Why do planets revolve around the sun in an elliptical orbit?
Because of the way the sun warps space. Have you ever seen those funnel things at museums, where you drop a ball or a penny in and it spins around and around, eventually falling into the hole at the center? That’s the physical idea behind all gravitation: the warping of space due to the presence of mass (it’s an imperfect analogy for a couple reasons, but the principle is the same). The orbits are elliptical because of this strange geometry of the even stranger thing called spacetime. The equations we use to describe this warping of space (as laid out by Einstein) are not the CAUSE of the orbits. The universe is what it is. We have some idea of how and why things are the way they are, but the equations merely describe the truth, they are not the truth itself.
