In 2013, NASA's Cassini spacecraft captured this image of Earth from Saturn. Seen here, our planet is 898 million miles away (1.44 billion kilometers) and appears as a blue dot at center right. NASA/JPL-Caltech/Space Science Institute hide caption

itoggle caption NASA/JPL-Caltech/Space Science Institute
itoggle caption Clay Bennett

politicalcartoons.com David Fitzsimmons hide caption

itoggle caption David Fitzsimmons

Benny and the Elevators perform during the game between the NBA's Chicago Bulls and Houston Rockets Dec. 25, 2012. The Bulls are one of 10 NBA teams playing on Christmas Day this year. David Banks/Getty Images hide caption

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Step back in time: This is what 100 million years ago looked like, in a galaxy far, far away. ESO hide caption

itoggle caption ESO

Decades ago, the SAT test was seen as a measure of raw ability, not as something students ought to cram for. Now, test prep is a huge industry. Linguist Geoff Nunberg wonders what exactly students learn when they're flipping through vocabulary flashcards. Mario Tama/Getty Images hide caption

itoggle caption Mario Tama/Getty Images

politicalcartoons.com J.D. Crowe hide caption

itoggle caption J.D. Crowe