Why are orbits elliptical?
A derivation of the ellipse is found at the link below, if you have a math background and like that type of explanation. A hand waving explanation goes like this – in your hand is a rock. You can throw the rock upwards, straight out, or down. If you have really strong arms, you could throw that rock straight out with just enough speed to have it fall down at the same rate as the ground underneath it curved away, and in this case you have a circular orbit. If you throw the rock in any direction but straight out, and/or throw it with a speed that is not the ‘magical speed’, then you will get an elliptical orbit (in this case you probably need to be way above the earth so the rock does not hit the ground). Why an ellipse? Because of the math. You may feel uncomfortable with why the sun is at one focus, and not the other, or somewhere else. Again, it comes out of the math. It may help to realize that the satellite orbits very quickly on the side of the ellipse near the sun, and very slowly
