IT sounds like something only a Bond villain would propose, but the Nazis planned a mile-wide "space gun" powered by the sun.

The giant mirror could be used to focus the sun on a target - like the magnifying glasses used by children to create fire.

A long-forgotten article from Life magazine in 1945 revealed how "US Army technical experts came up with the astonishing fact that German scientists had seriously planned to build a “sun gun".

The giant orbital mirror 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 came to renowned rocket scientist Hermann Oberth in 1923.

With an estimated cost of three million marks and taking 15 years to construct, the original purpose of the space mirror was to provide the people of Earth with sunshine on demand, anywhere on the globe. But Oberth later described it as the "ultimate weapon".

"My space mirror" he wrote, "is like the hand mirrors that schoolboys use to flash circles of sunlight on the ceiling of their classroom. A sudden beam flashed on the teacher’s face may bring unpleasant reactions."

In 1945, when the victorious Allies began sifting through captured war plans, it emerged that the Nazis had updated Oberth’s proposals and begun looking into the possibility of the Third Reich building a mirror weapon in orbit 22,236 miles above the Earth.

Details of the sun gun emerged again after they were discussed by US military experts and appeared on internet forums.

Life magazine believed it would be put into orbit in pre-assembled sections. It would also contain a manned space station, with 10m holes in which supply rockets could dock, hydroponic gardens to provide oxygen and solar-powered generators for electric power.

Once in orbit, the "master rocket" for the project would unreel six cables. Spinning the rocket on its axis would extend the cables radially, allowing construction to begin.

The Germans are not the only nation to look into harnessing the power of the sun. In 1999, the Russians unveiled a plan to use a mirror to reflect sunlight to Earth during winter.

And in the James Bond film, The Man with the Golden Gun, Christopher Lee's villain, Scaramanga, unveils a powerful solar-powered laser gun which can destroy almost anything.

