why is the orbit of earth not exactly a circle even though sun attracts it with the same force of gravity???

Answer 1

gravitational forces come from other suns and planets that interact with our solar system

Answer 2

When you solve the equations that describe the Newtonian motion of a body around a larger body, you find the solution for the orbit is a conic section, i.e. an ellipse or hyperbola. There is an arbitrary constant which defines the eccentricity or how different it is from a circle; the circular orbit is just one special case which is unlikely to occur. This arbitrary constant can only be defined for a given system and relates more to the initial conditions when the solar system was formed than subsequent interations with other bodies. Naturally these other interactions will change the orbit but they are perturbations on the original ellipse.

Seasons were mentioned in an answer. These are due to the rotational axis of the earth not being perpendicular to the plane of orbital rotation and nothing to do with the orbit curve itself.

Answer 3

Orbits are in general initially elliptical and the circular orbit is a 'special case' of an ellipse. When an orbit forms initially, there is no reason for it to be circular. The initial velocity and distance can be any values that produce a stable orbit. Orbits gradually approach circularity through collisions with other orbiting bodies. Collisions occur when the bodies' orbits intersect; the more circular the orbits are, the fewer collisions occur. So there's a natural tendency for orbits to evolve toward circularity, but at some point the incidence of collisions falls off and true circularity will be very rare. And as other answers have mentioned, gravitational perturbations from other orbiting bodies will also prevent perfect circularity.
EDIT: I have to take issue with Pearlsaw's answer. From conservation of momentum, two bodies will revolve about their common CG in whatever orbit has been established, circular or elliptical. The only effect of the mass ratio is on the relative sizes, not the shapes, of the orbits. A simple application of force to either body would change its orbit to or from circular regardless of mass ratio. Near-earth satellites are commonly launched into elliptical orbits which, if left alone, would persist. But typically their orbits are "circularized" by another rocket burn.

Answer 4

Helen, kirchwey and Pearlsaw have answered this pretty completely, but it might interest you to know that when you work in a rotating reference frame (in other words make the line joining the earth and sun one of the axes) the elliptical orbits appear as harmonic oscillations about the mean orbital distance.

Put differently, the system looks just like a mass at the end of a spring. In stable orbits, the period of the mass-spring system is exactly the period of one orbit (Newtonian case).

Like all oscillators, there is an exchange between kinetic and potential energy - the total energy remains constant. This helps to understand why the planets move faster when they are closer to the sun in their orbits - which is one of Kepler's Laws.

hth

Answer 5

The force of attraction is the same as GMm/ r^2.

But the acceleration of earth toward the Sun is GM/r^2
and the acceleration of Sun toward the earth is Gm/r^2
The former is greater than the latter.
These are in the opposite directions.
The relative acceleration of the planet is G [M+m] /r^2 and is toward the Sun.

Using this we can show that the square of the period of revolution is proportional to the cube of the semi major axis of an elliptical orbit, which is Kepler's third law.

Only if we ignore the acceleration Gm/r^2 as small, we will get a circular orbit and the speed of earth will be a constant along its circular path.
If we take into account this force, then the path becomes elliptical and the speed of earth is not a constant but the radius vector traces equal areas in equal intervals of time.
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Only in the special case where the masses of the two bodies are equal, then the accelerations towards each other will be equal and opposite and the path will be a circle of radius equal to half the distance between them.
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If the masses were different , then the center of masses will be nearer to the greater mass and hence the path will be an ellipse.
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Answer 6

great question! I had to do a splash analysis right here. My suspicion replaced into that an ellptical orbit is greater sturdy than a around orbit, and something like that seems to be the case. investigate the hyperlink under for a greater ideal rationalization than i ought to grant, yet as I are conscious of it, we are in a position to (case in point) launch a satellite tv for pc into Earth orbit that has a splendidly around orbit. it is hard to do, although. There are 2 forces performing upon the satellite tv for pc: gravity, and its very own inertia. Its inertia clearly proceeds alongside a as we talk line, yet gravity pulls it in direction of Earth; the consequent of those 2 forces pulls it decrease back in direction of Earth, so which you have an orbit. a splendidly around orbit means that the floor velocity of the satellite tv for pc (velocity of satellite tv for pc with comprehend to the closest element to it on earth's floor) is persevering with. yet the two forces on the satellite tv for pc, inertia and gravity, would desire to completely cancel as a effect! As I pronounced, it is hard to do. It is clever then that the Earth has an elliptical orbit, via fact the equipment isn't suited. If it have been completely around, wow. that must be very mind-blowing. Does this help?

Answer 7

The effect is caused by the the moon.

The moon is to large to be considered as a true moon rather the Earth/moon combination behave as a pair of planets revolving around a common point, the barycentre. This point is on a straight line joining the centre of the pair. The exact point can be calculated as is depends only on the masses of the two bodies. It's actually inside the earth.

Hence the effect is not large. The earth is actually closest to the sun in December and furthers in June, so it does not affect the seasons, which are caused by the tilt of the earth's axis

Ian M

Answer 8

Because nothing obits in a perfect circle.
If you spin a top it moves around a little.
The earths orbit is affected by the gravity of the other planets a little.
Also collisions with large asteroids may have changed the earths path a little.

Answer 9

because the sun is not the only gravitation pulling on the earth. we have the moon of course but also he other planets. the gravity of the moon raises the "high tide" the sun is aprox 93 million miles away. I think the planets are closer just a couple like mars, venus. they pull on the earth too.

Answer 10

In as much that all the planets behave similarly, I believe its because of the earths interaction with other heavenly bodies outside the solar system.