Binoculars

To get into astronomy you need a telescope, right? Well, maybe. Most amateur astronomers eventually get a telescope? Some acquire more than one through the years. However, many astronomers also regularly use binoculars as well. With a pair of binoculars you can see many star clusters, such as the Pleiades, the Double Cluster in Perseus, the Hercules Cluster, etc. You can also see many nebulas, such as Orion, the Dumbbell, etc. Galaxies can be viewed as well. The Andromeda Galaxy is easily viewed with binoculars. While binoculars won't show you planetary detail, or the faint detail of many of these deep sky objects, their easy of use and small size makes them a great addition to any astronomers toolkit! Binoculars will also show you some things which most telescopes are unable to show, namely, very large fields of view. While a wide angle telescope might show you 2 or perhaps 3 degrees of the sky, binoculars typically show at least 5 degrees. Some wide angle binoculars will show you 7 degrees! This wide angle viewing capability is great for locating objects, as you can cover huge chunks of the sky quickly.

Ok, you're convinced. So.. what size should you get? 10x50 binoculars are probably the most commonly used size in astronomy. They bring in quite a bit more than the typical 7x35 without much additional bulk. They are also relatively easy to hold steady when viewing overhead. You may be wondering "What does 10x50 mean?" Well, the first number refers to the amount of magnification provided. In this case 10. That means that the object being viewed appears 10 times larger than when viewed without binoculars. The second number refers to the size of the lens, 50mm in this case. As a point of reference, the average person's pupil dilates to about 6 or 7mm when fully dark adapted. Incidentally, light gathering capability corresponds to the square of the aperture. So, a pair of 10x50 binoculars provides 10 times the magnification and 50 to 60 times the light gathering power of your eyes. This is a substantial increase.
Moving up in size, you'll typically find binoculars up to about 30x magnification and 70 or 80mm in diameter. Some specialty binoculars can even be purchased that are over 100mm in diameter. This is like looking through 2 telescopes!
And speaking of 2. Many people are able to pull in much more detail when viewing with both eyes as opposed to only 1. So, a pair of binoculars could very well be your ticket to the universe.

The Astronomer's Standard: 10x50 Binoculars