Solar System Question

[crsmtnallen]

First of all, sorry if my question topic was vague and did not even tell you what my question was remotely about. I just could not think of the right words for it.

I was thinking one day and something came up in my mind about the solar system. When you look at images of galaxies you see that they are flat because gravity and their rotation flattens them out. However, I was wandering why planets in solar systems have to be set out flat going around their star like galaxies do. Could planets in theory rotate around their star in completely in set orbits but at different vertexes? My knowledge of cosmology is not that detailed, I only do some amateur stuff myself, but the suns gravity on the Earth and other nearby planets is not very strong. Could planets rotate on different vertexes, but also going in the same direction as the star or the sun in our case? It could just be simple like galaxies in the universe, but I just randomly thought this up and was wandering if it had any substance to it.

[bebe7]

First of all, sorry if my question topic was vague and did not even tell you what my question was remotely about. I just could not think of the right words for it.

I was thinking one day and something came up in my mind about the solar system. When you look at images of galaxies you see that they are flat because gravity and their rotation flattens them out. However, I was wandering why planets in solar systems have to be set out flat going around their star like galaxies do. Could planets in theory rotate around their star in completely in set orbits but at different vertexes? My knowledge of cosmology is not that detailed, I only do some amateur stuff myself, but the suns gravity on the Earth and other nearby planets is not very strong. Could planets rotate on different vertexes, but also going in the same direction as the star or the sun in our case? It could just be simple like galaxies in the universe, but I just randomly thought this up and was wandering if it had any substance to it.

Many galaxies have bulges...

[Jens]

Just giving this a stab, planets in a solar system typically orbit in the same plane because of the way a solar system is believed to form, as a spinning cloud of gas. There may be another reason, too, but I'm less sure of this. When satellites orbit the earth in a north-south orbit, the orbit is unstable. So it may be that a north-south orbit is unstable in a solar system. But on the other hand, Pluto has an orbit that it quite out of the ecliptic (about 17 degrees), so they are not completely flat.

[Centaur]

First of all, sorry if my question topic was vague and did not even tell you what my question was remotely about. I just could not think of the right words for it.

I was thinking one day and something came up in my mind about the solar system. When you look at images of galaxies you see that they are flat because gravity and their rotation flattens them out. However, I was wandering why planets in solar systems have to be set out flat going around their star like galaxies do. Could planets in theory rotate around their star in completely in set orbits but at different vertexes? My knowledge of cosmology is not that detailed, I only do some amateur stuff myself, but the suns gravity on the Earth and other nearby planets is not very strong. Could planets rotate on different vertexes, but also going in the same direction as the star or the sun in our case? It could just be simple like galaxies in the universe, but I just randomly thought this up and was wandering if it had any substance to it.

Welcome to the discussion group, crsmtnallen. That’s an excellent question!

Planetesimals in an early solar system may have highly inclined orbits relative to each other. But when a pair collides and coalesces their momentum is the sum of each planetesimal’s original momentum, and the directional components of their velocities averages out. After innumerable collisions among planetesimals, the direction of the rotational momenta of the resulting planets tends to be in nearly the same direction as the net angular momentum of the original set of particles that eventually coalesced into planets. Hence the mature planets’ orbits lie in nearly the same plane. The same principle applies to the original matter in galaxies that coalesce into stars.

[chornedsnorkack]

Even if planets do not actually collide with each other - there is a lot of empty space between orbits - gravitational perturbations would tend to change orbits over time. When planets orbit at large inclination orbits, Kozai mechanism tends to change inclined orbits into eccentric orbits. Comets actually do have inclined orbits - and they often stray from their orbits into inner Solar System.

[slang]

To add to what chornedsnorkack said: the Oort Cloud, a group of comets with huge orbits , is thought to be spherical, see the image on wiki, also for orbit size appreciation. Things are not as black and white as they sometimes seem

[bebe7]

Even if planets do not actually collide with each other - there is a lot of empty space between orbits - gravitational perturbations would tend to change orbits over time. When planets orbit at large inclination orbits, Kozai mechanism tends to change inclined orbits into eccentric orbits. Comets actually do have inclined orbits - and they often stray from their orbits into inner Solar System.

Excellent point...I would also think, simply, that Celes Objs are attracted to the same Mass of the Star they are orbiting.

[crsmtnallen]

Thanks for the answers people, great to get an answer to my question!

[bebe7]

Thanks for the answers people, great to get an answer to my question!

You're welcome...

You should enjoy this link...

http://space.jpl.nasa.gov/

it's a solar system simulator.

There is a different posted in the Astronomy section with the purple alien looking smiley.

[jfribrg]

I wonder if part of the answer is in the equatorial bulge. Because of the rotation of the sun (and the planets), there is more mass near the axis of rotation (the equator). A planet or other satelite that is not on the equatorial plane would experience a very small but continuous torque that over a long period of time would cause the planet to align itself near the plane.

In thinking about this, I'm not sure how much the outer planets could be influenced in this manner, although the gravity of Jupiter may have the same effect as the equatorial bulge of the Sun.

Without doing any calculations, here is my thought on the process:

1)Star begins to form from the gas in the nebula

2)As the matter coalesces, it starts to spin due to conservation of angular momentum.

3)Coalesced matter forms a bulge and other matter is nudged toward the axis of rotation (the equator)

4)Jupiter and other planets form near the axis and the remaining matter migrates in the direction of the equator because of the gravitational attraction of the matter that is already there.

5) When everything settles down, there is very little matter except what is on the equatorial plane of the Sun. Oddballs like Pluto which are not on the plane are demoted from planet status because they dont conform to the rules. They are also so far away from the mass of the solar system that they are not influenced as much by the equatorial masses.

[chornedsnorkack]

I wonder if part of the answer is in the equatorial bulge. Because of the rotation of the sun (and the planets), there is more mass near the axis of rotation (the equator). A planet or other satelite that is not on the equatorial plane would experience a very small but continuous torque that over a long period of time would cause the planet to align itself near the plane.

A small but continuous torque would mostly cause precession of the plane of orbit.

[mugaliens]

A small but continuous torque would mostly cause precession of the plane of orbit.

Exactly - with the value of the torque being proportional to the inclination of planetary orbit. The result is that the torque precesses the plane of orbit into the same plane as the Sun's equatorial bulge.

[chornedsnorkack]

Exactly - with the value of the torque being proportional to the inclination of planetary orbit. The result is that the torque precesses the plane of orbit into the same plane as the Sun's equatorial bulge.

Not really. The torque of Moon and Sun on Earth equatorial bulge precesses the plane of Earth rotation around, not into the plane of the eclipse.