The sun can be a powerful source of renewable energy, but so can the night sky. Now, a team of scientists have created a device that turns the cold of space into enough electricity to power an LED light. As described in a paper published on Thursday in the journal Joule, the device is based off of a thermoelectric generator that creates electricity from the difference in temperature between a ‘hot side’ and a ‘cold side.’ The researchers—UCLA scientist Aaswath Raman, and Stanford scientists Wei Li and Shanhui Fan—decided to take this idea one step further and use the ambient environment of Earth as a heat source and the cold of outer space as one gigantic cold sink. The prototype consists of four stilts supporting two plates sandwiched between a thermoelectric generator. One plate is aimed at the ground, the other at the sky. The downward-facing plate draws heat from the air around it, while the upward-facing plate is paired with an aluminum disk painted black. The disk acts as an emitter that radiates heat into space through Earth’s atmosphere, cooling the plate to below ambient temperature.