Halloween sky promises spine-tingling cosmic treats
Late October skies offer great stargazing opportunities.
Wed, Oct 27 2010 at 4:31 PM
HALLOWEEN NIGHTS: The "Ghost of Mirach" galaxy as seen in the ultraviolet by NASA's Galaxy Evolution Explorer observatory. (Photo: NASA)
Late October evenings are the perfect time to explore the wonders of the deep sky. With naked eye, binoculars or a small telescope, there is a veritable Halloween candy bucketful of sky objects worth looking at, and the evenings are still mild enough to make the journey enjoyable.
Halloween, in particular, is an ideal opportunity for a bit of "sidewalk astronomy," weather permitting. If you have a telescope, this is a prime opportunity to set it up for trick-or-treaters and offer a cosmic addition to their traditional sugary fare.
This seasonal night sky map points out several possible targets for late October stargazers.
The moon, Jupiter and some of the objects in this autumn skywatching guide are excellent targets. The Owl Cluster in Cassiopeia is particularly tantalizing.
Dark, not scary, night skies
The most important tip for observing deep sky objects is to get away from the light-polluted skies of the city and find a suburban or rural location where these faint distant objects will shine through.
Your local astronomy club has probably scouted out the best locations in your area, and most clubs hold regular gatherings called "star parties" at these dark locations. There, you will get the best views of these fascinating objects and be able to view them with a variety of telescopes.
When you face east on an autumn evening, you will see a wide array of stars above the bright star Capella in the constellation Auriga. The most recognizable landmark is the bright "W" of Cassiopeia, visible in all but the most light-polluted skies. To the W's right are the double chains of stars that mark Andromeda. Below it, in the direction of Capella, is the constellation Perseus.
Cassiopeia, your night sky Halloween escort
Let's use Cassiopeia as our starting point. Located in the plane of the Milky Way Galaxy, Cassiopeia is rich in open-star clusters. These are easy targets for binoculars or small telescopes.
Close by, the bright star Ruchbah is a compact but rich star cluster catalogued by Charles Messier as number 103. On the opposite side of Ruchbah is the Owl Cluster, named for its fancied resemblance to an owl.
Many observers think it looks more like the movie character "E.T." than an owl.
If you use the upper three stars of the Cassiopeia W as an arrowhead, they point to the Andromeda Galaxy.
Although visible to a trained eye without any optical aid, this galaxy is more easily seen by beginners with binoculars. It looks like a very faint wisp of smoke against the dark sky. In a telescope, it continues to resemble a faint cloud of smoke, but is seen to be accompanied by two smaller galaxies, Messier 32 and 110.
These satellite galaxies are farther away from the main galaxy than you might think from photographs, since the main galaxy is usually overexposed in photographs and much larger than it appears in the sky.
Cosmic ghost in Andromeda
An interesting, and often overlooked, object in Andromeda is the "Ghost of Mirach." It is a galaxy very close to the star Mirach in the middle of the lower chain of Andromeda stars. [Photo of the Ghost of Mirach galaxy]
In a medium-size telescope it looks like a faint echo of the bright star. Almach is one of the prettiest double stars in the sky.
Almost directly overhead in the remote northern reaches of Andromeda is the so-called "Blue Snowball." This is a planetary nebula: a puff of gas set off by a dying star. Viewed through a telescope, it is very small and very bright, easily mistaken for a star, except for its unusual blue color.
Below Cassiopeia, in the direction of Capella, lies the constellation Perseus.
At the heart of this constellation, surrounding the star Mirfak, is the Alpha Persei Star Cluster. Only 600 light-years away, this is one of the nearest star clusters.
Between Mirfak and Cassiopeia lies the Perseus Double Cluster. Just visible to the naked eye, this is one of the most glorious deep sky objects, whether viewed in binoculars or a small telescope.
There are many other objects of interest in Perseus, such as the eclipsing binary star Algol, the rich star cluster Messier 34, and the "Little Dumbbell" planetary nebula, Messier 76.
If you are blessed with truly dark skies, have a look for Messier 33 in Triangulum, just underneath Andromeda.
Although this is one of the nearest and brightest galaxies, it is extremely difficult to see because of its large size, poorly defined edges, and low surface brightness. It takes a dark sky and a moderately large telescope to spot its faint glow.
This article was reprinted with permission from SPACE.com.
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