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Starwatch NewsletterMinnesota Starwatch is a newsletter describing the night sky in the Midwest.
It is updated monthly, and is produced by the |
Minnesota Starwatch for August 2009
If we can get away from city lights and choose a moonless night, August is the best month to admire our Milky Way Galaxy. First, though, a monthly update on the Solar System, our back yard in the universe.
The MOON is full on August 5th, and unfortunately will still be bright a few days later for the annual Perseid meteor shower. Every year in early August, the Earth moves through a stream of comet-debris and we see lots of meteors hitting the upper atmosphere. If you stare upward in the late evening of Tuesday-Wednesday August 11th and 12th, you may be able to see a shooting star every two or three minutes -- but after 11 p.m. the Moon's brightness will make them harder to spot.
Currently the only impressive evening planet is JUPITER, rising in the southeast around sunset and crossing the southern sky near midnight. In mid-August the Earth is exactly between the Sun and Jupiter. MERCURY and SATURN can be seen in the early evening just after sunset, but they're not very obvious right now, as they are low above the western horizon.
VENUS and MARS are morning objects in the eastern sky before sunrise. Mars is now pretty far away -- 160 million miles -- so it's not very bright. As for Venus, she's starting to move around to the other side of the Sun and will disappear in October. The crescent Moon is fairly close in the sky to Mars and then Venus on the mornings of August 16th and 21st respectively.
After the middle of this month, if you're lucky enough to be under a clear dark rural sky, the MILKY WAY passes overhead, a hundred million times farther away than those planets we just mentioned. Most people know that the Milky Way is our Galaxy, but here's an exercise in imagination. The Sun and solar system, and all our neighbor stars a few lightyears away, move in 200-million-year orbits around the center of the Galaxy. We're about 25 thousand lightyears from the center. Now, stand under a clear dark late August sky around midnight, facing south. Galactic Center is just above the southern horizon in the constellation Sagittarius. Straight overhead, the constellation Cygnus is the direction in which we're moving! Imagine yourself as a sort of vector arrow, with the top of your head pointing forward along our Galactic orbit. If you could move straight upward like Superman, still facing Sagittarius, you'd be moving ahead of the Sun. Keep facing toward the Galactic center as you go, and in a few hundred million years you might catch up with the Sun and nearby stars from behind. Cosmic orbits of this type helped lead to the discovery of Dark Matter two or three decades ago.
The Department of Astronomy's summer Universe in the Park program continues during the month of August with events at Lake Maria, Afton, William O'Brien, Gooseberry Falls, Tettegouche, Father Hennepin, Mille Lacs Kathio, and Nerstrand Big Woods State Parks. Events will be held on Friday and Saturday nights and will begin with a short presentation on one of a number of astronomy topics ranging from the Solar System to the History of the Matter, followed by telescope viewing of the night sky (assuming cooperative weather, of course). The program is free and open to the public, so feel free to bring your friends! More information can be found at www.astro.umn.edu/outreach/uitp/.
The Como Planetarium in St. Paul's Como Park offers limited star shows. For more information, call (651) 293-5398 or check their website at www.planetarium.spps.org. If you're interested in how you can help build the new Minnesota Planetarium, please call 612-630-6151 or visit www.mplanetarium.org.