Elliptical orbits, equal areas, and T²∝a³ — visualized
Inner Solar System
Kepler's Third Law: T²∝a³
Kepler 1: Planets move in ellipses with the Sun at one focus.
Kepler 2: Equal areas swept in equal times — highlighted in yellow.
Kepler 3: T² ∝ a³ — period squared proportional to semi-major axis cubed.
Planets shown: Mercury, Venus, Earth, Mars.