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For First Time, Einstein's Theory of Relativity Used to Weigh a Star

Binary stars are the only stars scientists can directly gauge, because their orbits around each other reveal their masses. Now, astronomers from the Space Telescope Science Institute in Baltimore have succeeded in measuring the mass of an isolated star using a technique first suggested by Albert Einstein's general theory of relativity in 1936. The method exploits the fact that a large mass, like a star, can bend the path of light. Although the effect is tiny, measuring the deflection can reveal the mass of the light-bending star. Einstein's theory was proven in 1919 when scientists measured the curving of starlight around the sun during a total solar eclipse.