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CYGNUS
The Swan
Cygnus - Alexander Jamieson - 1822
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Swooping and soaring through the middle of the Milky Way, Cygnus the swan joins Aquila, the eagle, as the two great birds of the Milky Way. Cygnus, sometimes referred to as the northern cross, is unmistakable as a huge, long-necked swan with outstretched wings, flying straight down the middle of the Milky Way. And the Milky Way is where the action is. That's where everybody lives. That's where all the stars are. When we look at the Milky Way, we are looking down through almost the entire length of the saucer shaped disk of our galaxy, and seeing billions and billions of stars, and a lot of other things too. When we're not looking at the Milky Way, we are looking up through a relatively thin layer of stars - a few thousand at most - out into the blackness of intergalactic space.
The alpha star in Cygnus is the first magnitude (1.25) Deneb. Together with Vega and Altair, it forms what some like to call the summer triangle. Deneb is a A2 blue-white supergiant, one of the largest, hottest, brightest stars in the heavens. It is 60,000 times brighter than our Sun. The only reason it doesn't light up the night sky as if it were day, is because it is very far away - over 1,500 light years.
The beta star, Albireo, is actually the fifth brightest star in the constellation. The origins of its name are speculative at best, and over time it has come to be known simply as the beak star. It has a magnitude of 3.08, and is 380 light years away.
Gamma Cygni is the star Sadr, Arabic for chest. Like Deneb, this star is a massive supergiant, 65,000 times brighter than the Sun, far away at a distance of 1,500 light years, and with a magnitude of 2.2. It is slightly cooler than Deneb, having a spectral class of F8 yellow-white supergiant.
Epsilon Cygni is named Gienah Cygni, the wing of the swan. It is the closest of the named stars in Cygnus, residing only 72 light years away. With a magnitude of 2.48, it is classified as a K0 orange giant.
Like Sagittarius, Cygnus is in one of the busiest places of the Milky Way, full of star clusters and nebulae almost too great to number. The largest and most impressive of these is the side by side North American Nebula, (NGC 7000) which really does resemble the continent of North America, and the Pelican Nebula, (IC 5750) which looks for all the world like the close-up profile of a long billed Pelican.
Just as large, but with a much lower surface brightness, and difficult to see without filters and time exposures, are the east and west sections of the Veil Nebula, NGC 6992 and NGC 6960 respectively. Their majesty and splendor are captured below and graciously submitted into the public domain by noted astronomer, Adam Block.
Like Lyra, Cygnus is in the target zone of the state of the art planet hunter, NASA's Kepler Space Telescope. Launched in March, 2009, it is the most light sensitive telescope ever built, for the sole purpose of discovering exoplanets. To avoid contamination, Kepler is millions of miles away from Earth, in its own orbit around the Sun. For the next four to six years, Kepler will remain focused on one spot, simultaneously and continuously monitoring the light from the same 100,000 stars, to detect the minute changes caused by a planet transiting (crossing in front of) one of them. A small area between Lyra and Cygnus was chosen for its abundance of stars and its lack of interference from the Sun and other light sources. For more information on the Kepler mission, go to http://kepler.nasa.gov/.
So far Kepler and ground based telescopes have found twenty exoplanets in Cygnus. The good news is that several of these planets are not much larger than Earth, and therefore have a higher probability of harboring some sort of extraterrestrial life. The bad news is that the stars hosting these planets are all very far away and well beyond the limit of naked eye visibility. However, the Kepler mission has only just begun, and the number of planets is expected to rise dramatically, so stay tuned.
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