A woman in Senegal charges her cellphone using a port in her solar-powered LED lantern. Bruno Déméocq/Courtesy of Lighting Africa hide caption

itoggle caption Bruno Déméocq/Courtesy of Lighting Africa

Physics is full of big, interesting questions about phenomenon such as black holes. This illustration shows the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus. M. Kornmesser/ESO hide caption

itoggle caption M. Kornmesser/ESO

A mentor can help bridge the gulf between having an interest in a subject and actually pursuing that interest through action. Above, a boy gazes up at an image of Albert Einstein on a wall in Tunis, Tunisia. Fethi Belaid/AFP/Getty Images hide caption

itoggle caption Fethi Belaid/AFP/Getty Images

Master science communicator Brian Greene shares the spotlight with Muppet scientist Dr. Bunsen Honeydew ahead of the 2008 World Science Festival in New York City. Scott Gries/Getty Images hide caption

itoggle caption Scott Gries/Getty Images

The spiral galaxy known as NGC 3521 lies in the constellation of Leo, a mere 35 million light-years away. Now go flush and see if you understand the connection between the two. O. Maliy/ESO hide caption

itoggle caption O. Maliy/ESO

This artist's impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus. M. Kornmesser/ESO hide caption

itoggle caption M. Kornmesser/ESO