Freedman_2007_Ch1 - I magine yourself in the desert on a...

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Unformatted text preview: I magine yourself in the desert on a clear, dark, moon- less night, far from the glare of city lights. As you gaze upward, you see a panorama that no poet’s words can truly describe and that no artist’s brush could truly cap- ture. Literally thousands of stars are scattered from hori- zon to horizon, many of them grouped into a luminous band called the Milky Way (which extends up and down across the middle of this photograph). As you watch, the entire spectacle swings slowly overhead from east to west as the night progresses. For thousands of years people have looked up at the heavens and contemplated the universe. Like our ancestors, we find our thoughts turning to profound questions as we gaze at the stars. How was the universe created? Where did the Earth, Moon, and Sun come from? What are the planets and stars made of? And how do we fit in? What is our place in the cosmic scope of space and time? Wondering about the universe is a key part of what makes us human. Our curiosity, our desire to explore and discover, and, most important, our ability to reason about what we have discov- ered are qualities that distinguish us from other animals. The study of the stars transcends all boundaries of culture, geography, and politics. In a literal sense, astronomy is a universal subject— its subject is the entire universe. 1-1 To understand the universe, astronomers use the laws of physics to construct testable theories and models Astronomy has a rich heritage that dates back to the myths and legends of antiquity. Centuries ago, the heavens were thought to be populated with demons and heroes, gods and goddesses. As- tronomical phenomena were explained as the result of supernat- ural forces and divine intervention. The course of civilization was greatly affected by a profound realization: The universe is comprehensible. This awareness is one of the great gifts to come to us from ancient Greece. Greek as- tronomers discovered that by observing the heavens and carefully reasoning about what they saw, they could learn something about how the universe operates. For example, as we shall see in Chap- ter 3, they measured the size of the Earth and were able to un- derstand and predict eclipses without appealing to supernatural 1 Astronomy and the Universe 1 Learning Goals By reading the sections of this chapter, you will learn 1-1 What distinguishes the methods of science from other human activities 1-2 How exploring other planets provides insight into the origins of the solar system and the nature of our Earth 1-3 Stars have a life cycle—they form, evolve over millions or billions of years, and die 1-4 Stars are grouped into galaxies, which are found throughout the universe 1-5 How astronomers measure the positions and sizes of celestial objects 1-6 How to express very large or very small numbers in convenient notation 1-7 Why astronomers use different units to measure distances in space 1-8 What astronomy can tell us about our place in the universe The night sky as seen from the European Southern Observatory in Chile. (HännesThe night sky as seen from the European Southern Observatory in Chile....
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This note was uploaded on 01/29/2011 for the course SCIN 108 taught by Professor Nestorcastellanos during the Summer '10 term at American Public University.

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Freedman_2007_Ch1 - I magine yourself in the desert on a...

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