Weatherwatch: solar technology holds a mirror to the ancient world

The principle of the heat ray Archimedes reputedly used to defend Syracuse is now being employed to generate powerAt the end of the film Indiana Jones and the Dial of Destiny, Harrison Ford goes back in time to the Hellenic city of Syracuse in Sicily and witnesses the Roman siege of the city in 213-212BC. There he meets local resident Archimedes who had invented weapons to defend his city, including a heat ray made by holding up shiny brass mirrors to focus the sun's rays and set fire to the Roman ships.Whether the weapon was actually built, or if it worked is not clear (several modern day attempts of building such weaponry have yielded mixed results), but the principle behind it is now used to generate solar power. Parabolic or flat mirrors that track the sun, focus the sun's rays into an intense beam of light that heats a solar furnace which gets so hot it can melt salt. The heat stored in the molten salts is used to generate electricity, even at night, answering the criticism that solar power doesn't work in the dark. And by siting solar plants in areas with abundant sunshine, such as the Sahara, it helps solve the problem of cloudy weather, or shortage of sunlight in winter. Continue reading...