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A total solar eclipse confirmed part of Einstein's Theory of Relativity

July 18, 2017

It’s a revered scientific fact now, but part of Albert Einstein’s Theory of Relativity might have remained just that if not for a total eclipse in 1919.

It was then that British astrophysicist Sir Arthur Eddington verified Einstein’s theory asserting that light from a star near a massive object would be different than light away from a very massive object. Eddington’s pictures of stars taken at the time demonstrated the change in position of the stars due to the gravitational pull of the sun, said George Mason University’s Harold A. Geller.

“That’s the uniqueness of an eclipse,” said Geller, an associate professor within Mason’s Department of Physics and Astronomy and the director of the Mason Observatory. “Einstein had to wait until that time before one of his predictions from general relativity would be confirmed. A total eclipse is the only time you can actually see starlight when the sun is in our sky.”

Eclipses occur when the sun, moon and Earth are aligned such that the moon's shadow passes across the Earth.

A large swath of the continental United States will be privy to a rare total eclipse on Aug. 21, where the moon passes between the sun and the Earth and blocks all or part of the sun for nearly three hours. Its path will stretch across portions of 14 states from Lincoln Beach, Oregon, to Charleston, S.C., according to NASA. Observers outside that path will see a partial eclipse, where the moon covers part of the sun’s disk. It will mark the first total eclipse for the contiguous United States since 1979.

“Everyone in the United States will be able to see something,” Geller said. “It’s a celestial event.”

Art Poland, a research professor within Mason’s Department of Physics and Astronomy, has witnessed previous total eclipses while in Montana and in Turkey. He characterized the experiences as “one of the most exciting and dramatic events” of his entire life.

“If you are in the region of totality, it becomes so dark that you can literally see the stars in the middle of the day,” said the retired NASA astrophysicist.

Harold A. Geller can be reached at hgeller@gmu.edu or 703-993-1276.

Art Poland can be reached at apoland@gmu.edu or 703-993-8404.

For more information, contact John Hollis at 703-993-8781 or jhollis2@gmu.edu.

About George Mason

George Mason University is Virginia’s largest public research university. Located near Washington, D.C., Mason enrolls 35,000 students from 130 countries and all 50 states. Mason has grown rapidly over the past half-century and is recognized for its innovation and entrepreneurship, remarkable diversity and commitment to accessibility.