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(MUSIC)

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JOAN CARTAN-HANSEN, HOST: IS

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THE MOON SHRINKING?

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SCIENTISTS THOUGHT SO, BUT NEW

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RESEARCH SAYS THE MOON IS ALSO

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EXPANDING A LITTLE BIT.

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AND THAT'S CAUSING MOONQUAKES.

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WHEN THE APOLLO ASTRONAUTS

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LANDED ON THE MOON, THEY LEFT

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BEHIND SOME SEISMOMETERS TO

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KEEP TRACK OF LUNAR

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MOONQUAKES.

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SCIENTISTS THOUGHT SOME

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MOONQUAKES WERE CAUSED BY

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IMPACTS FROM METEORITES

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AND OTHERS WERE CAUSED BY THE

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MOON'S SURFACE BEING WARMED

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AND COOLED BY THE SUN EVERY

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TWO WEEKS.

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BUT THERE WERE MOONQUAKES THAT

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THEY JUST COULDN'T EXPLAIN.

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NOW THEY THINK THESE

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MYSTERIOUS MOONQUAKES ARE

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CAUSED BY A COMBINATION OF

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ESCAPING INTERNAL HEAT AND THE

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EARTH'S GRAVITATIONAL PULL.

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THE MOON HAS A CORE, MANTLE

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AND CRUST LIKE THE EARTH.

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BUT PLANETARY GEOLOGISTS

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THOUGHT THE MOON'S CORE HAD

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ALREADY COOLED DOWN,

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APPARENTLY NOT.

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ITS STILL RUNNING HOT ENOUGH

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TO SHAKE THINGS UP.

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FOR MORE INFORMATION ABOUT THE

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MOON, CHECK OUT THE SCIENCE

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TREK WEBSITE.

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YOU'LL FIND IT AT

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IDAHOPTV.ORG/SCIENCE TREK