Question

I know that Earth's orbit is elliptical and that the Sun is at one of its focal points. What is at the other focus? It seems that there should be something that has a graviational effect on the Earth equal to that of the Sun to keep Earth from a circular orbit.

Answer 1

Nothing is there... nothing is is required. The gravitational attraction of the sun is sufficient to keep the earth in orbit

Answer 2

stan is right that there is nothing there but there is a point in space that is the other foci, but that point doesn't do anything to the Earth

Answer 3

believe it or not the sun is. the eccentricty of the earths orbit is very close to zero and the sun is very large so both foci are in the sun. they start with little kids telling them the path is ellipical but to keep from confusing them they do not draw both points in the sun very close. remember an ellipse is a for a lack of a better term a squashed circle with two centers. nothing keeps the two foci from being very close. since both points are so close and in the sun the problem can be reduced to a simple circular acceleration problem which allows for the easy approximations of newton's universal law of gravitation.

Answer 4

Ah, yes.... but it is not required to be so

Answer 5

The gravitational attraction between two bodies, one of them in a fixed point, yields several diferent possible mathematical solutions. The most simple is a circular orbit, and an eliptical orbit is also possible. Keppler laws describe these orbits.

Answer 6

Thanks for the answers.