Eli5: In our solar system, why are all of the gas giants past the meteor belt? Is it just a coincidence? Do other solar systems have similar organizations, with some rocky planets, a meteor belt, then gas giant planets, or is ours unique?

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In: Planetary Science

Answer 1

I assume you mean the asteroid belt. Meteors are things that hit Earth.

And the asteroid belt isn’t unique even in our own solar system, see the [Kuiper belt](https://en.wikipedia.org/wiki/Kuiper_belt). It’s just less known because it’s more recently discovered, and more recently discovered because it’s farther from both the sun and Earth, so much less light makes it to those objects and much less of the light that does make it to the objects makes it back to Earth.

Answer 2

There are no reasons gas giants cannot exist inside an asteroid belt, in fact there are asteroid belts beyond Neptune.

The reason however that our Solar system is probably quite typical are:

– Large gas planets cannot exist too close to the sun for too long. Due to the effects of tidal forces on the gas giant, a gas giant will slowly become tidal locked and then lose matter to the star’s gravitational pull and eventually be consumed by the star if it is too close.

– Similarly rocky planets like our own, if formed too close to a gas giant will likely be gravitationally captured by the gas giant and become a moon of that gas giant rather than a planet orbiting the central star.

Combining these two facts gives you that the planets closer to the star tend to be rocky, as solid planets are less impacted by the tidal effects than gaseous planets and rocky planets further away tend to end up being the moons of gas giants rather than planets of their own accord.

Answer 3

There is no reason a solar system needs to be structured the way ours is. For a long time the most common type of planets we’d discovered in other solar systems were large gas giants, bigger than Jupiter, near their stars. However, this is partially because those were the easiest to see with the first types of telescopes used to find them. Since then planets a bit smaller than Neptune have been the most common type discovered. [A study released last year](https://www.scientificamerican.com/article/we-live-in-the-rarest-type-of-planetary-system1/) categorized solar systems we’ve studied by the sizes of their planets and their order, and found ones like ours with the inner planets being smaller than the outer planets were actually the least common. As far as I know, we have not yet developed a way to see asteroid belts in other solar systems, but it is likely they are fairly common.