Scientists often refer to the mesosphere as the “ ignorosphere ”—a region that’s too high for planes or weather balloons to explore, yet too low for satellites to probe. Despite our technological advances, we’ve yet to find a decent way to monitor this large stretch of air, which lies about 37 miles (60 kilometers) above the surface. But engineers are inching towards a solution—one inspired by a toy-like invention from the 19th century.

A Nature paper published today presents a proof-of-concept for an extremely lightweight, disc-like structure that levitates thanks to sunlight, no fuel required. Crafted from ceramic aluminum with a chromium base, the device floats on photophoresis, which literally means “light-driven motion.” When sunlight strikes the device, the differences in heat

See Full Page