Since this is not my area of expertise, I searched Google under the key words "gravity 'solar system' movement" to get these possible sources:
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In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps. Thanks for asking.
what are the role of the electrons in ionic bonds,covalent bonds and metallic bonds?
I don't know what to say here. Of the forces known to exist in nature
gravity, electrical/magnetic, nuclear strong, and nuclear weak force, gravity is the only force possible.
If you were trying to explain planetary motion, then the orbits result because the force of gravity is just sufficient to change the motion of the planet to keep it in the same orbit. If it were less, the planet would hurl into space, if it were greater, the planet would fall into the Sun. The why of this is in the language of mathematics of Newtons's laws, and before him, Kepler's laws, and numerous Greeks who studied the laws and math of conic sections.