A Word about Binoculars

Probably the most cost-effective accessory for the beginner are binoculars. Good quality binoculars can be purchased at the same cost as a cheap, low quality telescope. Binoculars can also be useful for Mum and Dad, especially if their budding junior astronomer loses interest. They can at least be used for more terrestrial pursuits. Such an investment can be a cheap way of gauging their level of dedication. This does not mean we are suggesting the quality of the binoculars should be poor. It is recommended that even binoculars should be purchased from a reputable optics or telescope dealer. They are people who appreciate the quality required for stargazing. Astronomy is indeed a severe test on optics. Such shops can also assist with mounts to hold the binoculars steady. These are often brackets designed to attach to a tripod (sorry, another possible expense). To observe details on the Moon or looking for Jupiter's moons, it is recommended that binoculars are not hand held. Sometimes you can brace yourself on the arms of a chair or the roof of a car. This can be important if the power of the binoculars is more than 10X. A power of 7X is considered a reasonable compromise. It can give a good field of view with adequate magnification to glimpse some of the inner moons of Jupiter. The size of the aperture normally comes down to what is comfortable for the person to hand hold and the budget. 7X50 binoculars (7 times magnification, 50mm diameter front lens) are fairly popular with amateurs.

There are a multitude of uses for binoculars in amateur astronomy. Some of these include:

• Helping to find stars and planets in the bright twilight sky.
• Looking at the craters and rays on the Moon.
• Looking for fainter stars marked in star atlases or on the Sky Views and finder charts in our yearbook. This can be important in bright, light polluted skies.
• Looking for stars dimmed by the nearby Moon.
• The colours of the stars and planets are more obvious through binoculars. Check out the red colour of Mars, Aldebaran, Betelgeuse and Antares. Also, the contrast between the yellow of Alpha Centauri and the blue of Beta Centauri is interesting.
• The crescent phases of Venus.
• Stars and planets close to the horizon.
• Looking for Earth satellites in the early evening sky.
• Monitoring the change in magnitude of some of the brighter variable stars. There are also a number of organisations that can help with finder charts and predictions. Start with your local astronomical society.
• Observing the moons of Jupiter as they oscillate across the planet from night to night. It is also possible to observe an occasional eclipse disappearance or reappearance for one of the outer satellites as the moon passes into or out of the shadow of the planet.
• Lunar occultations of some of the brighter stars. Probably small binoculars are best suited for magnitude 4 or brighter events, preferably on a dark limb.
• Looking for bright comets (from dark skies).
• Some of the bright deep sky objects such as the star clusters, Milky Way regions and the Magellanic Clouds.
• Looking for some of the brighter minor planets near opposition. A good exercise is to sketch the field a couple of times a few days apart and see which 'star' has moved.
• Searching out Uranus and Neptune.

Most of the above can be done from a typical suburban back yard. It is not necessary to drive for an hour to reach dark skies. Also scanning the skies for satellites can open up a whole new Universe of discovery as various star clusters and nebulae drift through your field of view.

Finally, it is worth remembering that a pair of binoculars is prone to dewing just like a refracting telescope. A couple of cardboard tubes on the front, sticking out about 75mm, can prevent dew and also help eliminate stray light.