Want to view the planets for real instead of a simulation in your web browser? Get a telescope! With a good scope under ideal viewing conditions, it’s possible to observe the rings of Saturn, cloud belts on Jupiter, structure in sunspots (with a safe solar filter), and polar ice caps on Mars. Craters, highlands, and maria on the moon can be seen in exquisite detail like you never thought possible. Even distant globular clusters, faint nebulae, and galaxies can be observed on dark nights when far from city lights. Very rarely, amateur astronomers still discover new comets, asteroids, and supernovae. Also due to the rapid advancement of camera technology in recent years, astrophotography has become much more affordable (e.g. the astrophotography mode of the Google Pixel 4 smartphone). For examples of what is possible, check out r/astrophotography/ where enthusiasts regularly post images of space acquired and post-processed using their own equipment and software. In this article we outline main factors you should consider when choosing a telescope, and provide recommendations for 2021.
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Choosing a telescope in 2021
Larger telescopes collect more light, and thus are able to see fainter objects in more detail. The aperture of a telescope is the diameter of its light-gathering mirror or lens, and is the most important characteristic. There are three basic telescope types: refractor (lenses), reflector (mirrors), and compound (both lenses and mirrors). Reflector telescopes offer the most light-gathering power per dollar, and are popular for beginning astronomers on a budget. In addition to the primary lens/mirror, a telescope also requires an eyepiece (magnifies the image), mount (holds the scope stable), and finder scope (aids in pointing the main scope toward a given object).
The first thing to consider when choosing a telescope is budget. The absolute minimum amount you can spend on a telescope worth buying is probably around $100-$150. Steer clear of any cheap toy “department store variety” telescopes which are nearly always of poor quality and not worth the few dollars spent. If you have less than $100 in your budget, you’re better off getting a more versatile pair of binoculars. If you have more to spend, the best value for your money will most likely be a reflector telescope with the largest aperture you can afford. However, you should also weigh other important factors (such as storage space and portability) before making a final decision.
Before choosing a telescope, determine the local observing conditions in the area you plan to view the sky (check out this interactive light pollution map). Essentially the further away you are from city lights, the better the observing conditions will be. To see deep sky objects (those which exist outside the solar system), a rural area with dark skies is usually required. However, this doesn’t mean city dwellers are out of luck! The moon and many of the planets are often bright enough to be observed even from a large city with moderate to heavy light pollution.
As larger telescopes are able to collect more light and provide better views, it makes sense to get the largest scope within your budget. However, a large telescope may have diminishing returns depending on your living arrangements and where you plan to do your observing. If you reside in small apartment for example, storing a large scope may not be practical. Or if you have limited outdoor space near your home and plan on regularly transporting your telescope to another viewing location, the difficulty of lugging around a huge scope may discourage you from using it often enough to make it worth owning. In these cases, choosing a smaller more portable telescope may be a better option.
Eyepieces determine the magnification. Magnification is defined as the focal length of the telescope divided by the focal length of the eyepiece. For example, a telescope with a 1200 mm focal length using a 10 mm eyepiece would result in a magnification of 120x. Note that higher magnification for a given telescope does not always equate to superior views, and many objects are better viewed at lower magnification. The maximum magnification for a telescope can vary quite a bit, but an oft-cited rule of thumb states that the maximum practical magnification is 50 times the aperture (if measuring in inches) or twice the aperture (if measuring in mm). According to this rule, a telescope with an 8-inch (203 mm) aperture can magnify up to 400x. However, the actual limit depends not only on the aperture and focal length, but on additional factors such as the quality of the optics, turbulence in the atmosphere, and whether the telescope has reached thermal equilibrium with its surroundings. While most scopes include a basic eyepiece, you may eventually want to get multiple eyepieces to cover various magnification ranges for observing different objects. You should also note that eyepieces can be different diameters (usually either 1.25 and 2-inch), so be sure the eyepiece you purchase is compatible with your telescope.
Telescopes require a mechanical structure to support their weight, minimize vibrations, and allow for smooth and precise movements in order to track objects as they move across the sky. A poorly-constructed mount will make it impossible to accurately point the telescope and hold it steady while focusing, which will substantially hinder your viewing experience. A quality mount is thus an essential feature and should not be overlooked when choosing a telescope. Many modern mounts include computerized electronic components that can automatically find and track objects for you. These require extra setup time, a power supply, and some may say relying on a computer to point the telescope is cheating oneself of learning a new skill. On the other hand, a computerized mount can quickly locate many objects that would be difficult to find manually, especially for beginners. If on a budget and looking to maximize light gathering capability, it may be best to avoid the extra expense and complication of a computerized mount and rather allocate your money toward something with a larger aperture.
Pointing a telescope toward an exact spot in the sky can be challenging, particularly at high magnification because such a small portion of the sky is being viewed. Finder scopes make this much much easier. They are small, low-magnification, wide-field secondary scopes which allow an observer to quickly and accurately aim the primary scope at a desired object. The magnification of these finder scopes usually ranges from 6x to 12x, with various apertures available (50 mm is common). Other finders do not magnify at all, but rather use a red dot (projected by an LED onto a small piece of glass) in the field of view. These “red dot finders” are simple and intuitive for aiming at bright objects, but do not perform as well when locating dim deep sky objects compared to a magnifying finder scope. Another downside of red dot finders is that they require a small button cell battery (i.e. a watch battery) which can be a hassle to replace.
With the basics of choosing a telescope covered, below are a few recommendations for quality beginner scopes worth buying in 2021:
Smaller and less expensive
Celestron SkyMaster Giant 15×70 Binoculars. If you aren’t quite ready to dive in and buy a full mounted telescope, these binoculars are a great choice. While specifically designed for astronomy, they perform equally well in the daytime for observing wildlife.
Celestron 21024 FirstScope. If you need a small yet decent-quality scope for a young astronomer (without breaking the bank), the Celestron FirstScope is ideal. With a 3-inch (76 mm) aperture and a stable Dobsonian mount, this reflector will gather lots of light for its size and provide quick and easy viewing at a very affordable price.
Orion StarBlast II 4.5 Equatorial Reflector. The Orion StarBlast is a reflector with an aperture of 4.5 inches (114 mm), which more than doubles its light gathering power compared to the smaller 3-inch scopes. It also comes with two Sirius Plossl eyepieces (25mm and 10mm) as an added bonus. You might also consider the version of this scope which uses a tabletop mount (greater stability and ease of use).
Larger and more expensive
Orion SkyQuest XT6. This classic reflector is oftentimes considered the minimum “serious” telescope. Although less portable than the smaller tabletop scopes, it is much more stable, gathers more light, and has a superior aperture-to-price ratio. Ideal for viewing the moon and planets, it can also be used for deep sky viewing in a location with minimal light pollution.
Orion SkyQuest XT8. This is the ideal telescope for a serious entry-level astronomer. The 8-inch (203 mm) aperture is an excellent value for the price, and the Dobsonian style mount is extremely stable and easy to use. Compared to the XT6, this scope can collect 78% more light due to the additional 2 inches of aperture. It provides brighter and more detailed views of the planets, and allows viewing of fainter nebulas, galaxies, and star clusters which are too faint to see with smaller telescopes.
Zhumell Z8 Delux. This scope is similar to other 8-inch Dobsonians in this price range with some extra perks. The Z8 Delux comes with two eyepieces: a 30 mm wide-field and a 9 mm for higher magnification. These dual eyepieces will provide ideal magnification settings for viewing planets and deep sky objects right out of the box. It also has a dual-speed focuser allowing for very precise focus control.
Our cosmic neighborhood is out there, waiting. Why not get a telescope and begin exploring space from your own backyard? What better way to connect with loved ones than by sharing an awe-inspiring view of the cosmos together. Maybe even host your very own star party!