How are the planets in our solar system arranged in a specific order around the Sun, and how does their size play a role in determining that order?
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The material in the planets now used to be in a big dust cloud surrounding the star. Stuff clumped together into larger objects.
So the planets are where they are now just because they’re far enough apart to not easily get disturbed into colliding with each other, and they’re the size they are because that’s how much stuff was in the area. Though the gaseous hydrogen and helium that would have been on the inner planets got blown off by the solar wind. The gas giants have enough gravity that they can hold onto those lighter gases, which are the most common elements in the overall universe.
The main equation for circular motion is a = v^2 /r .
As the acceleration towards the sun is the gravitational field strength where g = GM/r^2 .
Replacing g for a as the acceleration is the field strength, you get v^2 = GM/r. G and M are constants, one the gravitational constant and one the mass of the sun. So r is inversely proportional to v^2 .
Notice mass of the planet is not involved, just the velocity. I hope this helps.
We don‘t know, it might be pure chance.
There are other solar systems where the gas giants orbit their stars at an extremely close distance, much closer than Mercury orbits the Sun. We call those planets Hot Jupiters: https://en.m.wikipedia.org/wiki/Hot_Jupiter
We have also found solar systems without any gas giants. One example is TRAPPIST-1, a star that is orbited by seven Earth-sized planets: https://en.m.wikipedia.org/wiki/TRAPPIST-1
In short, there is no evidence so far that the planetary arrangement of our solar system is common or follows a certain logic. There is, however, a theory stating that life as we know it could only form because we live in a solar system with our arrangement. Jupiter catches a lot of comets and asteroids that could lead to extinction events on Earth.
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