Much has been written in this book on how to find bright stars and constellations, observe meteor showers, and other cyclical sky phenomena. But almost no mention has been made about the objects that garner some of the greatest interest among skywatchers: the planets. That's not to say that the planets aren't always in the sky, because they are. However, they aren't always in the same part of the sky year after year. That's the tricky part.

The planets were known as ‘wanderers’ to ancient astronomers because that's exactly what they appear to do: wander back and forth among the constellations of the ecliptic, or zodiac. No naked-eye planet stays in one region of the ecliptic forever because the planets, like Earth, are in orbit around the Sun. As each planet traces out its varied orbit, it shifts nightly with respect to the distant background stars. Planetary orbits are well established, however, allowing their future positions to be easily plotted. You can obtain these positions from the various sky almanacs listed in the bibliography, or from astronomy software programs like Voyager, The Sky, and Starry Night. (These and other ephemeris programs are available from most companies offering books and software for amateur astronomers. Some primary vendors are Sky Publishing Corporation, P.O. Box 9111, Belmont, Massachusetts 02178-9111, (www.skypub.com/); the Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California, 94112 (www.aspsky.org); and Orion Telescopes and Binoculars, P.O. Box 1815, Santa Cruz, California 95061 (www.oriontel.com).