Whatever name it sailed under — International Sun-Earth Explorer 3, and International Cometary Explorer, among others — this spacecraft has scored a number of firsts over the years, including the first comet flyby. NASA Goddard Spaceflight Center hide caption

itoggle caption NASA Goddard Spaceflight Center

An image shot by NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite on Wednesday. It shows multiple wildfires in Calif. trailing smoke into the Pacific Ocean. Lynn Jenner/NASA/Goddard hide caption

itoggle caption Lynn Jenner/NASA/Goddard

An artist's rendering of Kepler-186f, the first validated Earth-size planet to orbit in the habitable zone of a distant star. T. Pyle/NASA/SETI Institute/JPL-Caltech hide caption

itoggle caption T. Pyle/NASA/SETI Institute/JPL-Caltech

Japan Aerospace Exploration Agency astronaut Aki Hoshide makes a space walk outside the International Space Station in 2012. NASA/Getty Images hide caption

itoggle caption NASA/Getty Images

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

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