Comet ISON on Nov. 14. Courtesy of Mike Hankey hide caption

itoggle caption Courtesy of Mike Hankey

KABOOM! A NASA illustration of a gamma-ray burst. They occur, the space agency says, when "a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star." NASA.gov hide caption

itoggle caption NASA.gov

The average temperature in winter is about -72 degrees Faharenheit. The IceCube Lab is illuminated in the moonlight. Emanuel Jacobi/NSF hide caption

itoggle caption Emanuel Jacobi/NSF

NASA's PhoneSat, a 4-by-4-inch CubeSat satellite, will use an Android smartphone as its motherboard. It was among the 29 satellites launched Tuesday from Wallops Island, Va. Another miniature satellite, developed by high school students, also was on board. Dominic Hart/AP hide caption

itoggle caption Dominic Hart/AP

NASA's MAVEN, short for Mars Atmosphere and Volatile Evolution, with a capital "N" in EvolutioN, atop a United Launch Alliance Atlas V rocket, lifts off from Cape Canaveral Air Force Station, on Monday. John Raoux/AP hide caption

itoggle caption John Raoux/AP

An artist's rendition of the GOCE satellite shows the craft in its orbit around Earth. After four years of studying oceans and gravity fields, GOCE re-entered the atmosphere over the Southern Atlantic Ocean Sunday night. ESA /AOES Medialab hide caption

itoggle caption ESA /AOES Medialab

An artist's rendering of the European Space Agency's GOCE satellite, which is now out of fuel and expected to fall to Earth sometime Sunday or early Monday. European Space Agency/AOES Medialab hide caption

itoggle caption European Space Agency/AOES Medialab

These NASA/ESA Hubble Space Telescope images reveal a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt designated P/2013 P5. NASA, ESA, D. Jewitt (University of California, Los Angeles), J. Agarwal (Max Planck Institute for Solar System Research), H. Weaver (Johns Hopkins University Applied Physics Laboratory), M. Mutchler (STScI), and S. Larson (University of Arizona) hide caption

itoggle caption NASA, ESA, D. Jewitt (University of California, Los Angeles), J. Agarwal (Max Planck Institute for Solar System Research), H. Weaver (Johns Hopkins University Applied Physics Laboratory), M. Mutchler (STScI), and S. Larson (University of Arizona)