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eruvian astronomers Jorge Melendez of the Australian National University and Ivan Ramirez of the University of Texas at Austin have discovered the best "solar twin" to date, using the 2.7-meter Harlan J. Smith Telescope at the McDonald Observatory. Their findings suggest that the Sun's chemical composition is not unique, as some previously thought. <br /><br />The star, HIP 56948, is more like the Sun than any yet seen, and is 200 light-years away in the constellation Draco, the dragon. The star may be a billion years older than the Sun. <br /><br />Only three solar twins were previously known: 18 Scorpii, HD 98618, and HIP 100963. But while they were all like the Sun in many ways, there was one major difference: the amount of lithium they contained. They all had several times more than the Sun. Astronomers wondered if the Sun was unique in its low amount of lithium. <br /> <br /> <br />This image is a finder chart for HIP 56948. The star is located 200 light-years away in Draco, the dragon. It's too dim to see with the unaided eye. Tim Jones/McDonald Obs./UT-Austin [larger image] <br />The discovery of this new solar twin puts that question to rest: it has the same low lithium content as the Sun. The study turned up another solar twin, HIP 73815, that contains a similarly low amount of lithium.<br /><br />The question of chemical peculiarities in the Sun is related to the "anthropic principle" — is there something special about the Sun that has allowed life to spring up in our solar system? Their findings don't answer that completely, but they do show that when it comes to the Sun's chemical composition, the answer is an emphatic "no." <br /><br />Melendez and Ramirez's findings suggest the opposite, so-called "Copernican" view: It is possible that life is common elsewhere in the universe. They suggest that stars like HIP 56948 would be good targets for SETI (Search for Extra-Terrestrial Intelligence) researchers. <br /><br />The star has already been studied by the McDonald