Reported May 2007

BACKGROUND: Astronomers at the University of California, Santa Cruz are seeking the public’s help to find and understand planets outside our solar system. No advanced degree or fancy equipment is needed: just a computer, Internet access, and an interest in astronomy. The project is called Systemic, and it enlists volunteers to identify and explore other planetary systems in the Milky Way. This will help create a virtual database of extrasolar planetary systems. Several hundred people have already volunteered in the project’s introductory phase.

HOW IT WORKS: Systemic is modeled on other successful public participation projects, such as SETI@home, where users download a screensaver that uses their personal computer’s processing power to analyze radio telescope data. But instead of just a screensaver, the astronomers wanted something that would more fully engage the user. The project involves a sophisticated simulation of the search for planets by creating a data set of 100,000 stars. Participants can analyze this virtual galaxy themselves with freely available software. They can analyze the data for a target star. They can change planetary properties like mass, shape of the planet's orbit, and the time it takes for the planet to orbit its sun to find a configuration that best fits the data. Complicated large-scale simulation systems with multiple planets require a human eye and patience to arrive at an accurate description, which is a data-intensive, time-consuming process. By comparing the simulated observations with the real observations, the researchers hope to better understand how well, or how poorly, the search process collects a census of extrasolar planets.

WHY IT’S NEEDED: Albert Einstein’s theory of general relativity says that gravity occurs because the mass of a celestial object, like the sun, warps the surrounding space-time. Planets orbiting the star follow that curvature. Astronomers find planets outside our own Solar system by measuring slight wobbles in a star’s motion caused by the gravitational tug of an orbiting planet. Nearly 200 planets have been found orbiting other stars in our galaxy. However, this technique tends to locate planets that are both very large – on a par with Jupiter – and also close to their star. To make the process even slower, astronomers must share time on the few very large telescopes and are limited to observations lasting only a few days. This also limits what parts of the sky astronomers can observe, and thus the current data on planets outside our solar system is incomplete. Systemic’s simulated search uses the same kind of planetary wobble data that astronomers measure, as well as incorporating the observational biases that occur as they collect real data.

The American Astronomical Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Marcus Woo, Public Information
University of California at Santa Cruz
831-459-2495
mwoo@ucsc.edu

American Astronomical Society
Washington, DC 20009-1231
202-328-2010
http://www.aas.org
aas@aas.org

ON THE WEB...

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