September: Some planets, constellations swing into view

Posted: Sunday, September 05, 2004

Uranus and Neptune are the evening planets this month, appearing very low in the south to southeast in the late evening. To find Uranus, binoculars are advised. Also, check out or similar observing Web pages or the April through September issues of Astronomy and Sky & Telescope magazines at the Kenai, Soldotna and KPC libraries. They feature charts and information that is easier to follow than I could describe here.

Both planets are faint and just on the brink of being observable with the naked eye, hence my advice for binoculars. The best observing time in September is around midnight and the best observing place may be a beach on Cook Inlet with an unobstructed view toward the south that's because they're just 15 degrees above the southern horizon.

The planets are in the faint constellations of Aquarius and Capricornus, which makes it easier, in my opinion, to spot them because there are plenty of faint stars to compare them to. As I indicated, the charts in those publications listed will help you find them.

How do you know which is a planet? For one, Uranus should show a hint of green through binoculars, though Neptune's bluish tint probably won't show. You also can make an observation one night, come back a week later and you'll notice the planets have retrograded to the right.

Other planets are visible in the morning before sunrise. All month long, look for bright Venus above the eastern horizon. Early in the month, notice Saturn as well as the twin stars Castor and Pollux just above of Venus. Throughout September, Venus will move away from Saturn into Cancer and Leo. The accompanying drawing shows a view due east around Sept. 10 when these planets are joined by our waning crescent moon. Around those dates, wait until dawn and find Mercury rising on the eastern horizon.

Jupiter and Mars are not visible this month but will become morning planets later this fall.

For the stars, here is a rehash since we now are able to actually see stars in once again dark environs for the evening sky. To orientate yourself, find the Big Dipper low in the northwest, then extend the dipper's last two stars high into the north to find Polaris, the North Star, and the Little Dipper.

With the Big Dipper on one side of Polaris, find the constellation Cassiopeia, a nicely shaped W, on the other side of Polaris high in the northeast. Back to the Big Dipper, follow the curve of its handle toward the bright red giant Arcturus low in the west with its constellation of Bootes above, appearing as a kite or cone shape. Notice the bowl-shaped Corona Borealis to its upper left.

Prominently high overhead and extending to the south is the Summer Triangle, made up of the three bright stars Vega, Deneb and Altair. Deneb's constellation of Cygnus, the Swan, in a cross shape is easily seen. Vega's small rectangular-shaped Lyra, the Harp, is prominent as well. Altair's Aquila, or Eagle, may be depicted by its wings.

Just on the upper left of Altair is the dolphin-shaped small constellation Delphinus. Also prominent in the southeast are the great square of Pegasus and, low in the northeast, bright yellowish Capella with its pentagon-shaped constellation Auriga.

By morning, constellations have rotated toward the west with some of them having set while other have risen in the east. Those are Orion, Taurus, Gemini, Cancer and Leo as well as the planets described above.

Have fun observing. I'm looking forward to clear skies this winter and for the astronomy class I'm teaching this fall.

Andy Veh is the physics and astronomy instructor at Kenai Peninsula College. This column appears on the first Sunday of each month. He can be reached at

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