BINOCULARS BEST FOR BEGINNING BACKYARD ASTRONOMY

by Terence Dickinson
SkyNews Editor

You don't have to own a telescope to be an amateur astronomer. Binoculars will reveal an amazing variety of cosmic sights. In my opinion, a good binocular is a better first instrument for the budding backyard astronomer than the so-called beginner's telescopes that appear every year about two months before Christmas in big-box discount stores. Binoculars are easier to use, provide bright, right-side-up images, and have a range of other applications besides astronomy.

Any size and type of binoculars will get you started, but the precise optics in better quality models produce images of celestial objects that are brighter and sharper than cheaper models of the same size. There is usually a good reason why one binocular is three times the price of another even though they look the same on the outside.

A popular size binocular is 8x40, which means a magnification of 8 times and main lenses 40mm in diameter. The minimum for celestial observation is 7 magnification, usually written 7x, and 30mm lenses. Maximum is 10x and 56mm lenses. You would think that the more power the better, but more magnification of the image also means more magnification of the quivers and shakes of your arms as you hold the binoculars to your eyes. I consider 10x the practical limit.

Similarly, bigger main lenses are a good thing because larger lenses mean more light is collected, which means a brighter image - a particularly important advantage in astronomy. But bigger lenses also mean bigger binoculars and more weight. In my opinion, 56mm is the limit for handheld glasses. This is why the only optical product sold by SkyNews is 8x56 binoculars, which I think is the ideal size for backyard astronomy. Other sizes frequently used in astronomy are 7x50, 10x50 and 8x42.

An essential binocular accessory for astronomy is an adapter for attaching the glasses to a camera tripod. One type of adapter (about $12) is L-shaped with a bolt at the top of the L that screws into a threaded hole at the front of the binocular's focusing bar. The base of the L attaches to the tripod like the base of a camera. When buying new binoculars, ensure that they have the threaded receptacle, not all do. If you already own a binocular without the threaded hole, a clamp tripod adapter is available for about $20. The difference in image clarity between hand-held and tripod-mounted binoculars is especially striking at night.

What celestial sights can binoculars show? Here's an abbreviated list:

- Fantastic detail on the moon, including at least 100 craters, mountain ranges and flat plains that seventeenth-century astronomers thought were seas.

- Countless thousands of stars in the Milky Way that are invisible to the unaided eye. This is a good time of year to see the Milky Way if you can get well away from city lights.

- Star colors become more evident with binoculars than without. Besides plain old white, stars range from sapphire blue to yellow, orange and red.

- From two to four of the large moons of Jupiter can be seen close beside the brilliant planet. (Jupiter is that bright object in the southwest during autumn evenings.)

- The planets Uranus and Neptune, which are too dim to be seen with unaided eyes.
The Andromeda Galaxy, a huge city of stars larger than our entire Milky Way Galaxy, is plainly seen as an oval smudge high in the east around midnight at this time of year.

- Star clusters of exquisite beauty, such as the Pleiades and Hyades, are seen in their entirety in binoculars whereas most telescopes (due to their smaller fields of view) can show only portions of them.

All backyard astronomers have binoculars whether or not they own a telescope. They are essential equipment.

CELESTIAL OBSERVING TIPS, AUGUST 2007

by Todd Carlson
SkyNews Assistant Editor

On August 21 the Moon will be one degree below Antares and six degrees below Jupiter. Antares, the brightest star in the constellation Scorpius, translates as "rival of Mars" and glows a fiery red colour. Jupiter, the largest planet in our solar system, appears as a bright creamy-white star and is brighter than any other object in that part of the sky (other than the Moon).

A total eclipse of the Moon will occur in the early morning hours of August 28 when the Moon will be dimmed to less than one one-thousandth of its normal brightness as it passes through the Earth's shadow. Observers in Alberta and British Columbia will have the best seats in the house as they will see the entire eclipse in a dark sky. From Manitoba and Saskatchewan, dawn begins during totality. Areas further east will see the Moon set during totality. The eclipse is visible without optical aid, though binoculars offer enhanced views of the coppery colour of the shadowed Moon. For more detail, see the July/August SkyNews, or www.skynews.ca.