Sky Watch: Buying a telescope
Well, it's that time of year again. The holidays are barreling toward us like an out-of-control sleigh.
If you're considering presenting that special stargazer in your life with a telescope this holiday season -- or even buying one for yourself -- you will do well to answer several important questions before rushing out to spend your hard-earned cash.
First, how well do you (or the gift recipient) know the sky? If you can't distinguish the Ring Nebula from ring bologna, you may wish to purchase a book or collection of star maps instead. Browse a bookstore or telescope shop for suitable material, or consider a subscription to some of the basic astronomy magazines available today.
Second, what are your viewing interests? If the moon, planets or daytime terrestrial scenery are your passion, or if you live under light-polluted skies, a smaller-diameter telescope (two inches or so) will do fine. Otherwise, you'll need a larger "light bucket" (four inches or more) to see fainter star clusters, nebulae and galaxies. However, you'll need to take it to a dark-sky site in the mountains or deserts to use it well.
Finally, what's your budget? Quality telescopes are not toys and you won't find a good one for less than about $300.
As for telescopes, there are almost as many variations as there are eyeballs to look through them. Fortunately, we can divide them into two basic categories. Refractors are more expensive because they use lenses to bend incoming light to a focus. These are generally smaller instruments, and are best for viewing bright objects like the moon and planets. Reflectors use mirrors and, typically, the same price will get you a larger-diameter instrument.
No matter which type of telescope you choose, it must be equipped with a rock-solid tripod or mounting to be useful. And, as far as the new go-to instruments in which a computer aims the telescope for you, I recommend against these for beginners. They're expensive, you'll spend lots of time with the instruction manual learning how to set it up and you won't learn about the sky as you will with an "old-fashioned" manual scope.
So here's my recommendation: first, attend free star parties with your local amateur astronomy club and get a look through -- and at -- a variety of scopes. Some are large and expensive, but you'll get a sense of what you can expect from more modest instruments. Then visit some telescope company websites and check out a Dobsonian-style scope along with a Telrad finder. They're simple, easy to use and relatively inexpensive. I have two of these and use them for all of my public stargazing programs.
Don't discount the use of binoculars! Not only do they offer an excellent transition between naked eye and telescopic viewing, they can also be used for many other activities as well.
If you keep these simple points in mind, your new backyard telescope will provide you and your family with a wonderful and lifelong tool of discovery and won't wind up in the closet alongside the Nordic Track.
To learn more about telescopes and binoculars, visit skyandtelescope.com/howto/scopes.