyepiece is often the place where, if you've brought along fellow enthusiasts, lingering looks are to be expected. Even in a pair of binoculars, or a small telescope, Albireo, the foot of the Northern Cross, is simply one of the most beautiful double stars in the sky. Its constituents, a bright blue giant and an equally striking golden yellow senior citizen, make this a regularly visited target for the Lawnchair. There are, of course, thousands, if not millions of double and triple star systems. But the contrasting colors of Albireo and its mate make this one of the most special to view in person. Binoculars are all that you'll need to see this exceptional phenomena.
As for other easy Lawnchair targets, expanding out about midway between Albireo and the Lyra constellation, M 56 is a subtle Globular Cluster. Another target can be found near the intersection of the cross beams. M-29 is a sparse open cluster with a few large members and several accompanying, though minor constituents. The entire area along the cross is flush with thousands of dim pinpoint stars, best seen in binoculars and telescopes employing wide angle lenses.
But there's more than meets the eye within the realm of Cygnus. Invisible to optical instruments, the very famous Cygnus X 1, an x-ray source not detected until the nineteen seventies, was one of the first candidates for evidence of a Black Hole. I prefer the term Black Star, since, after all, that's what it really is.
When a star ends its life, having expended all of its available fuel, it initially expels its outer shell and its remaining mass falls inward, crushing itself into an incredibly dense core that either becomes what we know today as a rapidly rotating pulsar or, in the case of the most massive stars, a black hole (star). The remaining object is so dense that the gravity it creates is strong enough to keep light itself from escaping. Hence the name. In the case of Cygnus X-1, it feeds off a nearby massive blue giant star whose in-falling materials produce the energetic radiation our space-based instruments can detect in the x-ray spectrum.
The gathered data from the orbiting Chandra telescope, the Rossi X ray Timing Explorer and, the Advanced Satellite for Cosmology and Astrophysics, has been crunched and it is currently calculated that Cygnus X 1 or its "event horizon" the point of no return for material falling into a black hole, is rotating at more than eight hundred times a second. It's also been determined that Cygnus X 1 weighs in at nearly fifteen times the mass of our sun and lies over six thousand light years away.
Next up is Lyra, home to the very bright star Vega, another point of the Summer Triangle. From antiquity Lyra represented a common musical instrument (Lyre). You could never say that these early viewers didn't have vivid imaginations! To my eye, this small grouping of stars resembles a warped letter K. The treasure here is M-57, the Ring Nebula. It is one of the most famous and enigmatic sights of the summer season. Where once shone a massive star, all that remains now is a glowing ring-shaped shell of charged particles, the remnants of an ancient novae. Residing between the foot stars of the imaginary K, the Ring Nebula is one of the most famous Deep Sky Objects (DSO) and perhaps one of the easiest to find. You'll need a medium to large telescope to experience this sight in all its glory. It's a view that you will never forget.
Lastly, Aquila and the star Aldebaran mark the third point of the Summer Triangle. Another of the bird constellations, (Eagle) Aquila is also embedded within the thick star fields of the summer Milky-Way. There are countless, though very dim clusters and nebulae within its borders. Wide angle views are best here as well.
Be aware, though, that using any type of optical aid, a telescope or binoculars for instance, will need time to adjust to the outside temperatures. The reason for this is to equalize the temperature of the air inside your instrument to the outside temperatures so that images at the eyepiece will remain clear and steady. Air currents can and do produce havoc on magnified images. Especially when the warmer air inside your telescope, having been nestled safely in the warmth of its indoor place of honor, first meets the colder air from outside. Until equalized, the viewing will be somewhat compromised, especially at high magnification levels. However, once the temperatures have equalized, about twenty minutes should do, you'll be ready to point and enjoy this early look at some of Summer's best sights.
The Lawnchair Astronomer
Gerry Descoteaux is the author of “The Lawnchair Astronomer,” a Dell Trades paperback. He has been writing about astronomy for more than 25 years. He also played an integral role in the development of America Online’s pioneering distance education program known as AOL’s Online Campus and served as Professor of Astronomy there for 10 years. He can be reached at TheStarMan@thelawnchairastronomer.com.