Jimmy Westlake: ‘Planets on parade’
June 29, 2008
For the next couple of weeks, the evening twilight will serve as a colorful backdrop for a remarkable parade of planets, specifically, the Red Planet, Mars, and the Ringed Planet, Saturn. Throw in a bright star and a crescent moon, and the parade gets even better!
Mars and Saturn are passing through the stars of the constellation of Leo right now and happen to be very close to Leo’s bright alpha star, Regulus. The trio can be spotted in the western sky during deep twilight, which this time of year occurs between 9:30 and 10 p.m. Mars is the faintest of the three and, of course, the reddest. Saturn is the brightest and the highest of the three. Regulus has a blue-white color and twinkles rather furiously compared to the two steady planets.
On Monday night, Mars will make its closest approach to Regulus, passing a mere 0.7 degrees north of it. That’s barely enough room to fit a full moon between them! By the next night, Mars will have passed Regulus and be headed for Saturn. Watch the gap between Mars and Saturn shrink during the next week until, on the night of July 10, the two planets will appear only 0.6 degrees apart. Both worlds should fit easily within the same field of view of a low-power telescope for an unforgettable view! The famed rings of Saturn are visible with as little as 30-power.
Planet appulses, or conjunctions, like this are really optical illusions. In reality, Mars is 202-million miles from Earth and Saturn is nearly five times further, at 928-million miles away. It just so happens that the two planets lie along the same line of sight as viewed from Earth and appear very close together in our sky when, in fact, they are hundreds of millions of miles apart.
Perhaps the real highlight of July’s planet parade comes on the nights of July 5 and July 6 when the slender crescent moon joins the Saturn-Mars-Regulus trio. On Saturday, all four celestial bodies will line up in a straight line across the sky. Saturn, Mars and Regulus will be equally spaced, looking very much like the familiar three stars of Orion’s Belt. The next night, the moon will have passed the planets and appear to their lower left. Catch all of this action before 10:30 p.m. and the planets sink below the western mountains.
While you are gazing at Mars, try to picture the Opportunity and Spirit rovers and the new Phoenix lander as they explore our neighboring world, and when you look at Saturn, imagine the Cassini spacecraft orbiting among Saturn’s rings and moons, beaming back amazing photos every day.
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The planet parade continues into the month of August when the two inner planets, Mercury and Venus, team up with Saturn and Mars for a sky full of planets!
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 on the websites of CNN.com, NASA’s “Astronomy Picture of the Day” website, Spaceweather.com, Space.com, Discover.com, MSNBC.com, NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His “Celestial News” article 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.