On a dark night well away from the city, the sky seems to explode with stars. To help orient themselves, ancient skywatchers named the brightest objects-names we still use today. In more modern times, astronomers have cataloged thousands of stars and deep-sky objects, and fixed their positions on a celestial grid.

Scientists have also learned the sizes and distances of most of the objects we observe. Of course, all this knowledge does observers little good if the glow from city lights hides the sky from view. Finding a good viewing site can take some effort, but it's worth it. You'll often find some of the best observing at "star parties" attended by fellow skygazers.

Star Names 4 Astronomical Catalogs 5 Understanding Magnitudes 6 Seeing Color in the Sky 7 Dark Adaptation 8 Averted versus Direct Vision 9 Finding Your Way around the Sky 10 Apparent Sizes and Distances 12 Astronomical Distances 14 ... read full excerpt from Teach Yourself VisualLYTM Astronomy ebook