The space shuttle Challenger explodes shortly after lifting off from the Kennedy Space Center in Cape Canaveral, Fla., on Jan. 28, 1986. Bruce Weaver/AP hide caption

itoggle caption Bruce Weaver/AP

To eat, chitons use their teeth, which look like black bulbs with bluish highlights, to grind up rock. Lyle Gordon/Northwestern University hide caption

itoggle caption Lyle Gordon/Northwestern University

The planet Kepler-10b, seen in this artist's drawing, is about 1.4 times the size of Earth and is the smallest planet ever discovered outside of our solar system. NASA hide caption

itoggle caption NASA

A human baby typically weighs about 6 percent of what its mother weighs. This baby, seen on a beach in Costa Rica, crawls next to an olive ridley sea turtle. Yuri Cortez/AFP/Getty Images hide caption

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The Nintendo 3DS offers 3-D imagery without 3-D glasses. But scientists warn that if young children use the device in 3-D mode, it could be harmful to their vision. Shuji Kajiyama/AP hide caption

itoggle caption Shuji Kajiyama/AP

This tooth, which was also found in Denisova Cave, has a DNA structure similar to that of a finger bone. Its shape and physical structure are, however, very different from that of Neanderthals and modern humans, leading researchers to believe that the Denisovans are a distinct group. David Reich, et al./Nature hide caption

itoggle caption David Reich, et al./Nature

Semiconductor computer chips like this one rely on electricity -- positive or negative charges -- to store data. Using high power magnets in a lab, researchers have developed a new way to store data in the spin of an atom's nucleus. HYNIX/AFP/Getty Images hide caption

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Eat Up: Eating a large meal at the holidays won't have a big impact on your weight, says one physiologist. That's because your brain keeps a close watch on food intake and can tolerate the occasional big meal. It's slow, steady weight gain that's more problematic. iStockphoto.com hide caption

itoggle caption iStockphoto.com