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Finding your way: here's how to use our monthly sky charts to identify the evening stars and constellations.


CAN YOU SPOT THE BIG DIPPER? Orion? The Pleiades? The first step into amateur astronomy is learning the stars in your evening sky. Once you know them, they'll be your companions for life.

Starting on the next page are 12 sky maps, one for each month of 2010. Accompanying each chart is a look at some of the constellations, stars, deep-sky objects, and planets visible during the month. And the CD-ROM that's packaged with SkyWatch 2010 includes charts for the last two months of 2009, plus even more detailed information from Sky & Telescope, our monthly magazine.

Getting Oriented

Start by finding the map for the current month. Check the dates and times printed at the top of the page. Take the chart out under the night sky within an hour or so of these times. Bring along a red-light flashlight by which to read it; the dim red light won't ruin your night vision.


Outside, you need to know which direction you're facing. (If you're unsure, note where the Sun sets--that's roughly west.) Turn the map around so the yellow label along the edge matching the direction you're facing is right-side up. The curved edge represents the horizon, and the stars above it on the map now match the stars in front of you. The farther up from the map's edge they appear, the higher up they'll be in the sky. The center of the map is the zenith, directly overhead.

The Moon is plotted at its location when full and at selected other phases leading up to full. The planets are shown where they'll be at midmonth.

At the lower left of each chart is a scale depicting the magnitude (brightness) of the stars. Higher numbers mean fainter stars: a 1st-magnitude star is about 2.5 times brighter than one of 2nd magnitude. The chart shows stars as faint as 4th magnitude--about as dim as you can see with the naked eye through suburban light pollution.

Into the Night

Let's try this with the map on the next page, the one for January 2010. Turn it around and hold it so that its southeast horizon (labeled "Facing SE") is right-side up. About halfway from there to the zenith is the constellation Orion, with bright reddish Betelgeuse for his shoulder, blue-white Rigel for his foot, and his famous three-star belt between. Go outside at the right time, face southeast, look halfway up the sky, and there's Orion!

The sky maps and twilight scenes are drawn for an observer near 40[degrees] north latitude (for example New York or Denver) but can be used throughout the continent. If you're south of 40[degrees], stars in the southern part of the sky will appear higher than the map shows, and stars in the north will be lower. If you're north of there, the reverse is true. Don't worry about time zones; the hours are for your local time.

European skywatchers can also use the maps and scenes, though the Moon in the twilight scenes will be displaced a quarter of the way toward the Moon symbol for the preceding date.

Greek Letters on Star Maps

The brightest stars in each constellation are named with Greek letters. A constellation's most brilliant star is often called Alpha, the first letter in the Greek alphabet.

[alpha] Alpha

[beta] Beta

[gamma] Gamma

[delta] Delta

[epsilon] Epsilon

[zeta] Zeta

[eta] Eta

[theta] Theta

[iota] Iota

[kappa] Kappa

[lambda] Lambda

[mu] Mu

[nu] Nu

[xi] Xi

[omicron] Omicron

[pi] Pi

[rho] Rho

[sigma] Sigma

[tau] Tau

[upsilon] Upsilon

[phi] Phi

[chi] Chi

[psi] Psi

[omega] Omega
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Title Annotation:How To Use the Sky Maps
Author:Schaaf, Fred; MacRobert, Alan
Geographic Code:1USA
Date:Jan 1, 2010
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