Looking for a Wink From ET

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Science  29 Jan 1999:
Vol. 283, Issue 5402, pp. 629d
DOI: 10.1126/science.283.5402.629d

After years of cocking their ears for radio signals from extraterrestrial civilizations, astronomers are now turning their eyes skyward. Private funding for three new, low-cost “optical SETI” (Search for Extraterrestrial Intelligence) initiatives was announced last week by The Planetary Society, a space advocacy group in Pasadena, California.

Although most ongoing SETI searches use large radio telescopes, some SETI scientists have been arguing that flashes of laser light—both optical and infrared—would be a better way for extraterrestrials to communicate. Whereas radio waves travel farther, “lasers are clearly superior for direct, point-to-point interstellar communications out to ranges of several thousand light-years,” says Stuart Kingsley, director of the small Columbus Optical SETI Observatory in Ohio, which began its work in 1992.

Now, three new efforts are mirroring Kingsley's on a much larger scale. One, begun last fall at Harvard University's Oak Ridge Observatory in Massachusetts, is watching stars for patterns in the form of repeated bright pulses lasting as briefly as a few billionths of a second. The second, at the Leuschner Observatory of the University of California, Berkeley, will begin regular observations next month with an automated telescope. In the third effort, also Berkeley-based, planet hunters will search for steady, bright signals of a single color—another possible means of intelligent broadcast—in thousands of stellar spectra they have collected.

If scientists do find a signal, says Berkeley astronomer Dan Wertheimer, it will likely be one intentionally directed toward Earth—“They would know about us.” Any dialogue would be rather sluggish because of the great distances, but not out of the question—astronomers estimate there are hundreds of sunlike stars within 50 light-years.

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