----------------------------------- habarnam 24 Apr 2006 21:09 SETI ----------------------------------- in caz ca nu stiati .. The Planetary Society's Optical SETI Telescope High on a wooded ridge in Harvard, Massachusetts an odd-looking structure has sprung up recently. Appearing from a distance like a small work shed, a closer inspection reveals some unusual features, including a retractable roof and a large side window with a sliding screen. A look inside is even more puzzling, for there, bolted to the ground, one finds a large elongated object, made of metal bars and mirrors. This strange object, that looks like nothing at all, represents one of the most ambitious SETI projects ever undertaken: an optical telescope dedicated exclusively to the search for extraterrestrial life. On April 11, 2006, the telescope pointed its giant mirror at the sky for the first time, and began a systematic search for light signals from an alien civilization. http://www.planetary.org/programs/projects/seti_optical_searches/ Si in caz ca va intrebati ce au .. The new Optical SETI telescope is a 1.8 meter (72 inch) reflector. Reflector telescopes use a mirror to capture the light, whereas refractors use a lens. Built around a circular mirror with a diameter of 1.8 meters, the new telescope is the largest optical telescope east of the Mississippi! The telescope's mirror has a spherical, rather than parabolic curvature. The mirrors of most telescopes have parabolic curvature, because spherical curvature makes the images near the edge of the field of view a bit fuzzy. Since the optical SETI telescope will not be used to take beautiful pictures but to detect brief flashes of light, this does not matter. Horowitz and his team therefore opted for the simpler (and cheaper!) spherical design. The mirror's curvature is f/2.5. This means that the ratio of the mirror's focal length (4.4 meters) to its diameter (1.8 meters) is 2.5. http://www.planetary.org/programs/projects/seti_optical_searches/facts.html :( .. eu am plans putin ...