Kepler's equation
（重定向自Kepler equation）
In orbital mechanics, Kepler's equation relates various geometric properties of the orbit of a body subject to a central force.
It was first derived by Johannes Kepler in 1609 in Chapter 60 of his Astronomia nova, and in book V of his Epitome of Copernican Astronomy (1621) Kepler proposed an iterative solution to the equation. The equation has played an important role in the history of both physics and mathematics, particularly classical celestial mechanics.