Gravity governs the structure of the universe. Test your knowledge of this fundamental force with our gravity quiz!
Author's Note: What would happen if I drilled a tunnel through the center of the Earth and jumped into it?
Politicians like to spout off about how we shouldn't spend money on space when so many problems here on the home planet need solving. I strongly disagree, but perhaps deep exploration of Earth could offer a compromise. To explore the ocean floor, lower crust or mantle requires technology on par with spaceflight -- in some ways, it's harder -- and could produce comparable economic, educational and technological side benefits.
In many ways, we know more about the moon than we do about our own oceans, or about the Earth's interior. It's high time we changed that.
- Angier, Natalie. "The Enigma 1,800 Miles Below Us." The New York Times. May 28, 2012. (Oct. 5, 2012) http://www.nytimes.com/2012/05/29/science/earths-core-the-enigma-1800-miles-below-us.html?pagewanted=all&_r=0
- Darling, David. "The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity." Wiley. Nov. 8, 2002.
- Fisher, Richard. "The Quest to Drill the World's Deepest Hole." New Scientist. July 5, 2012. (Oct. 5, 2012) http://www.newscientist.com/gallery/deepest-drilling
- Free Map Tools. "Tunnel to the Other Side of the Earth." (Oct. 4, 2012)http://www.freemaptools.com/tunnel-to-other-side-of-the-earth.htm
- Levitt, Tom. "The $1 Billion Mission to Reach the Earth's Mantle." CNN. Oct. 2, 2012. (Oct. 4, 2012) http://www.cnn.com/2012/10/01/tech/mantle-earth-drill-mission/index.html?hpt=hp_t3
- Locke, Susannah F. "FYI: If I Fell Through the Earth, What Would Happen in the Center?" Popular Science. Feb. 22, 2011. (Oct. 5, 2012) http://www.popsci.com/science/article/2011-02/fyi-if-i-fell-through-earth-what-would-happen-center
- NASA. "Earth Fact Sheet." Nov. 17, 2010. (Oct. 4, 2012) http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
- NOVA ScienceNOW. "Journey Through the Center of the Earth." June 10, 2008. (Oct. 3, 2012) http://www.youtube.com/watch?v=wuHau1LTH8Y
- Plait, Phil. "Ten Things You Don't Know About the Earth." Discover Magazine. Sep. 8, 2008. (Oct. 4, 2012) http://blogs.discovermagazine.com/badastronomy/2008/09/08/ten-things-you-dont-know-about-the-earth/
- Reich, Henry. "What if the Earth were Hollow?" Minute Physics/Vsauce. Aug. 26, 2012. (Oct. 5, 2012) http://youtu.be/jN-FfJKgis8
- Robbins. "The Channel Tunnel." (Oct. 4, 2012) http://www.robbinstbm.com/case-study/the-channel-tunnel/
- Robertson, Eugene C. "The Interior of the Earth." U.S. Geological Survey. Jan. 14, 2011. (Oct. 5, 2012) http://pubs.usgs.gov/gip/interior/
- Shegelski, Mark. "Would You Fall All the Way Through a Theoretical Hole in the Earth?" Scientific American. April 21, 2003. (Oct. 5, 2012) http://www.scientificamerican.com/article.cfm?id=would-you-fall-all-the-wa
- Singh, Sunil Kumar. "Gravity." Sep. 26, 2007. (Oct. 3, 2012) http://cnx.org/content/m15087/latest/
- UCSB Science Line. "If I Were to Dig a Hole to the Very Core of the Earth, then Jump, Would I Float Because the Gravity is All Converging on One Spot?" (Oct. 5, 2012) http://scienceline.ucsb.edu/getkey.php?key=3224