Why planets are moving in elliptical path rather than in circular path?

Answer 1

From observations, Kepler formulated three laws of planetary orbits which describe how the planets move on their orbits around the Sun. By studying the observations, Kepler derived these laws, but he didn't understand why planets are forced to move in this way. The concept of gravity wasn't fully understood until Isaac Newton, who could then show that Kepler's laws are simply a consequence of the gravitational attraction between the Sun and the planets.
Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies responding to the force of gravity were conic sections. Newton showed that a pair of bodies follow orbits of dimensions that are in inverse proportion to their masses about their common center of mass. Where one body is much more massive than the other, it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body.
To read more, go here:
http://curious.astro.cornell.edu/question.php?number=467

Answer 2

As a result of Newton laws of mechanics and his gravitation law, orbits can be one of three tipes: 1) Closed orbits. They are elliptical in general, and circular as a particular case. 2) Open orbits: a) Parabollic b) Hyperbollic. Those are the orbits of comets. The type of the orbit depends on the initial conditions of the movement: position and speed. Before Newton explanation and calculations, Kepler realized that the orbits of the planets were elliptical. It was a good observational work for that time, because planets orbits are nearly circular. But Kepler referred only to planet orbits, he said nothing about comets orbits. It was Newton who explained the laws and made the first correct calculations. The above referred orbit types are valid even for the two body problem (Just Sun an a planet). When more bodies are present, orbits are slightly changed (perturbations). For a body to be in a perfect circular orbit it needs to be launched with a speed v = G * M /R where G is the gravitational constant, M is the mass of the Sun (or the central body) and R is the radious or the distance from our body to the central one. The velocity must be also perpendicular to the radious. As this is a very particular value, usually the orbit is not circular.

Answer 3

A small remark :
When, we ask in physics things like, why this is so rather than otherwise? we are essentially trying to justifiy one hypothesis which we have concieved by observing certain phenomenon.

So when you ask why planets move in ellipses rather than in circles, it is a hard one in the sense if I will tell you that if you follow this theory it will predict this result . Now if you ask me how I came to this theory, I will respond by the observations i had about the same phenomenon.

So let us start from early history, Copernicus, a genius astronomer, shattered the old belief about the Sun and the planets revolving around the earth. This was a major breakthrough in astrophysics. He gave the idea of the Sun as the centre of the solar system and rest of the planets moving around it. He suggested circular path for the planets mainly because
(1) it matched with his observational data
(2) also a circle is a simple curve (this was not the main reason)

Then came TYCHO BRAHE , by whom practical astronomy had been carried to a degree of perfection before unknown, had observed all the planets through a long series of years with the greatest care, and much preseverance. From these observations, KEPLER, was able to derive three rules which planets seemed to obey as they orbited the Sun. One of these laws was that planets orbit the Sun along ellipses.

The principle of Universal Gravitation discovered by the illustrious NEWTON opened a field entirely new. He showed that all the heavenly bodies, at least those whose motions are regulated by the attraction of Sun, must necessarily, conform to the same laws, with a slight modification only which KEPLER had found for the five planets (known at the time, Venus, Earth, Mars, Jupiter, and Saturn).

KEPLER, relying upon the evidence of observations, had annonced that the orbit of every planet is an ellipse, in which the areas are described uniformly about the sun occupying one focus of ellipse. On the other hand, NEWTON, starting from the principle of Universal Gravitation, demonstrated a priori that all the bodies controlled by the attractive forces of the sun must move in conic sections, of which the planets present one form to us, namely ellipse, while the remaining forms, circles, parabolas and hyperbolas must be regarded as being also possible when the initial conditions are different.

Answer 4

The Sun is not at the center of the orbits of the planets in our solar system, but rather, to one side of it. This will help me explain:

http://en.wikipedia.org/wiki/Elliptic_orbit

The planets are drawn in towards the Sun (capture orbit), and once they have passed it, they would be inclined to continue indefinitely. However, the gravity exerted by the Sun obviously alters their path so that they travel around the Sun instead of wandering off into the wild blue (or should that be black) yonder. Throughout the entire capture orbit, the planet will have been accelerating, and once the planet reaches a high enough velocity, it breaks away from the Sun's gravity as a stone would from a sling and begins it's escape orbit.

It then travels outwards until it's inertia is once again overcome by the gravity of the Sun, whereupon it circles back and begins another capture orbit.

Answer 5

If The the moon was revolving relative only to the Earth ( that is the Earth is fixed point and not moving)its orbit around the Earth would be circular; However, because the Earth is moving relative to the Sun ,its orbit becomes eliptical because it drags in space just like a tail.
The same scenario applies to other planets.
It was Keppler that first postulated that planetary orbits are elliptical rather than circular . And from that postulate he developped Kepplers law of planetary motion.

Answer 6

For 1,500 years, people thought the path was circular, but they kept running into inconcistancies of planet movement. Kepler had access to Tycho Brahe's library of data of star locations and planetary movements. He was able to show that a planet's or a comets orbit "sweeps-out" an equal area in an equal time. He was further able to show that the only shape that could do this was an ellipse with the sun at one focus of the ellipse.

This discovery cleaned up a lot of the predictive tables of planet locations and got rid of circular orbits with add-on epicycles. Epicycles were little circles tangent to the main circle used to explain retrograde motion of the planets.

Once Kepler had laid out the elliptical orbits of the planets, retrograde motion was explained just as a "point of view" effect of the concentric ellipses of orbits with the sun always at the near focus of the ellipses.

Notice to, that this laid the ground work for Copernican, sun-centered model that we still use as our model of the solar system.

Answer 7

There is only one exact speed that will result in a circular orbit at any given distance. If you go a little shower you cannot maintain that distance and start falling toward the Sun (if you are a planet) or the Earth (if you are a satellite). But as you fall, you speed up. The result is that you end up at a lower altitude but now going too fast. When you are going too fast at a given altitude, centrifugal force pushes you away more strongly than gravity pulls you down. But as you go higher, you slow down. The result is you end up too higher but now going too slow. This repeats forever, resulting in an elliptical orbit.

Answer 8

Unfortunatly the answer tends to offer proofs for the concepts of Astrology.

Attraction between bodies interacting with each other in motion.

Like the moon causing the tides.

It come circles that's called BIAS or drag coeficcent.

It's a side effect of the interaction of speed and gravity between two bodies.

There is, for example, speculation Pluto may have been a moon of Neptune once and got pulled out of orbit as our Moon will eventually be pulled out of Earth Orbit and into a solar orbit.

Finally there is Murphy's law. There is no such thing as perfect anything.

Answer 9

Orbits were first analyzed mathematically by Johannes Kepler who formulated his results in his three laws of planetary motion. First, he found that the orbits of the planets in our solar system are elliptical, not circular (or epicyclic), as had previously been believed, and that the sun is not located at the center of the orbits, but rather at one focus. Second, he found that the orbital speed of each planet is not constant, as had previously been thought, but rather that the speed of the planet depends on the planet's distance from the sun. And third, Kepler found a universal relationship between the orbital properties of all the planets orbiting the sun. For each planet, the cube of the planet's distance from the sun, measured in astronomical units (AU), is equal to the square of the planet's orbital period, measured in Earth years. Jupiter, for example, is approximately 5.2 AU from the sun and its orbital period is 11.86 Earth years. So 5.2 cubed equals 11.86 squared, as predicted.

Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies responding to the force of gravity were conic sections. Newton showed that a pair of bodies follow orbits of dimensions that are in inverse proportion to their masses about their common center of mass. Where one body is much more massive than the other, it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body.

Answer 10

According to me the sun and the planets move in co-ordination: the gravitation or the sun controls the planets and that of the planets control the sun.
The sun and the planets are oval or egg shaped rather than a perfect sphere and so is there attraction.