Yup, up is down, black is white, the Earth is no longer round ...
OK, let's be real. The Earth didn't one day suddenly slim down, develop a bulge or turn into a triangle. It's never been round, and it was Sir Isaac Newton (who just had to put his nose in everything) who said it was actually an oblate spheroid. So just tell the kids that.
Perhaps you're not familiar with the term? Imagine a lovely, round ball of clay. It's sitting on the table peacefully. Unable to stand its perfect plumpness, you place your hand on the top of the ball and press gently. The ball begins bulging in the middle, while the rounded top and bottom flatten out a bit. The result? An oblate spheroid.
That's what we mean when we say the Earth is round. It's actually a bit bulky in the middle, much like the stomach of a middle-aged man. And the shape isn't entirely constant; earthquakes and plate tectonics change the figure of the Earth. You might not know that Earth tides -- the gravitational pull of the sun and moon on land -- affect our planet just like ocean tides. As the Earth spins, it will redistribute mass back to the equator in a process termed true polar wander [source: Choi].
Now that you're prepared to be Super Science Parent and blow your kids' minds with Earth facts, check the next page for more great links that will astound.
- Allen, Jesse. "Ask an Astrophysicist." NASA's Imagine the Universe. Dec. 1, 2005. (March 29, 2012) http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980202b.html
- Buis, Alan. "Chilean Quake May Have Shortened Earth Days." NASA. March 1, 2010. (March 29, 2012) http://www.nasa.gov/topics/earth/features/earth-20100301.html
- Buis, Alan. "Japan Quake May Have Shortened Earth Days, Moved Axis." NASA. March 14, 2011. (March 29, 2012) http://www.nasa.gov/topics/earth/features/earth-20100301.html
- Choi, Charles Q. "Strange but True: Earth is not Round." Scientific American. April 12, 2007. (March 29, 2012) http://www.scientificamerican.com/article.cfm?id=earth-is-not-round
- Krauss, Lawrence Maxwell. "Atom: an odyssey from the big bang to life on earth-- and beyond." Back Bay Books. 2002.
- McDonald, Charlotte. "Who, What, Why: Is the Earth getting lighter?" BBC News Magazine. Jan. 30, 2012. (March 29, 2012) http://www.bbc.co.uk/news/magazine-16787636
- NASA StarChild. "Stars." (March 29, 2012) http://starchild.gsfc.nasa.gov/docs/StarChild/universe_level2/stars.html
- St. Maurice, Dr. Martin. "Is it true that we're breathing the same molecules once breathed by the dinosaurs, Julius Caesar or Jesus Christ?" Marquette Magazine. 2011. (March 29, 2012) http://www.marquette.edu/magazine/recent.php?subaction=showfull&id=1273588200
- U.S. Geological Survey Hawaiian Volcano Observatory. "Earth Tides and Video Monitoring." May 28, 1998. (March 29, 2012) http://hvo.wr.usgs.gov/volcanowatch/archive/1998/98_05_28.html
With a sequel out now, what did Al Gore's documentary 'An Inconvenient Truth' get right? Learn more in this HowStuffWorks Now article.