My grandparents met in the Panama Canal Zone. There, Sylvain Misrahi and Pearl Sper (on my father’s side) and Saul Moishe (Martin) Isaacs and Ethyl Hiller (on my mother’s) gave birth to their only children, Robert Misrahi and Gloria Isaacs, respectively, my parents. Both families encouraged education, music, and sports, all of which filled my childhood in the Los Angeles suburbs of the San Fernando Valley during the 1960’s.
My mother and father, with college educations in anthropology and aerospace engineering, respectively, made a home in which curiosity, discussion, and science were common. I can remember vividly my mother actively supporting civil rights for minorities in the early 1960’s, and my father explaining the ingenuity behind jet engines, supersonic flight, and the Space Shuttle. When my parents bought me a used, 4 1/4-inch Newtonian telescope, I would climb out my window onto the patio roof every night to examine the planets, nebulae, and the galaxies. Saturn’s rings still seem spectacular to me.
I enjoyed the public schools in Los Angeles from 1959 to 1972. I struggled to do well in classes, but was mesmerized by chemistry and physics in high school. The structure of atoms and the grandeur of galaxies seemed intimately linked. At UCLA, I played cello in the orchestra and sports in the intramural leagues. But I spent most of my time in the physics library. Among my many inspiring professors were Ray Orbach, George Abell, and Mike Jura. When I floundered at a simulation of heating and cooling balance in interstellar gas, professor Jura admonished me, “If nature can do it, so can you.” That can-do attitude proved invaluable later in detecting planets.
In graduate school at UC Santa Cruz, Dr George Herbig took me to the Lick Observatory “120-inch” telescope every month, where he taught me the value of painstaking care in observational astrophysics. He taught me stellar spectroscopy, and gave me a project to measure Doppler shifts of “T Tauri” stars. Challenged by invisible systematic errors, I wondered if Doppler shifts could be measured to arbitrarily high precision. Meanwhile, a young professor, Steven Vogt, built new, high resolution spectrometers and detectors that ultimately would make planet detection possible.
After finishing my PhD dissertation on the Zeeman effect in Sun-like stars, I received a Carnegie Fellowship at the “Mt Wilson and Las Campanas Observatories” in Pasadena. During my first year there, I suffered from feelings of inadequacy and incompetence. My Zeeman work had been criticized and indeed I saw little future in it. One morning in the shower, I decided to hunt for planets around other stars.
I took a faculty position at San Francisco State University and met a brilliant student there, Paul Butler, who was pursuing both a bachelor’s degree in chemistry and a Master’s degree in physics. We decided to search for planets, inspired by the Canadian astronomer, Bruce Campbell, who cleverly employed Hydrogen Flouride gas as a wavelength standard. In 1986, Paul hunted for a chemical alternative to hazardous HF gas, finally settling on molecular iodine at 50 C as optimal. We had no access to telescopes, but Lick Observatory generously gave us a few nights on the 24-inch “CAT” telescope and one or two nights during full moon on the “120- inch” telescope each semester. From 1987-1995, we took repeated spectra of 120 nearby stars, but our Doppler shift precision was no better than 15 meters per sec. When we told other astronomers about our search for extrasolar planets, they would usually smile politely, look down at their shoes, and change the subject.
However, Paul and I spent thousands of hours inventing and testing a wide variety of computer algorithms to improve the Doppler precision. A breakthrough came in the early 1990’s when we realized that the spectrometer’s instrumental profile was smearing the spectrum asymmetrically, causing false Doppler shifts. When Paul went to the University of Maryland to obtain a PhD, he continued the development of the Doppler code while we also continued to acquire spectra at Lick. Paul was the engine that powered our planet search to success.
In 1995, our algorithms were finally achieving a precision of 5 meters/sec, just as the Swiss team led by Michel Mayor announced the first extrasolar planet. We confirmed it within a week, and then used our new technique to process the spectra from the 120 stars we had been observing. We announced our first two planets two months later, orbiting 70 Virginis and 47 Ursae Majoris. Within a couple of years we found 10 more, and to date (August, 2005) our team has found 107 exoplanets (the smallest being 7 Earth-masses) without a single false claim.
In 1999 we discovered the first multiple-planet system (upsilon Andromedae) which had the clear architecture of a planetary system, and we also co-discovered a transiting planet that dimmed the star, proving the planet’s existence (for those who doubted). Most naysayers about the existence of our planets were satisfied.
The discovery of extrasolar planets has sparked a new search for habitable worlds. Indeed, my research group, led by Paul and Drs Debra Fischer and Steven Vogt, is building a new 2.4-meter telescope designed to find the rocky, terrestrial planets. Meanwhile, I get the greatest pleasure from bringing the news of other worlds to students, who will lead the next-generation quest for life in the universe.
2 September 2005, Hong Kong