Thousands of years ago, people looked at the sky in wonder, fascinated by the motions of a few wandering “stars.” Nobody understood where these wandering objectsnow named Mercury, Venus, Mars, Jupiter, and Saturncame from, why they moved, or what drove their motions through the sky. Today, people know these objects are planets, but the quest to reach this understanding took thousands of years, and the consequences were profound. Famous scientists Johannes Kepler, Edmund Halley, Isaac Newton, and others discovered the laws of gravity and planetary motion, using these laws to explain the workings of the solar system. Their findings allowed the human race to find its way from planet to planet with unmanned probes and eventually allowed people to reach the moon. In Planetary Motion, learn how scientists have found new planets outside the solar system, and continue their search for planets like Earth.
Full-color photographs and illustrations. Sidebars. Further reading. Web sites. References. Glossary. Index.
About the Author(s)
P. Andrew Karam, Ph.D., is a scientist, writer, and educator with a Ph.D. in environmental sciences. He has written more than 100 technical articles and editorials in scientific and technical journals and newsletters, and has authored more than 200 encyclopedia articles and several books.
Ben P. Stein is a professional science writer and worked at the American Institute of Physics for 16 years. His writing has appeared in Encyclopedia Britannica, Popular Science, New Scientist, Salon, and many other publications.