When a projectile without air resistance travels a range that is significant compared to the Earth's radius (above ≈100 km), the curvature of the Earth and the non-uniform Earth's gravity have to be considered. This is, for example the case with spacecraft or intercontinental projectiles. The trajectory then generalizes from a parabola to a Kepler- ellipse with one focus at the center of the Earth. The projectile motion then follows Kepler's laws of planetary motion.