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Over the last three centuries, there have been many advances in optical telescopes. To find planets that may support life like our own planet, astronomers have to search for planets that orbit stars at the "Goldilocks" distance: not so close that they will be unbearably hot "Jupiters," and not so far away that they will be frozen "Plutos." Locating objects within the bright glare of a host star is no easy task. However, as reported in a recent paper in Nature by a Jet Propulsion Laboratory (JPL) group, scientists have made tremendous progress in the field. The JPL group used "wavefront correction" techniques applied to coronagraphs to optically observe a planet orbiting its host 33 light years away, with a relatively small (1.5 m) Earth-based telescope. When it comes to searching for extraterrestrial intelligence (SETI), the tool of choice for the last fifty years has been a radio telescope, rather than an optical telescope. Almost 1,000 star systems have been scrutinized for "intelligent" radio signals using increasingly sophisticated phased-array antennas. The Allen Telescope Array (funded largely by Paul Allen, cofounder of Microsoft) in California currently has 42 dish antennas, each 6 m in diameter. It is eventually supposed to grow to 350 dishes, and should be able to observe one million star systems within a decade.
Date of Publication: June 2010