Want to be a stargazer? Image is everything

Dr. Mario Motta built his first telescope at age 14. It took him a year to construct the 8-inch reflector, and he proudly won a science award with it.

Now 55 and a physician at North Shore Cardiovascular Associates in Salem and vice president of the Massachusetts Medical Society, Motta still has the astronomy bug. He recently completed a 32-inch relay design telescope, which transfers images through mirrors and lenses, that took three years to build. He ground his own optics and machined the metal parts.

But the result is worth it, says Motta, who likes to look at galaxies and nebulas and recently woke up at 4 a.m. to take advantage of a clear night. "It's fascinating," he says.

Merely purchasing a telescope, however, doesn't guarantee you'll clearly see the Orion Nebula or Saturn's rings. Many a telescope has ended up in the back of a closet, unused, after the typical promise of "seeing the sun with 500 magnification" resulted in nothing but fuzzy images.

"Don't buy on impulse just because you see something in a store," says Alan MacRobert, senior editor of Sky & Telescope magazine. "You can't buy your way into this hobby; just like you can buy a surfboard but you can't be a surfer till you learn to surf."

Many budding astronomers make the mistake of purchasing what Motta calls "the typical department store telescope," with a long, tubelike focus refractor. "These aren't bad for looking at the beach or birds, but they are terrible for the sky," he says. "They have a small field of view, don't track objects as they move, and have poor light-gathering ability."

Since the primary function of a telescope is to gather light, the aperture, or diameter of the lens or mirror, is critical for quality viewing. A refractor telescope uses lenses to focus light; reflector telescopes use mirrors; and a compound, or Schmidt-Cassegrain, uses both lenses and mirrors. Refractors are easy to use and best for viewing moon and planets but are more costly than reflectors.

Motta recommends that beginners start off with a good Dobsonian-mounted telescope. These are reflector telescopes that look like a cannon on a swivel and are easy to set up and don't have complicated controls. Try a 6- to 8-inch aperture from makers such as Meade or Celestron, for about $400.

The large aperture throws up a bright image of globular star clusters, planets, and other celestial objects.

Whether it's a reflector, refractor or compound, it's crucial to have a stable mount that allows the telescope to move smoothly as you follow objects across the sky.

"Does the telescope jiggle when you focus? If every time you aim, the telescope wobbles, it can be frustrating," MacRobert says.

Computer-operated telescopes, with databases of locations, allow you to "go to" that elusive galaxy by synchronizing the telescope's coordinate system with the sky.

Don't think you need a big telescope. Noreen Grice, operations coordinator of the Museum of Science planetarium , said usually a powerful pair of binoculars (7x50) or (10x50) can provide just as clear heavenly vision.

Given the right atmospheric conditions, darkness, and quality optics, you'll be able to see a whole new universe above you -- craters on the moon, comets, galactic clouds, and star clusters. It won't look like the explosion of colors in the Hubble space telescope photos, but rather remote, distant objects.

"But it's like the ocean," Grice says, "a whole new frontier."