Hobbies & Leisure
Stargazing
published by Barnes & Noble
Know what’s out there. Like a great work of art, the night sky is even more fascinating if you’re able to appreciate the features within it. So step outside and demystify the universe—one tiny speck of light at a time—with this all-encompassing guide to: • Basic tools and techniques you’ll need for effective stargazing • Stars, planets, and galaxies you can see through binoculars or a telescope • Special astronomical events—meteor showers, eclipses, comets, and more
What Is Stargazing? Stargazing means a whole range of things: simply watching the night sky, identifying celestial objects (such as stars, planets, and distant galaxies), understanding and predicting their motions, and appreciating their beauty. Some people stargaze out of interest in the science of astronomy, some seek the challenge of locating faint and distant objects, and others enjoy sensing the vastness of space and their own place in the universe. All you have to do to stargaze is step outside, look up at the night sky, and start asking questions: Where do the stars rise and set? What constellations can I see? Are all stars white, or do they have different colors? How can I tell a star from a planet? The more you learn and practice, the more rewarding your experience will be.
How to Get Oriented in the Night Sky You don’t need to be on a remote mountaintop with a fancy telescope to enjoy stargazing. These five steps will help you get started anywhere with just your naked eye:
1. Know Where You Are What you can see in the night sky depends on where you are on Earth. If you’re in Seattle, for example, you can see the Big Dipper circle slowly above you in the sky at any time of the night, at any time of the year. In Miami, however, the Big Dipper rises in the northeast and sets in the northwest during the summer, and can’t be seen at all in the winter. This is because latitude—how far north or south you are—affects what stars you see. (On the other hand, longitude—how far east or west you are—does not.) You can find your latitude on a map or look it up online. It’s also important to know which way is north so you can get your bearings in the sky. If you’re not sure what direction you’re facing, look at a compass or remember that the Sun will have set in the west. With practice, you’ll be able to find north just by looking at the stars.
2. Look Up When you go outside, always wait a minute for your eyes to adapt to the dark before you get started—this will help you see fainter stars. Look at the ground for a few minutes until you feel adjusted, and avoid looking at streetlights or headlights or using flashlights while you stargaze.
• Zenith and nadir: In stargazing terms, the highest point in the sky directly above you is called the zenith, and the point directly below you (under your feet) is called the nadir. It’s important to note that, unless you’re standing at exactly the North or South Pole, the sky does not rotate precisely around the zenith. • Stars vs. planets: At first, the night sky may look vast and intimidating, with what seems like an infinite number of stars. The human eye, however, can see only about 6,000 stars, even in the best observing conditions. The first objects you’ll see are the brightest ones—and these are often planets, not stars. A good way to tell planets from stars is with the “twinkle test”: stars twinkle, whereas planets appear to shine steadily.
The Big Dipper and Little Dipper The Big Dipper is one of the brightest and easiest asterisms, or clusters of stars, to spot in the night sky. (It’s not technically a constellation, as it makes up only part of the full constellation Ursa Major.) Four stars make up the Big Dipper’s “bowl,” and another three make up its “handle.” The two stars at the end of the Big Dipper’s bowl are pointers—if you join these with an imaginary line and extend that line from the bottom of the bowl upward, you find the North Star. Or, if you can spot the less bright Little Dipper, which has the same shape as the Big Dipper but is upside-down, you can also find the North Star at the end of its handle. Big Dipper
3. Find the North Star The North Star, or Polaris, is a good first star to identify— it’s the only star that’s always in the same spot in the sky, no matter what time of night or time of year. There are two ways to find it:
Polaris Mizar
The Hand Scale The North Star is always straight above the north horizon, and its height in the sky is the same as your latitude. For example, in Phoenix (latitude 33°N), the North Star is 33° above the horizon looking due north.
1°
30°
Alcor
Little Dipper
4. Know How the Sky Moves The motion of the night sky is caused by the Earth rotating west to east on its axis, an imaginary line between the north and south poles. The Sun, Moon, stars, and planets all seem to rise in the east and set in the west due to this rotation.
The Celestial Sphere
20°
north celestial pole
zenith
10°
If you hold your arm out straight, you can use your hand as an approximate scale to measure degrees in the sky: a clenched fist is 10°, and the width of an index finger is 1°. Start with the bottom of one fist lined up with the north horizon then stack your other fist on top, then move your bottom fist on top of that one, counting 10° with each fist. In Phoenix, for example, if you stack three fists and count 30°, then stack three index fingers to reach 33°, the North Star should be right above your top finger.
cel est ial
horizon equ ator
To help visualize these motions in the sky, stargazers imagine the Earth at the center of a giant spinning celestial sphere that’s covered with all the stars. If you extend the Earth’s axis from the north pole until it hits the celestial