Nazi Germany's "sun gun"

Back in 1945, Life magazine revealed to its readers how “U.S. Army technical experts came up with the astonishing fact that German scientists had seriously planned to build a ‘sun gun’.”This, the magazine explained, would have been a gigantic orbital mirror that would “focus the sun’s rays to a scorching point on the earth’s surface.” The German army, readers were told, “hoped to use such a mirror to burn an enemy city or to boil part of an ocean.”The idea had been originally proposed by the seminal rocket scientist, Hermann Oberth, in 1923. As late as 1957, he was still convinced that his space mirror would become a reality....