- #1
- 59
- 0
Why is the earth's orbit elliptical? That is, what force acts on the earth perpendicular to the force of the sun, that causes the tangential accelerations characteristic of an ellipse?
Why is the earth's orbit elliptical? That is, what force acts on the earth perpendicular to the force of the sun, that causes the tangential accelerations characteristic of an ellipse?
There is indeed a tangential acceleration. Acceleration is change in velocity. For a circular orbit, the change is perpendicular to the velocity, and parallel to the radius. For an elliptical orbit, the velocity changes in magnitude, and so the acceleration has a component perpendicular to the radius.
Where am I going wrong?
Thanks.
Let me phrase my comments in another form.
Consider the two-body problem of the earth and sun, each replaced by point masses. Define let the coordinate system so that the orbit is in the x-y plane. At t=0, let the earth be at its closest distance, and moving in the y direction. Solve the equations of motion, using the initial conditions. The solution is a circular path.
The reality is that the orbit of the earth is an ellipse, with an eccentricity ?, which is a function of time. Since the fact of ?(t) is a fact that does not occur in the initial equations, there is no way to find a solution with ? ? 0.
I believe that the eccentricity is a result of the many-body problem, taking into account the large planets. There is no analytical solution to the Newtonian gravitational many-body problem. I do not have the tools to solve this problem. I wonder if any of you know about many-body calculations that result in the correct ?(t)?
No, I do not understand how a two body problem can give non-circular orbits, for then the result is more than the input.
It is not possible to get more out of a set of equations than the stuff that goes into the equations and initial conditions.
I think I got it. Consider my setup: A mass m is orbiting in the xy plane. At time t=0, the mass is at (x,0). It has a velocity v in the y direction. This is the given. Question: What will the orbit be?
Can one write the eccentricity as a function of velocity - velocity(circle), derived from the equation of motion?
My level: Ph.D. theoretical physics.
BTW, how do I write subscripts in these messages?
ok fine ! earth is farthest in july and not in december but again it has a co-relation with galactical gravitational force ! as earth aligns itself with the center of galaxy and sun twice in July and December the farthest and almost nearest and aligns with Solar system's locus/path in April and october ! dont you still see a co-relation in earth's elliptical orbit behaviour because of galaxy or it is merely a "co-incidence" !!!! you need to empty the cup ( filled with so many thumb rules) before putting the new principles. we're not kids , if a lesson is learnt it is universal every law/principles has some conditions but putting/converting into a predicate logic all the conditions need to be considered as well plus open up mind to at least consider if not adapt in entiriety . philosophy and science go hand in hand. Phd in science !! uh
No, it doesn't. The Earth's orbit precesses due largely to the gravitational influence of the other planets. (General relatively also plays role here, but a much smaller role than the simple Newtonian gravitational attraction by the other planets.) With respect to the fixed stars, the Earth's apsidal precession is one revolution per 112,000 years. Compare this to the rate at which the solar system orbits the galaxy: one revolution per 225 million years.ok fine ! earth is farthest in july and not in december but again it has a co-relation with galactical gravitational force !
No, they don't.philosophy and science go hand in hand.
Are you claiming to have a "Phd in science"? If so, I call BS.Phd in science !! uh