The Sky This Week, 2012 October 9 - 16
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Messier 11, the "Wild Duck" Cluster in Scutum |
The Moon continues to wane in the morning sky, slimming down to a thin crescent before she gets lost in the glare of morning twilight toward the end of the week. New Moon occurs on the 15th at 8:03 am Eastern Daylight Time. If you have a small telescope, Luna occults the northern half of the galactic star cluster Messier 67 in the constellation of Cancer on the morning of the 10th. On the morning of the 12th she will be just over six degrees southwest of the dazzling planet Venus.
With the Moon now well clear of the evening hours it’s another great week to explore the deeper realms of the autumn sky. During the course of an evening you can see some of the best examples of different "deep-sky" objects that keep amateur astronomers riveted to their telescopes all night long. During the early evening hours you will find wonderful examples of different types of star clusters and softly glowing nebulae. The finest globular star cluster in the northern sky, Messier 13, hangs high in the west at the end of evening twilight. This cluster, which can be seen as a glowing round patch in binoculars, resolves into thousands of tiny stars as you increase the aperture of your telescope. Located in the constellation of Hercules, this cluster is famous for a coded radio message beamed in its direction by astronomer Frank Drake in 1961. At the speed of light that message should arrive in about 25,000 years! A fine example of a galactic star cluster may be found in the star clouds of the Milky Way near the bright star Altair in the Summer Triangle. Messier 11 lies about 20 degrees southwest of Altair in the small constellation of Scutum, the Shield. Popularly known as the "Wild Duck" cluster, it is my favorite object of its class in the sky. A modest telescope can track down Messier 57, the "Ring Nebula", in the southern side of the small parallelogram of stars the, together with the bright star Vega, make up the constellation of Lyra, the Harp. At low magnifications the nebula looks like a ghostly planet disc, hence it’s termed a "planetary nebula". Under higher power it looks like a small translucent smoke ring.
As the night passes the Milky Way and its attendant bright stars begin to settle in the west, and a dimmer set of stars climb toward the meridian. Autumn’s constellations are for the most part dim and scattered since we’re looking away from the plane of the Galaxy. In this part of the sky you’ll find distant galaxies lurking among the fainter stars. The brightest of these is Messier 31, the Great Andromeda Galaxy, which we discussed last week. Also lurking in this part of the sky is Messier 33, the "Pinwheel Galaxy", which lies about halfway between the bright star Mirach in Andromeda and Hamal, the brightest star in Aries, the Ram. M33 is often considered a "challenge" object for the small telescope, but I have often spotted it in binoculars as a hazy patch of light about the same apparent diameter as the disc of the Moon. Literally hundreds of more distant galaxies can be spotted in large telescopes in this part of the sky. If you’d like to hunt some down, you can join amateur astronomers on Saturday evening the 13th at Sky Meadows State Park near Paris, Virginia. If it’s clear amateurs will be out in force with telescopes large and small. Details on this event may be found here.
Back in our own solar system, we find ruddy Mars still lurking in the southwest during late evening twilight. This week he closes in on the star Antares in the constellation of Scorpius. "Antares" means "Rival of Mars", and by the end of the week you’ll have a good chance to compare them as their separation dwindles to less than five degrees.
Giant Jupiter continues to make progress into the evening sky. He now rises before 9:30 pm, and by 11:00 he’s high enough to get a good view in the telescope. Even though he’s still nearly two months from opposition, he’s worth looking at whenever he’s above the horizon. Old Jove is far and away the best planet for observing with small telescopes. Even if you can’t see his dark atmospheric cloud belts, his four bright moons will provide interesting views on any given night.
Dazzling Venus still beckons in the pre-dawn sky. You’ll have no trouble finding her in the gathering morning twilight as she retreats from her recent close encounter with the bright star Regulus in the constellation of Leo, the Lion. She will receive a visit from the waning crescent Moon before dawn on the 12th, then spend the rest of the month alone among the fainter stars of the springtime sky.
