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

NASA took a series of images to create this "timelapse" view of comet ISON's trip around the sun. NASA hide caption

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The Long March-3B carrier rocket carrying China's Chang'e-3 lunar probe blasts off from the launch pad at Xichang Satellite Launch Center in southwest China's Sichuan Province on Monday. Li Gang /Xinhua /Landov hide caption

itoggle caption Li Gang /Xinhua /Landov

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

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

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

Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, left, Soyuz Commander Mikhail Tyurin of the Russian space agency Roscosmos, and Flight Engineer Rick Mastracchio of NASA, hold the Olympic torch that will be flown with them to the International Space Station, during a press conference on Wednesday. Bill Ingalls/NASA hide caption

itoggle caption Bill Ingalls/NASA

Nie Haisheng, Zhang Xiaoguang and Wang Yaping aboard the Tiangong-1 space module in June. China is leading what some see as a space race among Asian countries: It has worked on a lunar rover, a space station and an unmanned mission to Mars. Wang Yongzhuo/Xinhua /Landov hide caption

itoggle caption Wang Yongzhuo/Xinhua /Landov