Robert Sanders, UC Berkeley Media Relations
(510) 643-6998,
Tina McDowell, Carnegie Institution of Washington
(202) 939-1120,

Berkeley — The National Academy of Sciences announced yesterday (Wednesday, Jan. 10) that the world’s most successful planet hunters, Geoffrey Marcy of the University of California, Berkeley, and Paul Butler of the Carnegie Institution of Washington, will be awarded the prestigious Henry Draper Medal on April 30 during the academy’s 138th meeting.
The academy awards the Draper Medal every four years to individuals who have made a significant contribution to astronomical physics. It was established through the Draper Fund and first was awarded in 1886.
Butler and Marcy were cited by the academy "for their pioneering investigations of planets orbiting other stars via high-precision radial velocities." They will join the ranks of other noted astronomers including George Ellery Hale, Arthur Eddington, Harlow Shapley, Horace Babcock, and the team of Arno Penzias and Robert Wilson.
A decade ago, finding planets orbiting other stars was the stuff of science fiction. But that has changed. Since 1995, Marcy, Butler and their colleagues have discovered 38 of the 53 known extrasolar planets. Their joint finds include the only planet thus far observed to transit a host star, two sub-Saturn mass planets and, announced earlier this week, a multiple-planet system that may alter our current definition of the term planet.
The celestial detectives are leaders of a team engaged in a multi-year research project to look for planets around 1,100 stars that are within 300 light-years of Earth. Some of the planets they have thus far detected have challenged existing theories on planetary formation.
Marcy, a professor of astronomy in the College of Letters & Science at UC Berkeley, and Butler together conceived a novel technique for measuring stellar Doppler velocities, the telltale wobbles indicating an orbiting planet. From these measurements, they were able to deduce the mass and orbit of companion planets. After some eight years of hard work, they announced their first planet discoveries in 1995, shortly after a Swiss team reported the first tentative detection of an extrasolar planet. Since then, Marcy, Butler and their colleagues have continued observations at the Lick Observatory at UC Santa Cruz and have extended their planet search to the more sensitive Keck telescopes operated in Hawaii by a consortium of the University of California and Caltech. To view stars in the Southern Hemisphere, the team uses the Anglo-Australian Observatories and will use
Carnegie’s Magellan telescopes in Chile as they become operational.
Butler’s work focuses on improving the precision of Doppler velocity measurements. He designed and built the iodine absorption cell system at Lick, resulting in the discovery of six of the first eight extrasolar planets. This instrument is now the standard for precision Doppler studies.
By 2010, the team hopes to have completed a "planetary census" of nearby stars. They will be able to tell what percentage of stars have planets, how many planetary systems are like our solar system, and how many types of planetary systems exist.
Their work is supported by the National Aeronautics and Space Administration, the National Science Foundation and Sun Microsystems. Other team members include post-doctoral researcher Debra Fischer of UC Berkeley and astronomy professor Steve Vogt of UC Santa Cruz.
The Carnegie Institution, founded by Andrew Carnegie in 1902, is a private, nonprofit organization engaged in basic research and advanced education in biology, astronomy and earth science.
* National Academy of Sciences
* Keck Observatory
* Lick Observatory
* College of Letters & Science
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