LOOKING UP: Find the Andromeda Galaxy
With the Moon now past full, dark starry evenings - if clouds cooperate- are bringing the beauty of autumn skies to your backyard. Constellations marking autumn evenings are generally dim, but should be no less fascinating. The Milky Way Band continues to arc across the heavens, but the wider and more prominent portion seen due south in summer is now receding into the west.
Remember, this hazy band, which looks somewhat like a smoke trail from some grand wood stove, is the cross-section of our flat Milky Way Galaxy of which we are a part. Our spiral galaxy has a prominent, fatter hub in the middle, from which the spiral arms extend. The bright and glorious hub is better seen from deep south, especially below the Earth’s equator. From mid-northern latitudes such as in Pennsylvania, the hub is only partly seen, and is low on the south horizon on summer evenings. By the time of mid-autumn, the region of the galactic hub is already below the southwestern horizon at night fall. This leaves us the narrower and slightly dimmer Milky Way Band, stretching around the sky. You need a clear, moonless night to see it, away from town and shopping plaza lights.
Ever try stargazing from Wal-Mart’s parking lot? Don’t. Naturally they need their lights, but in such a setting you will still see the Moon and brightest of stars and planets. Your eyes are also not adjusted for the darkness there. Don’t look up there for long or your cart might get away! It would be ludicrous to do away with all outdoor lighting. No one in their right mind would suggest that. Then again, we could hand out red-covered flashlights to everyone... Seriously, many modern light fixtures today are built to keep the glare from your eyes and from the sky. They use shields that direct the light downward where it is intended, and at the same time, less wattage is required. Unfortunately, many older outdoor lights still brighten the night unnecessarily.
The autumn sky returns to us a cleaner window into the Universe. Dust is almost everywhere in the galaxy, making up clouds called “nebulae.” Stars are formed from dust clouds. The dust is mainly concentrated along the Milky Way arms and especially the hub. As we look out away from the hub, there is less cosmic dust. Astronomers find a much greater abundance of outer galaxies in the regions of the sky well away from the Milky Way Band.
The most easily visible neighboring galaxy is now well seen in the evening. The Great Andromeda Galaxy, also known as M31, is one of the closest galaxies to our own and is part of what is called the “Local Group,” an assembly of galaxies in this neighborhood of the Universe which travel together, bound by one another’s gravity. On the next clear, dark night, have a look yourself. M31 appears as an elliptical, hazy smudge, quite dim but readily seen once you know what to expect and where to look.
Never mind the wonderful photographs of the Andromeda Galaxy you may have seen, showing bright and detailed. They are taken with telescopes and long exposures. Even the view through a small telescope won’t show that much, although it is still very interesting. Binoculars will help you a great deal. With them you will more easily discern the elliptical shape and see that the center is brighter.
The galaxy is really round like a dinner plate but it appears elliptical due to the angle from which we are situated- the flat circle becomes foreshortened. Other galaxies seen in a backyard telescope appear like a thin line, with a wider, brighter center. This is the “dinner plate” seen from its edge.
To locate M31, face northeast at around 9 p.m. or so (in the latter half of October), and look about three-quarters the way up. Find the bright “M” shaped constellation of Cassiopeia, not quite overhead. The “M” at this time appears on its side. Look to the right of the top right corner star of the “M”, about the same distance as the “M” is tall (as seen in this orientation). This brings you to the dim fuzzy spot which is the Andromeda Galaxy. Binoculars are highly recommended. If you don’t see it immediately, keep scanning the immediate area until you do. Once found it is unmistakable. Then see if you can find it with unaided eyes alone.
Now stop and realize you are seeing an entire galaxy beyond our own Milky Way. It is calculated to be approximately 2.5 million light years away and as much as 260,000 light years wide. Very similar to the Milky Way, astronomers learn much about our own galactic home by studying its big, close neighbor. In 1890, one of Andromeda’s stars blew up. The supernova reached 6th magnitude, visible to the naked eye. A good web site to find more information is www.solstation.com.
Feel free to let the writer know if you found M31.
Be sure to see brilliant Jupiter rising in the east during the evening.
Last quarter Moon is on Wednesday, October 19. Watch also for the Orionid Meteor Shower, which peaks October 21. If there was no moonlight, about 20 meteors an hour might be seen, depending on how late you look and wide open is your view. They seem to radiate from the constellation Orion, which rises over the east horizon around midnight.
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Keep looking up!
