MIRROR EARTH

The discovery of planets beyond our solar system has become almost commonplace. Veteran Time science writer Lemonick (Echo of the Big Bang, 2003, etc.) looks at the scientists who carry out the search.

The author begins with a brief look at the time before planets had been found orbiting other stars. Astronomers thought such planets probably existed, but finding them entailed very precise measurements of the wobble caused by a body in orbit around a star or the dimming of light as it passed between the star and the observer. Attempts were made as far back as the 1960s, but it took until 1995 for Swiss astronomers Michel Mayor and Didier Queloz to make the first discovery, a body half the size of Jupiter orbiting the star 51 Pegasi every four days. This "hot Jupiter" confounded existing theories of planet formation, which assumed our solar system was somehow "typical." But when Geoff Marcy and Paul Butler of San Francisco State University found two more planets in observations they had been recording for six years, the game was on. New tools, notably space telescopes, made the task easier; so did the arrival of a generation of astronomers whose imaginations were fired by this grand new enterprise. Lemonick gives profiles of a number of these "exoplaneteers": Canadians Dave Charbonneau and Sara Seager, who learned their trade at Harvard; and Debra Fischer and Natalie Batalha of the University of California. Also central to the story is Bill Borucki, the driving force behind the Kepler space telescope. The chase is now focused on finding planets close to Earth in size. Do any of them have the conditions under which life could have arisen? That remains to be seen, but Lemonick makes it clear that the exoplaneteers are busily working to find ways to detect them.

A solid overview of the cutting edge of astronomy and of the new breed of astronomers who are exploring it.