Astronomers Spot First Possible Exoplanet Outside Our Galaxy

A possible Saturn-sized planet identified in the distant Whirlpool Galaxy could be the first exoplanet to be detected outside the Milky Way. From a report: The exoplanet candidate appears to be orbiting an X-ray binary -- made up of a normal star and a collapsed star or black hole -- with its distance from this binary roughly equivalent to the distance of Uranus from the sun. The discovery opens up a new window to search for exoplanets -- planets orbiting stars beyond our Sun -- at greater distances than ever before. Although nearly 5,000 exoplanets have been detected so far, all of them are in the Milky Way galaxy -- with few further than about 3,000 light years from Earth. An exoplanet in the spiral Messier 51 (M51) galaxy -- also called the Whirlpool Galaxy because of its distinctive shape -- would be about 28m light years away. Dr Rosanne Di Stefano of the Center for Astrophysics at Harvard and Smithsonian in Cambridge, US, who led the research, said: "Since the 1750s, it has been conjectured that the dim distant nebulas, now called galaxies, are island universes: large, gravitationally-bound stellar populations similar to our home, the Milky Way. Our discovery of the planet candidate ... gives us the first peek into external populations of planetary systems, extending the reach of planet searches to distances roughly 10,000 times more distant."

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