Researchers who studied ancient Chinese chronicles of solar eclipses found that a day is now seven hundredths of a second longer than it was nearly 4,000 years ago because the Earth is spinning more slowly. The length of a day “just keeps getting longer and longer,” said Kevin Pang, who conducted the study as an astronomer at the National Aeronautics and Space Administration’s Jet Propulsion Laboratory.
Just as a spinning ice skater slows down by extending her arms, Earth’s rotation on its axis slows as tidal interactions make the moon orbit Earth more quickly and become more distant from it, he said Wednesday. “Four billion years ago, the moon was only one-third as far away as it is now, and the day was only eight hours long at the time,” said Pang, whose study will be published soon in the British journal Vistas in Astronomy. A day was seven hundredths of a second shorter in 1876 B.C.
(Note: this article was probably from prior to 1995.)
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