The answer was an ellipse. For 2,000 years ... That belief was a mirage. Ironically, Kepler’s misfortunes illuminated the world. In life, everyone encounters hardships, large and small.

Keep your eye on the ball” is a motto for many athletes—and for astronomers trying to find Earth-threatening space rocks ...

If this were true, then each planet's orbit should take the form of Kepler's ellipse, a shape like a football, though somewhat more rounded. Halley recalled that Hooke immediately "affirmed that ...