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BOB HIRSHON (host):
Why does the earth have a tilt? I’m Bob Hirshon and this is Science Update.
We owe our seasons to the earth’s nearly 23 and a half degree tilt. A Science Update listener called our toll free line—1-800-WHY-ISIT to ask what caused the tilt. NASA physicist Betsy Pugel says it all happened billions of years ago, when the Earth was just a baby planet.
BETSY PUGEL (NASA):
Long ago when our solar system was forming, you had lots of different things that were coalescing into spheres; those spheres ended up having orbits and sometimes run into each other. So it may be that once upon a time, earth didn’t have a tilt in its axis, but some major collision or collisions happened that—boop—that kind of tipped earth off of its axis.
HIRSHON:
She says some scientists think that without the resulting seasonal changes, life may not have formed on the planet at all. I’m Bob Hirshon, for AAAS, the science society.
