NASA's Galaxy Evolution Explorer grabbed this ultraviolet image of the wispy gas clouds of the Cygnus Loop, a remnant of a supernova that occurred 5,000 to 8,000 years ago. The remnant is about 1,500 light years away from Earth. It is in the direction of the constellation Cygnus and, if visible to the naked eye, it would take up as much space in the sky as three full moons.
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Rebecca J. Rosen is a senior editor at The Atlantic, where she oversees coverage of American constitutional law and government in the Battle for the Constitution series.