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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 April 2008
The giant planet Saturn may provide the best viewing this month since it will be visible pretty much throughout the entire night. It can be seen clearly in the southeast at the end of evening twilight, and will then set only an hour or so before morning twilight. Saturn's famous rings should be visible even with a good pair of binoculars. Binoculars or a small telescope give Saturn an oval appearance. The Italian astronomer Galileo was the first to see and record this strange sight. Saturn's poles and also its rings are tilted more than 20 degrees from the plane of its orbit and the April alignment with Earth gives them a very nice presentation. These rings actually consist of myriad tiny moonlets orbiting Saturn, most of them microscopic bits of ice smaller than grains of sand, but some are the size of boulders. Recently, several small moonlets less than a few hundred yards in diameter were discovered orbiting within the rings. Probably there are many more of these yet to be discovered. Remarkably, although Saturn's rings span a distance comparable to the distance between the Earth and our Moon, their vertical thickness is mostly less than the length of a football field. Subtle gravitational pulls from some of the many other moons that orbit mostly beyond the rings bunch the ring material into intricate patterns that include distinct radial gaps and spokes as well as delicate wisps. Many of these features are not easily seen from a distant Earth, but photos of them returned from various space missions certainly are among the most beautiful views of our solar system. The age and origins of Saturn's rings are not entirely clear, although they appear to be debris from one or more shattered small moons. They probably formed several billion years ago when the solar system was young containing many small objects orbiting the sun that could collide with each other and the material around newly formed planets. Our own Moon, in fact, seems to be the result of the collision between a young Earth and a smaller planet during that time.
Mars is also easily visible during the evening hours this month. At sunset it will be high in the southwest a little below two bright stars, Castor and Pollux, in the constellation Gemini (the Twins). Mars is pretty easy to spot because of its ruddy hue. It sets to the west in April, a couple of hours past midnight. About the same time, Jupiter, the largest solar system planet, will rise in the east and will be brightly visible until it fades into the morning twilight. Just before dawn on April 26th and 27th, Jupiter will appear near the waning third quarter Moon.
Friday night telescope viewing at the University of Minnesota Astronomy Department begins at 8pm. Please call (612) 626-0034 for more information. 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.
For fun Astronomy Outreach programs check out our Public Outreach link, or if you're interested in how you can help build the new Minnesota Planetarium, please call 612-630-6151 or visit www.mnplanetarium.org.