ANIMATE4.COM / SCIENCE PHOTO LIBRARY ANIMATE4.COM / SCIENCE PHOTO LIBRARY
Animation showing Kepler's second law of planetary motion. Kepler's three laws were published in 1609 (first and second laws) and 1619 (third law). Kepler's second law states that a line linking the planet to the Sun sweeps out an equal area in any given time. At its furthest from the Sun, an area a1 is swept out in time t1. Closest to the Sun, an area a2 is swept out in time t2. If t1 and t2 are the same time, the areas a1 and a2 are identical. This is because a planet travels more quickly closer to the Sun.
Model release not required. Property release not required.