What makes the orbits of the planets ellipse?

Question

Is it possible , that it may just cause of the gravitional force at the center of our milky way...or maybe because of the velocity of our sun to the center of milkyway that affects the orbit of the planets..

Answer 1

At first glance it may seem odd that a force such as gravity, which pulls the planets straight in toward the center of mass, should result in elliptical orbits! But in fact it is quite straightforward to understand why this should be so.

It is certainly possible to set up a satellite so that it has a circular orbit (a circle is just an ellipse whose foci coincide). Gravity can only pull in the direction toward the planet. The inertia of the satellite makes it want to travel in a straight line, but if it does so, its velocity is no longer perfectly perpendicular to the pull of gravity, so gravity pulls it in; this will remove part of the velocity, but as the satellite is also falling inward, it gets a new component of velocity due to the acceleration of gravity. In a circular orbit, we know that the ground speed is constant, so these two effects must perfectly cancel one another out to leave the speed of the satellite unchanged. Now imagine that we fire the satellite's boosters so that its ground speed increases. Now the desire of the satellite to go straight is stronger, so the two effects do not cancel perfectly, and the ground speed will vary. You can see how this corresponds to an elliptical orbit, and how a planet orbiting the Sun behaves in the same way. (Of course, planets have no boosters, but think about what effect the initial velocity of the planet due to the process of its formation would have--what happens if a planet is formed with only a small initial velocity, far from the Sun, or if it is formed with a large velocity, very near to the Sun? What happens if the inital velocity of the planet is zero?).

Answer 2

It takes 2 forces to create an ellipse from a center.

If the Planets only was under influence from the Sun, the orbit of the Planets much likely would be a circle.

Therefore there must be an extrasolar system power which affects the Solar System and the orbiting Planets.

- Unfortunately, the planetary orbiting motions and the description of the extra solar system power influence on the Solar System, cannot be explained satisfactorily unless you skip the very idea of the Newton and Einstein Laws of Gravity.

Answer 3

No, it's just the attraction of gravity between the sun and the planets.  Has nothing to do with the milky way or the sun's velocity within it.

Answer 4

The circle is not the "natural" shape of an orbit.  Orbits are naturally conic sections.  Closed orbits are ellipses, one form of conic section.  A circle is also an ellipse, so a circular orbit is just an ellipse with a degenerate eccentricity.  Left alone, orbiting objects would not naturally "settle" into a circle.

To understand why an ellipse makes a stable orbit, you have to consider that orbits are defined by exactly two effects:  momentum and gravity.  The first response gives an excellent description of momentum and gravity.  Another set of effects that balance in a stable orbit, which also derive from those two basic effects, is kinetic and potential energy.  Potential energy derives from altitude; kinetic energy derives from motion.  In a stable orbit, the combination of those two will be the same at every point along the orbit.

That doesn't mean each component has to be the same at every point; just the combination of them.  So at the high point of an elliptical orbit, there is a lot of potential energy (high altitude), but less kinetic energy (the orbiter moves slower).  At the low point, potential energy is low and kinetic energy is high (the orbiter moves faster).  The fact that orbiting objects change velocity along the orbit makes orbits stable even when the altitude changes.