A study finds that more than 800 species of vertebrates are moving closer to extinction, a fate that befell the golden toad. U.S. Fish and Wildlife Service via Wikimedia Commons hide caption

itoggle caption U.S. Fish and Wildlife Service via Wikimedia Commons

A snowflake from Kiruna Sweden. Large, well-formed crystals like this one, which is between 2 and 5 mm, usually form when the temperature is around -15 degrees Celsius. A special photo-microscope and colored lights were used to capture the image. Kenneth Libbrecht/Lenart Nilsson Award hide caption

itoggle caption Kenneth Libbrecht/Lenart Nilsson Award

In The Mind's Eye, Oliver Sacks looks at how blind people use other senses to "see" the world, and how people with aphasia and visionary disturbances learn to compensate with their other senses. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Researchers say one reason physicists are good at poker is because their brains are particularly attuned to thinking about probability, statistics and modeling. Mikko J. Pitkanen/iStockphoto.com hide caption

itoggle caption Mikko J. Pitkanen/iStockphoto.com

Proof that the earth is round: a sailor atop the mast of a ship catches sight of land before a sailor on deck. Sacrobosco's The Sphere hide caption

itoggle caption Sacrobosco's The Sphere