For helping to find asteroids, NASA has set up a contest with cash awards. In 2012, the agency said that "more potentially hazardous asteroids, or PHAs, are closely aligned with the plane of our solar system than previous models suggested." NASA hide caption

itoggle caption NASA

Russian personnel are the first to meet space station crew members when they return to earth. Bill Ingalls/NASA hide caption

itoggle caption Bill Ingalls/NASA

People view the Northern Lights over Bamburgh Castle Beach Thursday in Northumberland, England. A powerful solar flare caused the aurora borealis to be visible farther south than usual. Josh Maidwell/Barcroft Media/Landov hide caption

itoggle caption Josh Maidwell/Barcroft Media/Landov

Images of Folsom Lake, a reservoir in Northern California, show the severity of the state's drought. The photo at left, taken on July 20, 2011, show the lake at 97 percent of total capacity and 130 percent of its historical average for that date. The photo at right shows the lake on Jan. 16, 2014, when it was at 17 percent of capacity and 35 percent of its historical average. California Department of Water Resources hide caption

itoggle caption California Department of Water Resources

The iconic "Earthrise" photo taken by astronaut Bill Anders through a window on the Apollo 8 command module on Dec. 24, 1968. Bill Anders/NASA hide caption

itoggle caption Bill Anders/NASA