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Getting started with sky-watching; in time for Halley's comet ... what you need, where to learn more about astronomy.

Stretching for untold ligh years, the starry sky is a wondrous phenomenon accessible to us nearly every night. Yet most of us take it for granted.

During the next few months, however, as Halley's comet makes its once-in-a-life-time appearance, interest in the heavens is bound to soar.

Astronomy--the study of planets, stars, and other heavenly bodies--is the oldest science, and many think the most fascinating. Our report can help you get started in it. And scores of Western amateur astronomy clubs, planetariums, and observatories are offering guidance with special comet-related programs.

What you don't need and what you do

Don't rush out to buy a telescope until you've learned your way around the night sky and you know your astronomical interests. First, spend some nights scanning the sky as the ancients did--with only your eyes. Later, just using good binoculars can give you views undreamed of by Galileo and Edmund Halley.

Prime time for viewing stars, clusters, nebulae, and galaxies is at midnight or later. It's important to find a dark spot; in and around many cities, light pollution is so bad that only the brightest stars can be seen. Moonlight, too, can interfere with some kinds of observing, so new and waning moons are popular periods.

Air turbulence, which also affects viewing, often calms by midnight. After a rain can be a superb time to sky-watch; patchy cloud cover can open to good views.

But much observing can be done even under poor conditions. Small adjustments, like observing from the shadow of a wall, help block out bothersome lights.

Dress warmly and get comfortable. Lie back in a reclining garden chair to ease the strain on your neck.

Allow up to 30 minutes for your eyes to adapt to the dark. (Some people wear sunglasses before going out to observe, to reduce the adaptation time.)

To find the comet or much else, you'll need to know a few key constellations. A simple star chart ($2 to $13) can help. Start by finding the brightest stars, then the constellations. to read a star chart in the dark, you'll need a flashlight; fit translucent red acetate (sold in art supply stores) over the glass to mask the glare.

Helpful books for learning the sky include The Stars: A New Way to See Them, by H.A. Rey (Houghton Mifflin, Boston, 1976; $8.95) and Starwatch: The Best, Most Comprehensive Year-round Viewing Guide, by Ben Mayer (Putnam, New York, 1984; $9.95). Mayer's book tells how to make a fail-safe star finder out of a metal coat hanger, plastic wrap, and typewriting correction fluid.

Many astronomers recommend that you keep pencil and notebook at hand. Enter the date and time of your observations, and try sketching planets or lunar features. This helps you focus your attention and could help you make a contribution to science by documenting such transient objects as comets and variable stars.

Joining an amateur astronomy club

Amateur astronomy is alive and well in the West, as evidenced by the nearly 100 clubs that meet regularly. Always open to visitors, the clubs normally sponsor a monthly business/ lecture meeting, often in a local planetarium or observatory.

Once or twice a month, clubs hold star parties: members meet--preferably miles from city lights--to set up their telescopes for a night of sky-watching. Here you'll find enthusiasts eager to share their telescopic views and show you their specialties, such as astrophotography. Whole families attend, often bringing dinner and sleeping bags. Don't be intimidated, and don't worry about askind "dumb" questions. Any interest you show will be appreciated.

Planetariums and observatories can often tell you how to hook up with a club in your area. Or, for the name and address of the clubs nearest you, write to Don Archer, Astronomical League, Box 12821, Tucson 85732. Include a stamped, self-addressed business-size envelope with your query.

Other sources of help for novices

A readable and useful introduction is Astronomy: A Step-by-Step Guide to the Night Sky, by Storm Dunlop (Macmillan, New York, 1985; $8.95). Two monthly magazines are other sources of information: Astronomy and Sky & Telescope, available at some newsstands and libraries.

The Astronomical Society of the Pacific provides members ($21 annual dues) with a monthly sky calendar and star charts as well as the bimonthly Mercury magazine. for a brochure, write to the society at 1290 24th Ave., San Francisco 94122.

Comet Halley: a celestial "snowball"

Scientists now know that a comet is made of ice and space dust--just a "dirty snowball," as one astronomer noted.

Like a celestial exclamation point, Halley's comet has a head and a tail, as pictured on page 62. The head has a small inner core, or nucleus, of frozen gases and dust encircled by a cloud called a coma. (Halley's nucleus is only 1 to 3 miles in diameter, but its coma is as much as 100,000 miles across.)

The head will first appear as a faint, fuzzy blob. As the comet approaches the sun, solar radiation begins to vaporize the icy core and the coma begins to form. Charged particles called solar winds push the material into sweeping tails (one of gas, one of dust)--"the closest thing to nothing that is still something," quips one astronomer. The tails grow brighter and longer as the comet nears the sun.

Halley's 1985-86 performance won't be as spectacular as its show in 1910, when Earth passed through its tail. This time, the comet will come no closer than 39 million miles, and so it will be considerably dimmer. But with proper viewing conditions, the comet should be visible through binoculars and low-power telescopes this month.

Comet-watching: where you live

will make a difference

If you live near 41[deg.] north latitude--on an east-west line running roughly through Salt Lake City and Eureka, California--the comet will appear just above the southern horizon. The farther south you live, the higher the comet will appear. But because it will often be low in the sky, back-yard views may be blocked by trees or buildings.

For best viewing, head for high deserts or mountains where you'll get clear nights with unobstructed views of the southern horizon. (Some observers, concerned that urban light pollution may prevent a person's one chance to see the comet, have launched a light-dimming program called "Dark Skies for Comet Halley." For details, write to the Astronomical League, Box 12821, Tucson 85732.)

To track the comet, you'll need to locate some celestial reference points--certain bright stars and constellations. Among the guidebooks we've seen, two of the most useful in dealing with Halley's comet are The Comet Handbook, by Garry Stasiuk and Dwight Gruber (Box 12484, Portland 97212; $5.50 postpaid), and Halley's Comet!, by Francis Reddy (AstroMedia, Milwaukee, Wis., 1985; $9.95). Both guides have charts.

Beyond the naked eye:

binoculars or telescope?

Looking at Halley's comet through a high-power telescope could be compared to viewing a Picasso through a drinking straw. Its tail will soon overfill the viewing field of any telescope not suited for widefield observation.

For this reason, many experts recommend binoculars for comet-watching, as well as for observing large bodies such as the moon and the Andromeda galaxy. Binoculars come in various configurations; 7x50s are excellent for hand-held use at night. For more on binoculars, see page 38 of the October 1985 Sunset.

Telescopes are useful for locating the comet early and late in its go-around, and for studying details such as the head. Yet no single telescope is best for all astronomical targets. We show the basic lineup on page 67. A star party can introduce you to a variety of telescopes as well as eyepieces and other accessories.

Cometary calendar

Here's a calendar of Halley's travels through next april:

Novmber. With binoculars or a telescope, look for faint, tailless Halley's comet to rise in the east in the early evening. Best viewing will come about midnight during the first two weeks. On November 10, the comet will pass above the brightest star of the Taurus constellation, then just south of the Pleiades star cluster on November 15 and 16.

On November 127, when the comet enters Pisces constellation, it will be closest to Earth until April 1986, but its distance (58 million miles) and a full moon will hamper viewing.

December. Binoculars will be sufficient as the tail begins to grow. Right after sundown, start observing the comet high in the southern sky. Halley enters Aquarius on December 20; track it in that constellation through Christmas. By month's end, try naked-eye sighting from a dark site.

January. The comet should now look like a tiny star with haze around it and have a small tail. Early in the month, best viewing will be right after sunset in the southwest sky; look above the bright planet Jupiter. By month's end, the comet vanishes in the glare of sunset. (Never attempt to view the sun directly or your eyes could be injured.)

February. Halley will reach perihelion--its closest point to the sun--February 9, but won't be visible. About February 20, start viewing 1 to 1-1/2 hours before sunrise; look for the tail to rise over the southeastern horizon. The tail may extend 5[deg.] or more in length--the equivalent of 10 full moons (the moon is 1/2[deg.] wide as seen from Earth).

March. In early March, the comet will be visible briefly before sunrise low in the southeast sky. Best viewing comes March 15 through 20, when moonlight won't interfere. By month's end, the tail may stretch 20[deg.] or more.

april. Halley should reach maximum brightness. It will be low in the southern morning sky April 5 through 10; Southern Arizona and New Mexico, Southern California, and Hawaii should get excellent views. On April 11, Halley reaches perigee--its closest point to Earth. On April 24, a total lunar eclipse will be visible over the Western states and Pacific Ocean.

through spring, as the comet recedes into space, it will fade until it disappears from the summer sky. Your children or their offspring may see it around 2061.

Comet-viewing at observatories,

shows at planetariums

Throughout the West, planetariums, observatories, and amateur clubs have planned events to welcome Halley and to celebrate astronomy in general.

Many planetariums are dramatizing the comet's return with multi-image shows that recall the comet's legends and explain its behavior. At some observatories, you'll be able to look through powerful telescopes for an eye-popping view of Halley's head or perhaps Jupiter, some 400 million miles away. And amateur astronomy clubs will offer equipment and expertise.
COPYRIGHT 1985 Sunset Publishing Corp.
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Copyright 1985 Gale, Cengage Learning. All rights reserved.

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Date:Nov 1, 1985
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