The Exoplanet Handbook, Michael Perryman, Cambridge U. Press, New York, 2011. $80.00 (410 pp.). ISBN 978-0-521-76559-6
An encyclopedist’s goal, and an admirable one for any scientist, is to distill a vast and disparate collection of facts and observations into a coherent, encompassing whole. A high point of such efforts was the work of Georges Louis Leclerc, Count of Buffon (1707–88), author of the Histoire naturelle, générale et particulière. Buffon’s thorough, 44-volume synthesis of the 18th-century understanding of the geology and fauna of our planet was influential and widely read. One of the collection’s most remarkable aspects was its groundbreaking scientific account of Earth’s formation.
Now fast-forward to the complex world of today; the thought of codifying all of natural science into 44 volumes is a hopelessly quaint one. But for a scientific subfield, The Exoplanet Handbook, an encyclopedia of extraterrestrial worlds, is a worthy successor to Buffon’s work. Its author, Michael Perryman, who served as scientific leader for the European Space Agency’s highly successful Hipparcos Space Astrometry Mission in the mid 1990s, has written an excellent, startlingly complete snapshot of the current state of knowledge regarding extrasolar planets.
Before the mid 1990s, such a handbook would have been considered something in the realm of science fiction or an occasion for raised eyebrows. That’s because the scientific community had been subjected to regular, spurious claims of the discovery of planets orbiting other stars. Famous examples include announcements starting in 1855 of a planetary companion to 70 Ophiuchi, a binary star system, and inaccurate projections, persisting until the 1970s, that one or possibly two Jupiter-like planets were harbored in Barnard’s Star, a nearby red dwarf.
The first bona fide detection of an extrasolar planet was published in 1989 by astronomer David Latham and four colleagues. Latham’s team used the Doppler radial-velocity technique to sense an object of at least 11 Jupiter masses on an eccentric 83.9-day orbit around HD 114762, a relatively nearby Sun-like star. However, given the poor track record of previous extrasolar planet claims, the discovery of an object orbiting HD 114762 did not generate excitement within the astronomical community.
In 1992 Aleksander Wolszczan and Dale Frail, using extremely accurate pulse-arrival timing methods, detected two terrestrial-mass planets with Mercury-like periods of 66.5 and 98.2 days orbiting the millisecond pulsar PSR 1257+12. That discovery was followed in 1995 by Michel Mayor and Didier Queloz’s discovery of 51 Pegasi b, with a minimum mass roughly half that of Jupiter and a startlingly short 4.23077-day orbital period. Thereafter, the pace of discovery ballooned, as did our understanding of both the planetary census and the physical characteristics of alien worlds.
The Exoplanet Handbook is divided into two distinct segments: The first eight chapters focus on detection methods, and the last seven chapters are devoted to the physical characterization, formation, and evolution of the planets themselves and their host stars. The latter section is quite complete and will be of immediate utility to students or researchers entering the field. The first section is a thorough, authoritative, and evenhanded discussion that heightened my appreciation of the current detection-method landscape. It’s remarkable that so many methods—including Doppler velocity, transit photometry, astrometry, pulse timing, gravitational microlensing, and direct imaging—have all successfully detected extrasolar planets in the past two decades. Together, those methods have enabled the discovery of nearly 800 well-characterized extrasolar planets; thousands more have been pinpointed by photometric monitoring with NASA’s Kepler spacecraft.
Like any good encyclopedia, The Exoplanet Handbook has as its major strength its reference list, which cites more than 4000 papers. The list provides a near-complete snapshot of all the research that has taken place in the field in the past two decades. Furthermore, the references are deftly integrated into the text, which makes this volume an excellent point of departure for any researcher seeking to chart a new course of exoplanetary investigation.
Gregory Laughlin is chair of the astronomy and astrophysics department at the University of California, Santa Cruz. His research interests focus on the detection and characterization of extrasolar planets. He writes regularly at http://www.oklo.org about his work and about developments in the field.
