How to Build a Dyson Sphere, the Ultimate Megastructure

The sun has all the energy we could ever conceivably need, but we haven't been all that efficient in harvesting that energy ...yet. One way to capture the sun's energy is to build a Dyson sphere, or a megastructure surrounding the sun. Kurzgesagt explains how that could happen, which involves an army of robots launching umbrellas with a rail gun from Mercury. (via Geeks Are Sexy)