Prime time to train telescope on Saturn

  • Fri Apr 9th, 2010 3:48pm
  • Life

By Mike Lynch

It’s hard to beat Saturn for planet watching. I so look forward to training my telescope or my Web cam through the telescope at the ringed wonder of our solar system, the second biggest planet in our local families of planets.

Saturn is available in prime time in the Northwest night skies this month. It’s almost at its closest approach, or opposition, to Earth right now. That’s when Earth in its one-year orbit and Saturn in its 29-year circuit line up.

Actually the exact opposition date was March 21, but Saturn is still close at just over 795 million miles away. Saturn occupies our celestial dome all night long, rising at sunset and setting at sunrise.

Saturn’s not the brightest object in the sky, but it’s easy to find: Look to the east after evening twilight. As you can see in the diagram Saturn is shining below the tail of the constellation Leo the Lion. Don’t confuse Saturn with the star Arcturus, which also rises in the east in the early evening. Arcturus is brighter and rises to the left of Saturn, and it has an orange tint to it.

Saturn and its ring system can be easily seen with the smallest of scopes.

The ring system diameter is more than 150,000 miles wide or half the distance between the Earth and the moon. The rings are only 50 feet thick, and every 14 years they are on edge in our view from Earth. That happened this past autumn when Saturn’s rings disappeared. Now you see them just a little bit. In a few years though we’ll get a much better view when more of the north side of the rings are turned our way.

Saturn’s ring system is made up of billions and billions of tiny bits of ice or rocks covered with ice. Some of the debris is the size of a minivan, but most of it is minute. The ice rings reflect sunlight and that’s why they show up so well.

How and why the debris got there is up for debate. One camp says that the debris has been there since Saturn coalesced into a planet more than 4 billion years ago.

Others say that a passing small moon or comet got too close to Saturn about 100 million years ago and was ripped to bits by Saturn’s strong tidal forces. The gravitational effect of several of Saturn’s 60 moons spread the debris into the ring system.

The planet itself is a giant ball of cold hydrogen and helium with no solid surface. Deep within is a rocky core that astronomers believe is about 10 times as massive as Earth. Despite its 75,000-mile diameter it rotates on its axis about every 10 hours.

The largest of Saturn’s 60 moons is Titan, which is bigger than Mercury. Titan has a heavy methane atmosphere and even has methane lakes.

The Cassini spacecraft has been orbiting Saturn for years to collect data and photographs. In one of its latest pictures you can see sunlight reflecting on one of the giant methane lakes. The Cassini spacecraft also photographed water plumes shooting from cracks in a small moon, Enceladus. Wherever there’s liquid water there’s always at least a small chance of some kind of life. There’s bound to be more about this possibility in years to come.

Acclimate your telescope and all its eyepieces for at least a half-hour while you wait for Saturn to rise above Earth’s blurring atmosphere, about 9:30 or 10 p.m. Take long continuous looks through your telescope at Saturn and its moons so your eye gets use to the light level. High level winds are always changing and that can really effect how well you see Saturn or anything else through your telescope.

Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch,” available at bookstores and at his Web site

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