	Copernicus H, a typical "dark-halo" crater, was a target of observation by Lunar Orbiter 5 in 1967. Dark-halo craters were once believed to be volcanic in origin rather than the result of impacts. The Orbiter image showed that the crater had blocks of ejecta like other craters of similar size, indicating an impact origin. The halo results from excavation of darker material (mare basalt) at depth.