Why is the earths orbit elliptical?
Answer Hello Sanford, There is no force that acts on the earth perpendicular to the force of the sun. (At least nothing significant enough to explain this. Ignore the other planets and the moon.) Wherever it is in its orbit, the gravity vector is straight towards the sun. Consider point A, the point of the orbit that is farthest from the sun. When the earth gets to that point it is going rather slow. It’s going slowly because it has just completed a section of the orbit that increased the distance from the sun. It sacrificed kinetic energy for a gain in the potential energy of its extreme altitude from the sun. So it’s going too slow to follow a circular orbit. Remember, centripetal acceleration, in a condition of circular rotation, needs to be v^2/r to keep the object in the circular path. Repeating another way: the magic magnitude of centripetal (meaning toward the center) acceleration, required for circular rotation, is v^2/r. At the radius r of point A, v is too slow, the gravity i
