Jimmy Westlake: Saturn joins the planet parade
March 9, 2010
On March 21, the ringed planet Saturn will be at its closest point to the Earth for the year, a point called opposition.
At the moment of opposition, the Earth is positioned directly between Saturn and the Sun, placing the two planets as close together as they can be.
Oppositions of Saturn happen about every 12 1/2 months as the faster-moving Earth gains a lap on Saturn and catches up to it from behind. This year, on March 21, Saturn will be 780 million miles from Earth.
When Galileo pointed his telescope at Saturn in 1610, he noticed what looked like "ears" or "cup handles" on either side of the planet. It was about 50 years later that Christiaan Huygens recognized that a flat ring encircled Saturn.
The ring is composed of billions of tiny ice particles, probably particles blasted off one or more of Saturn's small, icy moons by the impact of a comet.
And, speaking of moons, quite a large family of worlds and mini-worlds orbit Saturn. To date, astronomers know of 60 moons orbiting Saturn. The largest is Titan, a planet-sized moon with a thick, cloudy atmosphere.
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Saturn, Titan and many other moons are being studied right now by NASA's Cassini spacecraft, which was placed into orbit around Saturn in July 2004.
Spectacular photographs of the Saturn system are beamed back to Earth daily, helping us to understand the mysteries of this distant world.
Check out the latest amazing Cassini images of Saturn at the Web site: http://saturn.jpl.nasa.gov.
You can spot Saturn, without any optical aid, rising in the eastern sky shortly after sunset. It appears as a bright, yellowish star that doesn't twinkle like a regular star but gleams with a steady light. This year, Saturn is positioned in the constellation of Virgo, about a hand span above the bright star Spica.
If you own a telescope — even a small one — try aiming it at Saturn. Saturn offers the biggest "wow" factor of any other object visible through a small telescope. You can easily see for yourself Saturn's magnificent icy rings and its largest moons. Try looking around March 11, 19 and 27, when the giant moon Titan appears farthest away from the rings and is easiest to spot. Titan will look like a little orange "star" just beyond the edge of the rings. You might see several other, fainter moons hanging around the rings, as well.
Saturn's rings were positioned edgewise to Earth in the fall and are just now tilting themselves into our view again. In the months ahead, the rings will appear through a telescope like little spikes on either side of the planet.
The viewing angle will continue to improve in the next few years, though, as Saturn opens his rings up into full view.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published around the world. His "Celestial News" column appears weekly in the Steamboat Pilot newspaper. His "Cosmic Moment" radio spots can be heard on local radio station KFMU. Also, check out Jimmy's Web site at http://www.jwestlake.com.
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