Scientists Use Relativity to Measure a Star’s Mass
Astronomers scanning the skies with NASA’s Hubble Space Telescope have pulled off a feat that even Albert Einstein had declared all but impossible: they’ve witnessed the subtle bending of one star’s light by another star’s gravity and used that distortion to measure a star’s mass.
The findings, unveiled Wednesday at a meeting of the American Astronomical Society and published in the journal Science, confirm a key tenet of Einstein’s landmark general theory of relativity and introduce a new tool with which to explore a fundamental property of stars.
The general theory of relativity, presented in 1915, describes how gravity can distort the path of light, altering its trajectory. In 1919, the theory was proved correct when, during a solar eclipse, an expedition led by Sir Arthur Eddington discovered that stars near the edge of the blocked sun’s disc were not where they were supposed to be. Their apparent position had moved because the sun’s gravity had distorted the path of their starlight, just as Einstein had predicted.