What is the reason why the Earth moves as per an elliptical Orbit?

Question

Is there any correlation with the earth's mass?

Perhaps the reason is given by Relativity Theory?

Also the gravitational interaction of other planets with the earth is minimal compared to that of the Sun.So there must be another reason?

How is the precession of the perehelium have to do with it?

Answer 1

Force of attraction exists between earth and sun. Based on the theories expressed by Kepler and subsequently studied and explained by Newton, an external force which existed during the formation of earth. This force on earth imparted earth a velocity that was greater then critical velocity to revolve in a circular path around sun but less than the escape velocity. Any body imparted with such velocity will rotate in an elliptical orbit. Thus the earth also rotates in an elliptical orbit around sun.

Answer 2

The earth and the sun are attracted to each other, the earth has momentum in an opposing direction. The elliptical orbit is a sum of these forces, as well as the less influential attractive gravitational forces from all other massive bodies outside the earth. We are left to presume the earth has momentum from some initial accelerating force, and this might be augmented by rotational forces.

Answer 3

Gravity is the reason. Kepler discovered the elliptical orbit, and Newton explained it with his law of universal gravitation.

Without looking up or deriving the rules of orbital mechanics, the general idea is that the radial attraction between two bodies -- the sun and the earth -- varies inversely as the square of the distance between them, so there's a stronger attraction when the earth is closer to the sun -- as it is during part of the year.

To counteract that stronger attraction, the earth travels faster when it's closer to the sun ... the increased speed is associated with increased centripetal acceleration, hence outwardly directed radial force, necessary to offset the stronger gravitational attraction.

Those two paragraphs above relate to changing, albeit balanced, inward and outward radial forces -- stronger when the earth is closer to the sun, and weaker when it's farther away.

I also mentioned that the earth's speed is faster when it's close in. When you add that to the mix, you get the relation that the earth's orbit sweeps out equal areas in equal times.

All that is from Kepler, as explained by Newton's gravitation. When you satisfy all these conditions (forces of attraction and repulsion, orbital speeds), the resulting orbit is elliptical, with the sun at one focus.

Kepler observed all this, but could not explain it. Newton derived Kepler's laws from the principal of universal gravitation. Newton could not, however, explain gravitation itself.

There is a derivation of all this, and I've gone through it more than once, but I'm not going to look it up now.

You asked whether mass and/or relativity has anything to do with this. As to mass, yes. The radius of the elliptical orbit is directly proportional to the orbital velocity and inversely proportional to the product of the sun's and earth's masses ... and since the sun's mass is orders of magnitude greater than the earth's, it's the earth that orbits around the sun rather than vice versa.

Relativity has virtually nothing to do with it. Newtonian mechanics handles it quite well. (But relativity is needed to explain precession of Mercury's orbit.)

[Edit: Goring wants to know what precession has to do with it. Without looking it up, I don't recall the details. But I know that Newton's laws could not adequately explain how Mercury's orbit precesses ... it explained some, but not all, of the observed precession. Furthermore, this apparent shortcoming was well known to scientists. Then someone applied the General Relativity equations to Mercury's orbit, and the result of the calculation matched Mercury's precession precisely. That's about as much of the story as I recall. End edit]

You could say General Relativity (the curvature of space) could be used instead of gravitation to explain the elliptical orbit, but you'd arrive at the same result as Newton, with much greater effort.

So the short answer to your question is "gravity."

Answer 4

Probably the best reason is that there is no such thing as a perfectly circular orbit. The gravitational forces of the other planets would see to that, as small as they are.

Answer 5

because of mass and the gravitational pull exerted by other planets and most importantly by the sun. also distance between objects count alot

Answer 6

Because lots of orbital velocities produce ellipses, but only a few produce circles.

Answer 7

centrifugal and centripetal forces

it's drawn inwards by the sun's gravity but it's speed wants to throw it outwards on a tangent. the Harmony of ying yang works on cosmic levels too

Answer 8

The orbit is just barely elliptical...

Answer 9

You got me there, but I guess it is easier than moving in a rectangular one.