Pictures in the stars
Get up early, before the sun rises. Look at the sky to the east. Weather permitting, you'll see him. At this time of year, he's just getting up, too. His name is Orion, and he's the biggest hunter the world has ever seen. Each night, he moves across the sky, hunting.
But he doesn't hunt anywhere on Earth. He's a constellation. People have been looking at the "Hunter" for thousands of years.
Welcome to astronomy.
From ancient times, when people looked at the night sky, they imagined they could draw lines connecting neighboring stars. Today, we call these sky-pictures "constellations."
A constellation is a collection of stars visible to the naked eye. When you look at a group of stars in a certain way, they form a shape. This is how the earliest people looked at the sky. They might have climbed a mountain, or they might have just looked up while lying on their backs. They didn't have telescopes. They certainly didn't have the Hubble Space Telescope looking deep into the heavens from above the Earth's atmosphere.
If you do get up early, the best way to find Orion is to look for his belt. It is made from a straight row of three stars. You can't miss his belt if it's a clear sky and you're not in the center of a big city where artificial lights block out the stars. These three stars in Orion's belt and the Big Dipper are the best-known stars in the northern skies.
After you find his belt, look up and to the left. Imagine that he is facing you. Can you make out the large club in his right hand? Now look to the right. Do you see the big shield in his left hand?
Look for Orion each night at the same time. You'll notice that he's moving in a southerly direction. It's as though he's taking one step at a time, stalking his prey. He does this every year in fall, winter, and early spring.
By December, he'll be standing straight up in the southern sky. You'll be able to step out in the backyard after dinner and see him. This is because the earth is moving in its orbit around the sun, changing your viewing position. (The stars in the constellations are all moving, too, but you can't tell. You'd have to observe a star for thousands of years to notice that it has moved.)
As spring arrives, Orion drops below the horizon. He's still there, but the seasonal tilt of the earth on its axis blocks him from view for those of us in the Northern Hemisphere.
What you see when you look up at the night sky depends on four things: the time of year (the position of Earth in its orbit around the sun), the time of day or night, your location (people in Boston see a different sky at 10 p.m. than do people in Sydney, Australia at 10 p.m.), and atmospheric conditions. Is it clear or cloudy? Are you out in the country or near a big city with lots of artificial lights dimming the stars?
Cold winter nights can be clearer than humid summer nights. (Humid air tends to scatter starlight.) Be sure to dress warmly.
Some of the constellations people have seen for centuries are patterns that look like people: Orion, Hercules, Perseus, Andromeda. Other patterns look like animals: Taurus the bull and Ursa Major and Ursa Minor (the big and little bears). Those last two constellations include two constellations you're no doubt familiar with: the Big Dipper and the Little Dipper.
It all depends on how you draw the lines between the stars!
It seems there are as many astronomy-related websites as there are stars in the sky. Here are a few to get you started.
www.spacekids.com
This site has lots of interesting features including: games, news, movies, and photos.
www.earthsky.com/Features/ Skywatching/
This site has a tip on what's most interesting and visible to the naked eye each night. The information is presented one month at a time.
www.nasa.gov/kids.html
NASA for kids is run by the US space agency.
www.stsci.edu/top.html
Images taken by the Hubble Space Telescope. Click here for some of the coolest pictures on the Internet.
BOOKS
Many are available. I'll just mention two:
"The Audubon Society Field Guide to the Night Sky," by Mark R. Chartrand (Knopf, 1991). Like Audubon's bird-watching guides, it's authoritative, has great pictures, and fits in your pocket or backpack.
"Turn Left at Orion: A Hundred Night Sky Objects to See in a Small Telescope - and How to Find Them," by Guy Consolmagno and Dan Davis (Cambridge University Press, 1989). If you really get hooked on stars, and want to go to the next level - using a small telescope - this book is what you're looking for.
My favorite is "Starry Night," by SPACE.com. It comes in three versions: beginner ($29.95), intermediate ($49.95), and advanced ($129.95). You can download a free 15-day trial offer of the intermediate version at www.space.com.
You can also download free star-tracking software that is not as sophisticated (but hey, it's free) at this site: www.stargazing.net/AstroTips/english/index.html
