megastructure

Dyson spheres aren't solid shells — they're swarms of solar collectors around a star. Here's how they'd work, why we'd build one, and how we'd spot aliens using one.

A Dyson sphere — a structure capturing all of the Sun's energy — would harness 3.86 × 10²⁶ watts, more than a trillion times humanity's current power use. Building it requires more material than exists in any individual planet, but could in principle be done by dismantling Mercury or several asteroids.