There's plenty of stargazing you can do on a clear night with just the naked eye, but if you're looking to observe the craters of the moon or the rings of Saturn, you’ll need to take the plunge and pick up a telescope. But it's not as simple as just going to a store and picking out the one that looks the best. To make sure you're buying the right one, we spoke to three experts to find out what to look for in your first telescope and what other essential tools you’ll need to go out observing.
Tips Before You Buy
To start, all three of our experts stressed that the best telescope is the one you’ll actually use and that there is no one "correct" model. To find the best one for your needs, the first thing you'll want to do is figure out how much room you have in your home and vehicle, what your budget is, whether you'll be stargazing with a child, and where you want to observe. This will help you find equipment that's in tune with your lifestyle.
Before you make your purchase, you'll also want to look into joining a local amateur astronomers club to find a community of like-minded enthusiasts. Shauna Edson, the astronomy education program co-coordinator for the Smithsonian’s National Air and Space Museum, suggests using the NASA Night Sky Network to find a group in your area. And while you can observe on your own, there are always certain risks that you can avoid with some help. For example, Edson also stresses that you should never go solar observing by yourself as a beginner because of the potential dangers to your vision that could occur when looking through a telescope while the sun is out. For this, you'll definitely want to seek the help of someone with experience in the hobby beforehand.
If you've done some preliminary research and are ready to buy, here are some tips on what you'll need.
There are two basic types of telescopes: refractors and reflectors. Simply put, refractors have lenses in the front that bend the incoming light to form an image at a focal point. "They are what most people typically think of as a telescope: a long tube, and an eyepiece at the end,” Bart Fried, the executive vice president of the Amateur Astronomers Association of New York, tells Mental Floss. They can be portable and are oftentimes easier to use, but they are usually more expensive since the lenses are specially made.
Fried suggests getting a refractor with an aperture diameter of 4 inches or more and an Altazimuth mount (which we'll talk about below). "I think optically, [refractors give] a little better performance," Fried says.
Teagan DePrato-Grable, a product advisor at High Point Scientific, likes the 4-inch refractors because of their portability and the fact that they "will still allow you to see several deep-sky objects under dark skies."
A reflector telescope uses specifically aligned mirrors to reflect incoming light to project an image into your eyepiece. These are a solid option since you can usually get more aperture diameter (basically, more light-gathering ability) for less money because it only has one mirror instead of two special parallel optical lenses. However, a model like this will also be far heavier and cumbersome to bring along on observation trips.
The most popular type of reflector telescope is known as a Dobsonian, which we'll get into below. "A Newtonian reflecting telescope with a 6-inch diameter is enough to show you a ton of stuff," Edson says. DePrato-Grable recommends the 8-inch Dobsonian Apertura AD8 or, for even more detail, the AD10 or AD12 versions.
For a quality telescope on a budget, DePrato-Grable says to aim for above $200. "One can purchase a rather nice Dobsonian or refractor for $350 or less," DePrato-Grable tells Mental Floss via email.
When it comes to basic mounts, there are two main types: Altazimuth and Dobsonian. Altazimuth, also known as alt-az, moves on two planes: up and down (altitude) and side to side (azimuth). Dobsonians, popularized by amateur astronomer (and former Vedantan monk) John Dobson, are simplified alt-az mounts with the reflecting telescope built-in, making them easier for children to handle. DePrato-Grable suggests Apertura Dobsonian telescopes and manual alt-az refractors.
Even though computerized mounts are more expensive and can be difficult to align, they can be great for tracking objects in the sky. DePrato-Grable suggests the Celestron Nexstar SE Series, while Fried suggests new astronomers go simple first and then graduate up to a computerized mount once they know the sky better.
If you're using a telescope with children, Edson suggests a Galileoscope, created in 2009 for the international year of astronomy and the 400th anniversary of Galileo looking through a telescope. It is a DIY plastic refractor that comes with two eyepieces and can easily fit on a camera tripod. "The kids get the experience of seeing all the parts of it and putting it all together with their caregivers," Edson says.
Most telescopes will come with two eyepieces for low and high magnification. Edson says to ignore eyepieces that have an X for magnification—such as X6—and instead get ones that represent the focal length in millimeters. Magnification is determined by dividing the telescope focal length by the eyepiece focal length, both in millimeters. The longer the eyepiece focal length, the lower the power. Since X magnification doesn't tell you the focal length, you won't know if X6 is a low or high magnification.
DePrato-Grable suggests having three eyepieces at various magnifications: A low magnification between 25-35mm can help you scan the sky, a middle-range magnification between 10-15mm is suitable for looking at deep-sky objects, and a high magnification eyepiece between 4-8mm will show you planets up close. He recommends eyepieces from brands like Apertura, Celestron, and Explore Scientific.
Both Edson and DePrato-Grable say that binoculars can sometimes be better than telescopes to see larger objects like nebulae, star clusters, and double stars. Edson suggests binoculars with up to 10 times the magnification and 35mm lenses or higher like this pair from Celestron. DePrato-Grable, meanwhile, recommends the Celestron 8x40 binoculars, saying they provide enough power to "view star clusters, brighter nebulae, and even galaxies under dark skies."
Fried is in the minority and thinks binoculars are best suited for experienced astronomers wanting to scan the sky. Since you usually have to hold them, any movement will blur the image, which can be frustrating for beginners, especially children. "If you're going to buy a nice pair of binoculars and a tripod mount, by the time you're done, you've already spent $200," Fried says. "So why not just spend another $200 and have a telescope?"
5. Star Maps and Resources
"All that astronomy requires is that you look and notice," Edson says. "Telescopes do not teach you the sky. They are an avenue for learning the sky."
To learn more about what you're looking at, Edson suggests apps like Google Sky Map, Sky Safari, and Star Walk for digital star maps. She also likes Skymaps.com, which offers free printable monthly downloads of Northern, Equatorial, and Southern Hemisphere maps, including planets and constellations.
DePrato-Grable suggests using the smartphone app Stellarium. "It will provide exact locations of almost any deep-sky objects or planet that one can see," DePrato-Grable says. He also recommends the book Turn Left at Orion, while Fried prefers the NightWatch: A Practical Guide to Viewing the Universe in the spiral 4th edition.