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Solar eclipse image taken aboard Gemini 12.
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Courtesy of NASA

Can an Eclipse Change Gravity?
News story originally written on July 6, 1999

A question more than four decades old will be answered soon. The last solar eclipse of the millennium was used by scientists around the world to test a theory first developed in 1954. A French economist named Maurice Allais believes that during an eclipse, Earth's gravitational pull slighty increases.

Allais tested his theory during two total solar eclipses, one in 1954, and another in 1959. He used an instrument called a Foucault pendulum. This special tool swings in the same direction of the Earth's axis. This means that as the Earth turns below it, the pendulum's path doesn't change.

During the tests, Allais found that the rate of movement changed by an extra 0.15 degrees. This would correlate with a slight increase in the Earth's gravitational pull. If his theory holds true, our entire concept of gravity will change. Through the past 40+ years, no one has been able to duplicate Allais' experiment with any success.

David Doever of NASA's Marshall Space Flight Centre in Huntsville decided to put the experiment to the test. Using the latest technology, Doever and his colleague, Ron Koczor, should put an end to this baffling question. Doever doesn't expect to find proof to support Allais, but believes such an theory must be investigated.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA