Binoculars are very useful for astronomical observing, and many people already have them to use for watching sports and nature observing. There are dozens of interesting things you can see in the dark night sky with binocs -- the elliptical shape of our sister galaxy, the Andromeda Galaxy, the star clouds of the Milky Way, and the "jewel boxes" of pretty open clusters, to name a few. (Naturally, you have to be outside the city lights to see these.)
Binoculars come in many sizes, kinds, and qualities. For example, some of the more expensive ones use a "straight-through" prism design to make the instrument more compact. For astronomical observing another factor is more important. Binoculars are labeled with a pair of numbers like 7 X 35. The first number is the magnifying power. A power of 7 or 8 is about the maximum you can hold stably in you hands, so this pretty well determines the power to choose. The second number is the diameter of the primary lens in millimeters (mm). For night observing this number should be at least 5 times the first number*; typical binocs are 7 X 35, 8 X 40, and 10 X 50. If you are younger than 40 - 50 years old, the second number should be 7 times the first number. Professional observers recommend 7 X 50. The smaller binoculars that you commonly see nowadays like 7 X 20, 8 X 24, 10 X 27, where the ratio of the numbers is about 3, are fine for daylight viewing, but do not show bright images of the night sky.
My personal choice is 7 X 35, extra wide angle. The "extra wide angle" feature allows you to see more of the sky at the same power, although the star images may not be quite as sharp. You can still hold 10 X 50's in you hands, but it helps if you brace your elbows, or lie back in a lawn chair. Lawn chairs are also good with "giant binoculars" like 9 X 60 and 11 X 80.
The best views I have ever seen were with Fujinon's 16 X 70's. These, however, cost over $600 and need to be used on a tripod, or well braced in a lawn chair. Astronomical companies sell special mounts that hold the binocs pointed in the same direction while you change the height for different sized people to look.
Here are some first objects to look at with binocs.
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