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What's In The Sky

Stargazing for September

By JIM WHITE

September is probably my favorite month for stargazing. Nights grow longer, and we don't need to wait as late in the evening for darkness. Yet, nights are still pretty warm, making evening stargazing still comfortable. Finally, the weather is usually pretty good, with clear nights and transparent skies.

A piece of trivia that I missed in July was the anniversary of Neptune's discovery. Neptune was discovered one year ago...one Neptune year, that is. The outermost planet of our solar system was discovered on Sept. 23, 1846. Neptune takes 164.8 Earth years to orbit the Sun, and completed its first circuit since discovery on July 12 of this year.

Neptune, and its neighbor Uranus, are visible in the evening sky this fall. Both lie in the southeastern evening sky in September, Neptune in the constellation Aquarius, Uranus in Pisces. Neptune is too faint to see with the naked eye, and requires a telescope or binoculars.

Uranus is closer to the Earth, and brighter. It can be seen from dark skies with the naked eye, but looks just like other dim stars, so you need to know which one it is. Star charts showing the location of both planets are available on the internet at http://media.skyandtelescope.com/documents/Uranus-Neptune-2011.pdf

September will be ushered in by a picturesque crescent Moon, located just to the left of the bright star Spica, low in the west after sunset. Full Moon will occur on Sept. 11, with new Moon following Sept. 26. On Sept. 15 and 16, the waning gibbous Moon will be near Jupiter, in the late evening and early morning sky.

Jupiter is becoming the prominent evening planet in our sky. Saturn begins the month very low in the west, right after sunset. By the end of the month, the ringed planet will be located near Venus, very low in the west, in the Sun's glare.

Jupiter, on the other hand, is becoming easier to see in the evening. On Sept. 1, the solar system's largest planet rises at about 10 p.m. By the end of the month, it rises just before 8 p.m., and is high enough to see well by 10 p.m.

Located in the constellation Aries, it will be the brightest "star" in the eastern sky, to the right of the star cluster Pleiades.

September is a great time to view our galactic neighbor, the Andromeda galaxy. The galaxy lies in the constellation Andromeda, from which it gets its name. Although it is so distant that light from it takes over 2 million years to reach us, the combined light of its billions of stars makes a soft glow that is barely discernable with the naked eye, and easy to spot with binoculars. Look for it high in the eastern sky in September.

On Aug. 5, I saw my first aurora borealis (northern lights) since 2003, a dim, diffuse glow in the north. Our Sun has been quiet for years now, but is awakening toward a maximum of activity predicted for 2013. That means a greater chance of northern lights in the next couple of years. I'll address the northern lights in a future column.

If the stars interest you (you'd probably not have read this far if you are not!), there is a great online resource for viewing the stars, planets, and constellations. Stellarium, a planetarium program, simulates the sky we see. You can download it (for free) at www.stellarium.org.

You will need to enter your location -- you can enter your latitude and longitude, or use Portland, Ore., which is in the program's database and is pretty close. Give it a try!

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