Why do planets of our solar system orbit in rings not spheres?

In summary, the reason why the asteroid belt outside of Mars is a ring and the planets all seem to orbit the sun on a similar plane is due to the initial non-zero angular momentum of the molecular cloud from which the Sun and planets formed. As more mass fell into the protosun, it began influencing the rest of the cloud gravitationally, causing particles with non-zero angular momentum to orbit the star. These initial orbits resulted in collisions that eventually formed a proto-planetary disk, from which the planets and asteroids formed. This phenomenon is also seen in Saturn's rings and is due to the gravitational pull of nearby objects equalizing.
  • #1
Schoomy
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I was looking at this link: http://en.wikipedia.org/wiki/File:Universe_Reference_Map_%28Location%29_001.jpeg" [Broken] and wondered to myself why the asteroid belt just outside of Mars is a ring...as opposed to a sphere.

Then I thought, why do all the planets seem to orbit the sun on a similar plane. For example, Earth and Mars have similar orbit planes. Why wouldn't one have a plane of orbit 90 degrees crossed of another?

I couldn't find a good answer online...it's probably simple! :p

Note: I say "sphere" but obviously it can only orbit in a ring. Just imagine, however, that each orbit path left a tracer line behind it. Their orbits wouldn't create spheres over a long timespan would they? Hope that makes sense!
 
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  • #2
Another thought: this is probably a similar phenomenon to why Saturn's rings are on a very similar plane, yes? Does it have to do with the gravitational pull of nearby objects equalizing?
 
  • #3
The molecular cloud from which the Sun and planets formed had some initial non-zero angular momentum. The protosun formed about some local concentration of mass. As more and more stuff fell into this protosun it began influencing the rest of the cloud gravitationally. The atoms/molecules with little angular momentum fell into the forming star. The stuff with non-zero angular momentum began orbiting the star. These initial orbits would have been quite random in nature, resulting in lots of collisions. The relative velocity between two particles in roughly the same orbit is quite small compared to the relative velocity between two particles in quite different orbits. The end result of all these collisions was to make the particles coalesce into a proto-planetary disk about the star. The planets (and asteroids) formed from this proto-planetary disk.
 

1. Why do planets of our solar system orbit in rings not spheres?

The planets in our solar system orbit in elliptical paths, not perfect circles. This is due to the fact that the planets have both a forward motion caused by the initial energy of their formation and a gravitational pull towards the sun. These combined forces create an orbit that is closer to an ellipse than a perfect circle.

2. What causes the rings around planets in our solar system?

The rings around planets in our solar system are caused by debris, such as dust and ice, orbiting around the planet. This debris is held in place by the planet's gravitational force and can form rings due to the planet's rotation and the gravitational forces of nearby moons.

3. How do the rings around planets form?

The rings around planets form when small particles of debris, such as dust and ice, collide and stick together due to electrostatic forces. Over time, these particles continue to collide and grow in size, eventually forming the rings that we see around planets in our solar system.

4. Why do some planets have rings while others do not?

Some planets have rings while others do not due to a variety of factors, including the planet's size, distance from the sun, and composition. For example, gas giants like Saturn have large and visible rings due to their strong gravitational pull and large amounts of debris in their orbit. Smaller, terrestrial planets like Earth do not have rings because their gravity is not strong enough to hold debris in orbit.

5. Will the rings around planets in our solar system last forever?

No, the rings around planets in our solar system will not last forever. Over time, the rings will continue to lose particles due to collisions and gravitational forces from nearby moons. Eventually, the rings will dissipate and disappear, either falling onto the planet's surface or being pulled into the planet's atmosphere.

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