Fast-spinning young Earth pulled the moon into a yo-yo orbit | Science News

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Fast-spinning young Earth pulled the moon into a yo-yo orbit

Just 24,000 years after its birth, the moon zipped through its lunar cycle in little more than 35 hours

11:05am, March 18, 2015
moon phases composite

ODDBALL ORBIT  The young moon’s short, oblong orbit produced a lunar cycle unlike the one seen nowadays (as seen in this composite of some phases of the moon in 2013), new research illustrates.

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The Earth and moon’s celestial dance was a lot wilder during the pair’s youth.

By simulating the early moon’s orbit, researchers have reconstructed what the moon’s phases would have looked like during the solar system’s early years. The result, presented online March 10 at, reveals a moon that alternated rapidly between its sunlit and shadowy sides and bounced like a ball toward and away from Earth.

Scientists believe that the moon assembled from debris left over from a collision between Earth and a Mars-sized object roughly 4.5 billion years ago. In a 2012 paper in Science, researchers proposed that the Earth spun rapidly during this period. They calculated that gravitational tug from this fast rotation pulled the young moon into an orbit 12 times as oblong as the current

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