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Originally Posted by Aoie_Emesai
If I remember correctly; Gravity exist everywhere, but it dissipate over long spans of space (from like point A to point B, ex. Earth to Alpha Centauri). Would the gravity of the Sun (which probably the only unnegligible mass body inside the inner solar system) play any role in keeping the astroides within their orbits along side with all the gas giants excluding pluto because of its distance and relatively meger size. Would this also be included within it's explaination of orbital resonance? Or does orbital resonance dominate the one I gave earlier?
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Gravity reaches everywhere but its force is decreasing by the square of the distance between 2 objects. Sun's gravity basically keeps the Asteroids in their orbit. Influences from planets like Jupiter are rather negligible. But if there is enough time, negligbile forces will become observable. In space there is basically just a game of inertia vs. forces of all kinds (there is no air resistance or something like that).
The orbit of a space object is basically dependend on 2 main attributes, its absolute velocity (absolute as in tangential velocity to sun) and its elliptic barycenter. The higher the velocity, the higher is the orbit. If the elliptic barycenter is very off centric, the objects distance to the sun will increase and decrease very much within one orbit-cycle. The same goes for the relative velocity of the object (if it draws closer to the sun it accelerates, and decelerates when moving away from sun).
Objects with a very centric elliptic barycenter are considered to be more stable, because tiny changes regarding their velocity vectors do not alter much the orbit. Objects with a very off centric elliptic barycenter have much less stable orbits, their orbits can be heavily influenced, when such objects are in their "far away from sun" part of their orbit.
The stabilty of an objects orbit is basically dependend on its inertia, its gravity, and its distance to other sources of inertia, gravity.
For example objects with much inertia, will influence the orbit of objects with less inertia more, than it is the other way around. The more gravity a object has, the stronger it will interact with other sources of gravity.
Why do the debris in the asteriod belt do not agglutinate? The debris are solid, and of different size, very little changes in gravitational forces, can alter their orbit enough to collide with other debris. Since they are solid objects, they rather bust and bounce. If it was gooey substance both objects would intermix more and go through each other, thereby absorbing each others energy (resulting from the kinetic energy based on their different velocity vectors and mass). A gooey substance is able to rearrange on melocule level, so there will always be a spherelike shape after enough time of reballancing the local gravitational barycenter (molecules have rather high friction).
If solid objects were able to stick to each other (without busting or bouncing off), they'ld still have no chance to reballance their local gravitational barycenter. That leads to further erosion of the two objects until they are even smaller debris.
So over a longer period of time, big solid debris become small debris, and they will spread out. Because all the tiny gravitational outside influences will make them rebounce more and more chaotically (since they cannot absorb impact energy in small amounts over time (like the gooey objects), they rather reflect it by busting and rebouncing).
Thatswhy even negligible forces have so much influence (espacially on solid debris) over time.