Supernova 1987A, the nearest observed supernova since Kepler's Supernova of 1604, was originally tracked by NASA in 1987. In 2004, however, the Hubble Space Telescope's Space Telescope Imaging Spectrograph broke down and scientists lost their view of this supernova remnant. That's since been repaired. This week scientists reported in a study why that ring you see in the accompanying image appears so bright.
Polar mesospheric clouds illuminated by an orbital sunrise as photographed by the Expedition 24 crew of the International Space Station.
The ignition of Development Motor-2, the largest and most powerful solid rocket motor designed for space flight.
Scientists celebrated ten years of discoveries by Cluster, a space mission that is bringing back data on the magnetosphere, the northern lights and the solar wind. The accompanying image shows Cluster spacecraft flying in formation.
Water on Mars?
NASA rovers exploring Mars came across evidence suggesting that water might have existed on the Red Planet - though it would have been too acidic to support life. But scientists examining new evidence from a stone outcropping - called the Comanche Outcrop - now say that not all the water on Mars was necessarily highly acidic. And so the big tease about whether life ever existed on Mars continues.
Why was a dying star surrounded by a gigantic cloud of hot water vapor. Observing this dying star, referred to as IRC+10216,from ESA's Herschel infrared space observatory, scientists discovered that ultraviolet starlight is the key ingredient for making water in space.
Taken by the Hubble Space Telescope Spiral, the galaxy NGC 4921 is estimated to be 320 million light years away from Earth.
As Hurricane season kicks into high gear, a view of the Atlantic Ocean on Aug. 31. Hurricane Earl (lower left) passing Puerto Rico, Tropical Storm Fiona located to Earl's east, and Tropical Storm Danielle far in the Northern Atlantic.
Hurricane Earl, as seen from a high-definition camera aboard NASA's Global Hawk uninhabited aerial vehicle on Sept. 2.
NASA's Terra satellite captured this image of hurricanes Danielle (top) and Earl (bottom) in the Atlantic Ocean.
Artist's illustration of NASA's Phoenix Mars Lander starting to shut down operations as winter sets in. The far-northern latitudes on Mars experience no sunlight during winter and this will mark the end of the mission because the solar panels can no longer charge the batteries on the lander.
Sometime before 2018, the agency intends to send a spacecraft into the solar atmosphere. (Read more here. The accompanying image is a representation of Solar Probe Plus that will get launched.
With its nuclear fuel now exhausted, time is running out on the central star of this the Hourglass Nebula.