A California-based start-up, Reflect Orbital, plans to launch a constellation of 4,000 satellites with giant reflective mirrors in low-Earth orbit to illuminate the night side of the planet by bouncing sunlight back down from space. Each satellite would carry a square, high-reflectivity mylar mirror ranging in width from 33 feet to an astonishing 180 feet. From orbit, these mirrors would illuminate about 4.8 square kilometres at a time, creating moving patches of brightness as the satellites race overhead. The company claims this light would be far more powerful than a full moon, effectively delivering daylight to places meant to be dark.
The idea has already moved beyond sketches and simulations. Last year, Reflect Orbital tested a large mirror attached to a hot-air balloon and has since applied to the US Federal Communications Commission for a licence. Its first prototype satellite, Earendil-1, carrying a 60-foot mirror, could launch as early as April 2026. A dozen more satellites are planned over the following two years, with the company ultimately aiming to deploy all 4,000 by 2030.
At first, the idea seems useful. Reflecting sunlight from space could keep solar panels running at night, help rescuers find people in remote areas, or give people more time to work. But the downsides could be serious. Night is not wasted time; it is a vital part of nature’s workings. Lighting up the dark on a global scale could disrupt plant growth, accelerate glacier melting, and harm shallow marine life, in addition to impacting human circadian rhythms and the behaviour of nocturnal creatures.
In the last century, space was largely the realm of a few powerful states—first a theatre for military rivalry, then a stage for headline-grabbing science like Moon landings, planetary probes, and orbital telescopes. But today, cheaper launches and smarter spacecraft have invited a rush of private ventures, unlocking fresh possibilities but also creating regulatory gaps. Nations remain legally responsible for what their companies do in orbit. Ambitious research can lead to real breakthroughs, but it needs to be grounded in careful thinking. That’s why many scientists are wary of Reflect Orbital’s plan to shine redirected sunlight at night, citing massive engineering challenges, risks to astronomy, ecological concerns, and doubts about whether the idea could work as advertised.