Читать книгу Astronomy For Dummies - Maran Stephen P. - Страница 4

IN THIS CHAPTER

❯❯ Understanding the observational nature of astronomy

❯❯ Focusing on astronomy’s language of light

❯❯ Weighing in on gravity

❯❯ Recognizing the movements of objects in space

Step outside on a clear night and look at the sky. If you’re a city dweller or live in a cramped suburb, you see dozens, maybe hundreds, of twinkling stars. Depending on the time of the month, you may also see a full Moon and up to five of the eight planets that revolve around the Sun.

A shooting star or “meteor” may appear overhead. What you actually see is the flash of light from a tiny piece of space dust streaking through the upper atmosphere.

Another pinpoint of light moves slowly and steadily across the sky. Is it a space satellite, such as the Hubble Space Telescope, the International Space Station, or just a high-altitude airliner? If you have a pair of binoculars, you may be able to see the difference. Most airliners have running lights, and their shapes may be perceptible.

If you live in the country – on the seashore away from resorts and developments, on the plains, or in the mountains far from any floodlit ski slope – you can see thousands of stars. The Milky Way appears as a beautiful pearly swath across the heavens. What you’re seeing is the cumulative glow from millions of faint stars, individually indistinguishable with the naked eye. At a great observation place, such as Cerro Tololo in the Chilean Andes, you can see even more stars. They hang like brilliant lamps in a coal black sky, often not even twinkling, like in van Gogh’s Starry Night painting.

When you look at the sky, you practice astronomy – you observe the universe that surrounds you and try to make sense of what you see. For thousands of years, everything people knew about the heavens they deduced by simply observing the sky. Almost everything that astronomy deals with

❯❯ Is seen from a distance

❯❯ Is discovered by studying the light that comes to you from objects in space

❯❯ Moves through space under the influence of gravity

This chapter introduces you to these concepts (and more).