Want to start observing the night sky? You might be dreaming about getting a telescope, but there is a simpler and cheaper way to start - binoculars. They don't have the high magnifications of telescopes, but binoculars are portable and let you scan large areas of sky at a time.
In 1610 Galileo discovered wonders such as the craters on the Moon, the satellites of Jupiter and the phases of Venus. He did all this with a telescope that was optically inferior to even the cheapest binoculars you can buy today. So there is more you can do with binoculars than you might at first realize. Better still, you might even have a pair of binoculars in the house already, for sports or leisure viewing. These work just as well for astronomy!
Binoculars are like two little telescopes joined together. They have prisms in them to fold the light beam, which makes them shorter than telescopes and accounts for their dog-leg shape.
Look at the top of the binoculars and you will see numbers such as 6 x 30, 8 x 40, or 10 x 50. The first figure is the magnification, and the second is the width of the main lenses, in millimetres. This means that a pair of 8 x 40 binoculars magnifies 8 times and has lenses 40 mm wide (just over one and a half inches).
Larger lenses collect more light so they will show fainter objects. However, the binoculars will be heavier and more awkward to hold. If you are choosing binoculars for a child, 8 x 40 is probably big enough. If you cannot hold the binoculars steadily you will not see much!
Zoom binoculars are available which give a range of magnifications, but these are significantly more expensive. Yet be sure to avoid cheap binoculars with very high magnifications such as 20 times. These give a faint and usually poor-quality image with a very limited field of view.
To get the most out of your binoculars, you'll need to adjust them to suit your own eyes. The two halves are joined by a bar which can be pivoted until the distance between the eyepieces is the same as your eyes. Most binoculars have a central knob for quick focusing, while one eyepiece can be individually adjusted to compensate for differences between each eye. Binoculars in which each eyepiece has to be adjusted individually are inconvenient to use.
What to see?
What can you see with binoculars? Firstly, they cut through light pollution in urban areas, allowing you to see faint stars, nebulae, and galaxies that are normally beyond view. Sweep along the band of the Milky Way and you will see sparkling masses of stars, just as Galileo did over 400 years ago.
If it's winter, take a look at Orion's sword hanging beneath his belt. Here you will see the misty patch of the Orion Nebula, an area where stars are still being born. In neighbouring Taurus are the star clusters called the Hyades and Pleiades. The V-shaped Hyades marks the face of the bull, while the Pleiades, popularly known as the Seven Sisters, is a sparkling clutch of dozens of new-born stars.
In the constellation Andromeda you will be able to find the ghostly smudge of the Andromeda Galaxy, M31, the nearest large galaxy to us, a staggering 2.5 million light years away.
Closer to home, when you look at the planet Jupiter you will see that it is not a point of light like the stars, but has a small disk. Wedge the binoculars steadily and you will see up to four specks of light either side of it which change position from night to night. These are Jupiter's four main moons, orbiting the planet.
When a new comet sweeps into view, binoculars are the instrument of choice for observing its fuzzy head and flowing tail.
Perhaps the most spectacular views are of the surface of the Moon. Large dark lava plains and jagged craters spring into view. (Click on the link below the article for more information about observing the Moon.)
One very important word of caution, though. While it is safe to look at the Moon at any time, that most emphatically does not apply to the Sun. Never, ever look directly at the Sun with any form of optical equipment, as you will risk burning your eye, causing partial or total blindness. Even staring at the Sun for long periods can damage your sight.
Later on you might get a telescope, but you'll still need binoculars for general viewing. Don't look down on the humble binocular!