December 26, 2002
Richard Tresch Fienberg, Editor in Chief
617-864-7360 x144, rfienberg@SkyandTelescope.com
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Every holiday season, hundreds of thousands of shiny new telescopes are given to good girls and boys (and moms and dads) around the world. Be it a long, sleek tube or a compact marvel of computerized wizardry, every new telescope surely has an owner itching to try it out. And why wait? Winter evenings often feature crisp, transparent skies with a dazzling canopy of stars. But with so many inviting targets overhead, where should you point first?
"Most telescopes provide fine views of the Moon and bright planets," advises Richard Tresch Fienberg, editor in chief of Sky & Telescope magazine, "and these are traditionally the first celestial targets tracked down by budding starwatchers." This coming week the Moon is a waning crescent in the predawn sky, Fienberg explains, and it won't return to the evening sky until about January 4th. Even so, plenty of other impressive "first lights" can be seen after sunset and none are more impressive than the giant planets Jupiter and Saturn, which right now are placed for prime viewing.
Saturn and Its Rings
You can spot Saturn as soon as it gets dark. Face east and look for a dominant "star" about 20° (the width of both your fists held at arm's length) above the eastern horizon. Saturn is especially bright right now, outshining all the stars in that part of the sky thanks to a happy coincidence of three geometric effects. First, the planet is near perihelion, the closest point to the Sun in its 29-year-long orbit. Second, Earth and Saturn are particularly close together in space, only 750 million miles apart. And finally the planet is tipped toward us at its maximum angle, showing its beautiful rings to their fullest extent.
Many veteran skywatchers credit their first telescopic view of Saturn with sparking a lifelong interest in astronomy, and it's easy to see why. Even the smallest telescope will reveal the planet's pale-yellow globe completely encircled by the dazzlingly white rings, which consist of countless icy particles ranging in size from small grains to large boulders. If the air is steady, use a magnification of 100x or more to spot a dark, narrow gap in the rings. Called the Cassini Division, it separates the inner B ring from the outer and slightly narrower A ring. Keep an eye out for a little "star" in Saturn's vicinity; that's Titan, the planet's largest moon.
Jupiter and Its Moons
Stay out a little later, and you'll see Jupiter slowly climbing above the east-northeast horizon. Right now this giant planet appears five times brighter than Saturn in fact, it outshines every star in the sky. "Jupiter is the king of planets," notes veteran observer Gary Seronik, an associate editor at Sky & Telescope. "It's big, it's bright, and it has moons that do interesting things." Even at 100x, you should be able to make out a pair of dusky bands girding Jupiter's midsection. These dark equatorial "belts" and the bright "zone" between them are cloud features akin to jet streams high in the Jovian atmosphere. (Jupiter, like Saturn, is a gas giant with no solid surface.)
According to Seronik, larger telescopes (with main mirrors or lenses at least 6 inches in diameter) will bring a few more belts and zones into view, along with an assortment of spots and streaks. The famous Great Red Spot, a huge cyclonic storm larger than Earth, has been rather pale in recent years and can be easily overlooked. Jupiter rotates in just 9 hours, 55 minutes, and the Red Spot is easiest to see when it's crossing the middle of Jupiter's disk.
While watching Jupiter, your eye will immediately be drawn to a series of moons roughly aligned with the planet's "stripes." These are the Galilean satellites, named for the famous Italian astronomer Galileo, who discovered them in 1610. Over time you'll notice their movement as they shuttle around Jupiter. Sometimes not all four moons are visible: occasionally one of them ducks behind Jupiter or is hidden in its shadow. In larger telescopes they (or their shadows) can be glimpsed crossing the planet's disk.
Other Sky Sights
There's more to the night sky than planets, of course, and some of the best celestial treats are on display on December and January evenings. The familiar constellation Orion climbs in the east after sunset. Look for a distinctive trio of bright stars in a nearly vertical line: the Hunter's Belt. Just a few degrees to their south (lower right), you'll find the Orion Nebula, a luminous, swirling cloud of gas and dust where stars are forming by the hundreds. This nebula is obvious in any telescope, and a high-magnification eyepiece should reveal a tight quartet of stars near its center called the Trapezium.
Meanwhile, to Saturn's upper right, about halfway from the horizon to overhead, your eyes will be drawn to a tight knot of stars called the Pleiades. This grouping is also known as the Seven Sisters, and in Japanese it's called Subaru look for them on this automaker's logo! Through binoculars or a telescope at low magnification, the Pleiades cluster shows dozens of stars. Astronomers have found that the entire cluster has about 500 stars in all.
"To get the most from your new telescope, be patient," advises Fienberg. "Spend time with each object, and get to know it. Much of what the universe has to offer is sublime." Too many first-time telescope users expect an explosion of Hubble-like color through the eyepiece, he explains, when in fact our night vision sees almost everything as shades of gray.
More tips on skywatching and how to get the most out of your telescope can be found in our Observing Section. You can even create a customized sky chart for your location, showing the stars and planets for any time or date.
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About Sky Publishing
Sky Publishing Corp. was founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer, the original editors of Sky & Telescope magazine. The company's headquarters are in Cambridge, Massachusetts, near the Harvard-Smithsonian Center for Astrophysics. In addition to Sky & Telescope and SkyandTelescope.com, the company publishes an annual magazine called SkyWatch as well as books, star atlases, posters, prints, globes, and other fine astronomy products.