An artist's illustration of events on the sun changing the conditions in near-Earth space. NASA hide caption

itoggle caption NASA

Gary Hug built what he calls the Sandlot Observatory, with its 22-inch reflector telescope, behind his house near Topeka, Kan. Courtesy of Gary Hug hide caption

itoggle caption Courtesy of Gary Hug

This artist's illustration shows what NuSTAR should look like in orbit after its 30-foot-long mast deployed. JPL-Caltech/NASA hide caption

itoggle caption JPL-Caltech/NASA

Astronauts Shannon Walker and David Saint-Jacques test a probe in the waters off Key Largo, Fla. Their research may help NASA set foot on an asteroid someday. Miami Herald/MCT via Getty Images hide caption

itoggle caption Miami Herald/MCT via Getty Images