As portions of the US are battered by snowstorms and shrouded beneath gray skies, a European startup is developing a light fixture that mimics the sun.

Each CoeLux fixture models the sunlight of a specific locale, be it the cool color and strong shadows of equatorial countries, the even glow of Mediterranean sunlight, or the slightly dimmer and warmer, but more striking patterns found along the Arctic Circle.

CoeLux fixtures use traditional LEDs, calibrated to the same wavelengths as the sun. However, accurately recreating sunlight also requires mimicking subtle variations caused by the atmosphere, which varies in thickness and composition depending upon where you are on earth. CoeLux uses a milimeters-thick layer of plastic, peppered with nanoparticles, that does essentially the same thing in your living room. CoeLux's inventor, Professor Paolo Di Trapani hasn't made any disclosures about how the nanotechnology works in practice, but an impressive list of peer-reviewed publications, industry awards, and testimonials from customers provide comfort that these devices actually work as advertised.

Despite the dynamic nature of the light, the fixtures feature no moving parts. Different qualities of light are created by manipulating the size and placement of the LED "hot spot"—the portion of the fixture meant to represent the sun—within the fixture's two-foot wide and 5-foot long frame. The tropical unit has the largest hot spot, the Nordic unit the smallest. The thickness of the plastic sheet varies as well, thicker for the Nordic light than the equatorial light, to mirror the atmosphere. The light doesn't emit any ultraviolet rays, so it won't give you a tan or ease your seasonal affective disorder, but it will make the darkest basement, warehouse, or subterranean dwelling feel like a solarium.

Shining a New Light on an Old Problem

For thousands of years, man has tried to bring sunlight into dark spaces. Egyptians used complex arrays of mirrors to bring natural light deep within the pyramids, but this is labor intensive and difficult to achieve without a huge slave-labor force.

Northern European palaces from the 18th century feature bright Trompe l'oeil frescos of sunny skies, designed to bring cheer during long winters. Las Vegas casinos use similar techniques, augmented with LEDs and other technologies, to make you think you're outdoors, not frittering away your money in the soulless confines of a casino.

Engineers have previously tried to replicate the sun's spectrum in light bulbs. Though technically accurate, these bulbs miss the mark by 238,900 miles or so. "Even a perfect reproduction of the sun's spectrum fails in reproducing the natural light simply because it reproduces the natural light on the moon, and not on the Earth," says CoeLux co-founder Paolo Di Trapani. Without the subtle interplay of atmospheric particles, even a careful recreation of the solar spectrum will seem alien.

Di Trapani is a a professor with impressive list of technical publications on his CV, but when asked about CoeLux, his first references are to works of art, like The courtyard of Saint Ambrogio church in Milan or Van Gogh's painting The Sower. "CoeLux is not copying nature, but putting nature on a stage, like art does," says Di Trapani. "It focuses attention on the most relevant feature of natural light—the dynamic interplay between the sky and sun light."

Like an artist, Di Trapani judges the quality of his light by the quality of the shadows it produces. "Objects are illuminated by the direct and warm light of the sun, which casts their sharp shadows," he says. "However, these shadows are not just dark, or grey, but bluish as in nature from being under the diffused light of the sky."

You can get a CoeLux now, but expect to spend five figures. Di Trapani is eager to see what happens when architect start imagining new kinds of buildings enabled by this technology. Just as elevators enabled the construction of skyscrapers, and air conditioning allowed buildings to become wider, Di Trapani believe CoeLux could allow for the creation of "groundscrapers," or buildings that stretch hundreds of feet into the ground, yet don't make you feel you've descended into a deep, dark cave.