This image shows the grid structure of the major pathways of the brain. It was created using a scanner that's part of the Human Connectome Project, a five-year effort which is studying and mapping the human brain. MGH-UCLA Human Connectome Project hide caption

itoggle caption MGH-UCLA Human Connectome Project

Researchers have analyzed the fossil imprints of of raindrops, like the ones shown here, to study the atmosphere of the Earth, as it was 2.7 billion years ago. The rule at the top is 5 centimeters, or about 2 inches, long. W. Alterman/University of Pretoria hide caption

itoggle caption W. Alterman/University of Pretoria

President Obama signs the Affordable Care Act in the East Room of the White House on March 23, 2010. Data suggest that racial attitudes of ordinary Americans shape both how they feel about the health care overhaul and how intense those feelings are. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images