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        PATTERNS OF STARS

        Groups of galaxies are held together by gravity in clusters
        (Figure 1-2h), and clusters of galaxies are held together by
        gravity in superclusters. Huge quantities of intergalactic gas
        are often found between galaxies (Figure 1-2i).
        Every object in astronomy is constantly changing—
        each has an origin, an active period you might consider as
        its “life,” and each will have an end. We will study these
        processes along with the important physical concepts upon
        which they are based. You will also discover that all the
        matter astronomers see in stars and galaxies is but the tip of
        the cosmic iceberg—there is much more in the universe, but
        astronomers do not yet know its nature.
        PATTERNS OF STARS
        When you gaze at the sky on a clear, dark night where the
        air is free of pollution and there is not too much light, there
        seem to be millions of stars twinkling overhead. In reality,
        ... Detalii... »

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        NEW FEATURES BRING THE UNIVERSE INTO CLEARER FOCUS

        Scientifi c American articles, chosen by the author, are included
        in the text to illuminate the core concepts in the text.
        These brief, recent, and relevant selections demonstrate

        the process of science and discovery, while also providing touchstones for classroom discussion.
        A new chapter on astrobiology provides students with a thorough overview of this motivating and exciting area of astronomy, correcting common misconceptions and illustrating
        the ongoing development of our scientifi c knowledge.
        Focus questions about important concepts are presented in
        most sections of the book.

        These questions encourage students to test themselves frequently on material presented in the preceding sections of the chapters and thereby correct their beliefs before errors accumulate. For example, after learning about

        Uranus’s ring system in Section 5-29, students are asked why Uranus’s ri ... Detalii... »

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