As the 1990s began, the only planetary star system known was our own Solar System . The first extra-solar star system was discovered orbiting a pulsar in 1991. Slight changes in the precise arrival times of the pulses from the central small dense neutron star gave evidence of orbiting planets . Pictured above is an artist's sketch of a planet discovered orbiting HD217107 . As the decade comes to a close, over two dozen planetary star systems have been identified, one recently confirmed by the detection of a slight eclipse by the planet itself.
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