(MUSIC)

JOAN CARTAN-HANSEN, HOST: IS

THE MOON SHRINKING?

SCIENTISTS THOUGHT SO, BUT NEW

RESEARCH SAYS THE MOON IS ALSO

EXPANDING A LITTLE BIT.

AND THAT'S CAUSING MOONQUAKES.

WHEN THE APOLLO ASTRONAUTS

LANDED ON THE MOON, THEY LEFT

BEHIND SOME SEISMOMETERS TO

KEEP TRACK OF LUNAR

MOONQUAKES.

SCIENTISTS THOUGHT SOME

MOONQUAKES WERE CAUSED BY

IMPACTS FROM METEORITES

AND OTHERS WERE CAUSED BY THE

MOON'S SURFACE BEING WARMED

AND COOLED BY THE SUN EVERY

TWO WEEKS.

BUT THERE WERE MOONQUAKES THAT

THEY JUST COULDN'T EXPLAIN.

NOW THEY THINK THESE

MYSTERIOUS MOONQUAKES ARE

CAUSED BY A COMBINATION OF

ESCAPING INTERNAL HEAT AND THE

EARTH'S GRAVITATIONAL PULL.

THE MOON HAS A CORE, MANTLE

AND CRUST LIKE THE EARTH.

BUT PLANETARY GEOLOGISTS

THOUGHT THE MOON'S CORE HAD

ALREADY COOLED DOWN,

APPARENTLY NOT.

ITS STILL RUNNING HOT ENOUGH

TO SHAKE THINGS UP.

FOR MORE INFORMATION ABOUT THE

MOON, CHECK OUT THE SCIENCE

TREK WEBSITE.

YOU'LL FIND IT AT

IDAHOPTV.ORG/SCIENCE TREK