Dr. Geoff Marcy Lecture Highlights
October 13, 1999 - Los Altos, California

Picture of Dr. Geoff MarcyKicking off a series of lectures titled The Silicon Valley Lectures, Dr. Geoff Marcy,  the world's foremost planet discoverer delivered a wonderfully engaging lecture to a packed auditorium at Foothill College in Los Altos California. Dr. Marcy of U.C. Berkeley and SFSU shared in layman's terms what has been learned about planets orbiting other stars followed by a question and answer session.  

Dr. Marcy started his lecture with a slide of the planet earth surrounded by the dark of space, saying exness that this was "the most remarkable object" in our solar system.  Saying the "chances for biology within our solar system are great", he touched on Mars, Jupiter's moon Europa and Saturn's moon Titan. Marcy explained how our own sun wobbles under the gravitational influence of Jupiter as this planet orbits on a 12 year cycle. It is this wobble that he and other scientists have used to detect 21 planets around other stars (14 by Marcy and his team).

47 UMa velocity curve with the orbital fit for a period P=1094 days. Error bars are shown. The RMS of the residuals to the orbital fit are 9 m/s. The derived minimum companion mass is: M sin i = 2.41 M jup.Leaving our own solar system he moved to the search for planets around nearby stars.  Dr. Marcy and his team used observational data from Lick Observatory and more recently the Keck Observatory to study the wobble of other stars using very precise measurements of the Doppler shift in the spectrum of the stars measured over months and years. Dr. Marcy discussed the observational data regarding the planets found around the stars 47 Ursae Majoris, 16 Cyg B, 51 Peg and the planetary system Upsilon Andromedae. In his lecture, Dr. Marcy used four beautiful depictions of the planets, as imagined by the artist Lynette Cooke. 

47 Ursae Majoris b and Moon as imagined by space artist Lynette Cook The planet orbiting 47 Ursae Majoris is a 2-3 Jupiter mass planet with an orbital period of about 3 years. Although all water in the large gas giant would be in solid form, Marcy suggested that such a planet is likely to have one or more moons could harbor liquid water and perhaps even life. Another planet orbiting 16 Cygni B is in a highly elliptical orbit, which brings a planet extremely close to it's sun and then carries it a great distance away. Such an orbit would not be conducive exness trading to life on the moons of such a world due to any water being boiled away as the planet approached the star closely. Moving to the next extrasolar planet, 51 Peg is closely orbited by a planet smaller than Jupiter with an orbital period of only 4.2 days. This planet is tidally locked with the same side facing the star in perpetuity. 
1998-1999 Lynette R. Cook, All Rights Reserved, Used by special permission

A Triple-Planet System Orbiting Ups AndromedaeOf most interest is Upsilon Andromedae which is the first planetary system discovered outside of our solar system. Dr. Marcy described the use of Fourier transformations to analyze the patterns of oscillations in the data to determine the periods of the planets orbiting the star. Despite an apparently random pattern of wobble in this star, three planets account for the data observed.  The planets are orbiting in elliptical rather than circular orbits - as have been most of the observations to date. This is perhaps the "first evidence that our solar system is a quirk" due to its circular orbits pondered Marcy. 

In his conclusion, Dr. Marcy stated that while we have been lucky to start exness trade to understand the nature of planets, which number in the "tens or hundreds of billions", there still remain significant puzzles.  We need a better thesis on the formation of planetary systems to answer the question "is our solar system some sort of bizarre freak", given that most of the discoveries to date exhibit elliptical orbits that are not conducive to life. He pointed to two future NASA missions that will help answer these questions, the Space Interferometry Mission scheduled for launch in June 2005 and father out the "grandest telescope conceived of", the Terrestrial Planet Finder (TPF) which will be able to image and measure the spectrum of extrasolar earth sized planets. TPF is planned for launch about 2011 and will face daunting challenges in terms of both funding and technology. 
Image: NASA Origins Program

Following the lecture, Marcy fielded a large number of questions, the most memorable being from that of a 10 year old asking about the formation of the asteroid belt. The final question that Marcy answered was as to any upcoming announcements of new discoveries. Dr. Marcy confided that there were a "half a dozen stars" exhibiting strong indications of planets that would be made public within the next several months!

A very enjoyable lecture! I am definitely looking forward to Dr. Jill Tarter lecture on November 17, which is the second in the series of lectures at Foothill College in Los Altos.

-- Stan Schonberg for SETIweb.org