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Giant mirrors to bring in winter sunlight

The industrial town of Rjukan with 3,500 inhabitants is nestled deep in a valley floor in southern Norway. With the sun moving low across the sky during winter, it gets no direct sunlight between September and March.

Floro MerceneNorwegian industrialist Sam Eyde started the community here in Rjukan when he founded ‘Norsk Hydro’ taking advantage of an enormous waterfall to produce chemical fertilizers. In 1900, just 300 inhabitants were spread out across in scattered farms. Eyde was concerned his workers weren’t getting enough sunshine during the winter months. An idea was suggested at that time by a worker to install mirrors on a peak but Eyde felt they lacked the technology to make it work so he built a cable car instead to the top of the mountainside to allow people to recharge their vitamin D levels with sunlight on a mountain top.

The village of Viganella, sits at the bottom of a steep valley, too, in the Italian Alps, which suffered from the same problem set up the mirror successfully in 2006.

After 5 years of debate, the Rjukan town council finally agreed to build the mirrors. Known as heliostats, they have been designed to trace the movements of the sun and reflect the light directly onto Rjukan’s main square. Helicopters have hoisted three huge mirrors into position some 450 meters above the town at the top of the valley. They are controlled by a computer to follow the path of then sun, adjusting to the best angle to ensure the town square is bathed in light. Solar panels will power equipment to automatically wash the mirror and move them into position.

Last month, town folks started to enjoy winter sunlight for the first time in history at their town square.