<p>The rocky planet sizes between the Sun and Jupiter are small (Mercury), big (Venus), bigger (Earth), small (Mars), and unfinished (the asteroid belt). Is this just random chance or is there a theory of planetary formation that explains why, within Jupiter's orbit, more mass accumulated in the midway planetary orbits and less in the inner and outer orbits?</p>
<p>The answer to &quot;Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?&quot; question doesn't answer my question - although it might explain why Mercury&lt;Venus&lt;Earth.</p>

CC BY-SA 4.0
2024-01-03T16:26:33.183Z
Does this answer your question? [Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?](https://astronomy.stackexchange.com/questions/22448/why-are-rocky-and-small-planets-nearer-to-the-sun-whereas-big-gas-giants-are-fa)
Nilay Ghosh
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2024-01-03T16:28:05.000Z
Also see: https://astronomy.stackexchange.com/questions/29978/why-do-planets-and-satellites-in-the-solar-system-look-so-wildly-different-if-th
Nilay Ghosh
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2024-01-03T18:48:00.527Z
The sizes of Mercury, Venus, Earth, and Mars are probably mostly random, but it is thought that Jupiter is responsible for the formation of the asteroid belt.  See the Wikipedia page on asteroid belt.
eshaya
CC BY-SA 4.0
2024-01-03T19:34:01.803Z
@NilayGhosh The other questions you linked don't answer my question but were interesting. I suspect that the answer might have something to do with the sun and Jupiter taking more material out of play during the early formation of the solar system leaving less to eventually coalesce on the planets near them.
phil1008
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2024-01-03T22:36:01.607Z
Exoplanetary systems generally have architectures that are very different from our planetary system. We didn't expect this. We don't know why, but it suggests that we don't understand planetary system formation very well. There is thus no well founded answer to your question.
John Doty
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2024-01-04T04:52:26.910Z
I have retracted the close vote but let the question stay in the comments for the readers as both the questions are related.
Nilay Ghosh
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2024-01-05T02:36:11.883Z
@JohnDoty I agree that unproven theories are the best we can probably expect. Maybe theories backed up by some computer simulations? While I'm far from being on top of exoplanet research, my understanding is that we don't yet have many (if any) observations of rocky exoplanets in Sun-like systems due to the transits being so rare and the poor signal-to-noise ratio for these observations.
phil1008
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2024-01-05T12:59:23.143Z
@phil1008 Yes, but consider what we actually observe. If our planetary system's architecture was typical, it would be very difficult to find exoplanets, yet we've actually found thousands.
John Doty
<planet><solar-system>
The rocky planet sizes between the Sun and Jupiter are small, big, bigger, small, and unfinished. Is there a reason?
phil1008
# The rocky planet sizes between the Sun and Jupiter are small, big, bigger, small, and unfinished. Is there a reason?

(Asked by: username_0 on 2024-01-03)

The rocky planet sizes between the Sun and Jupiter are small (Mercury), big (Venus), bigger (Earth), small (Mars), and unfinished (the asteroid belt). Is this just random chance or is there a theory of planetary formation that explains why, within Jupiter's orbit, more mass accumulated in the midway planetary orbits and less in the inner and outer orbits?

The answer to "Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?" question doesn't answer my question - although it might explain why Mercury

**Tags:** planet, solar-system

> **Comments:**
> **username_1**: Does this answer your question? [Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther?](https://astronomy.stackexchange.com/questions/22448/why-are-rocky-and-small-planets-nearer-to-the-sun-whereas-big-gas-giants-are-fa)  
> **username_1**: Also see: https://astronomy.stackexchange.com/questions/29978/why-do-planets-and-satellites-in-the-solar-system-look-so-wildly-different-if-th  
> **username_2**: The sizes of Mercury, Venus, Earth, and Mars are probably mostly random, but it is thought that Jupiter is responsible for the formation of the asteroid belt.  See the Wikipedia page on asteroid belt.  
> **username_0**: @NilayGhosh The other questions you linked don't answer my question but were interesting. I suspect that the answer might have something to do with the sun and Jupiter taking more material out of play during the early formation of the solar system leaving less to eventually coalesce on the planets near them.  
> **username_3**: Exoplanetary systems generally have architectures that are very different from our planetary system. We didn't expect this. We don't know why, but it suggests that we don't understand planetary system formation very well. There is thus no well founded answer to your question.  
> **username_1**: I have retracted the close vote but let the question stay in the comments for the readers as both the questions are related.  
> **username_0**: @JohnDoty I agree that unproven theories are the best we can probably expect. Maybe theories backed up by some computer simulations? While I'm far from being on top of exoplanet research, my understanding is that we don't yet have many (if any) observations of rocky exoplanets in Sun-like systems due to the transits being so rare and the poor signal-to-noise ratio for these observations.  
> **username_3**: @username_0 Yes, but consider what we actually observe. If our planetary system's architecture was typical, it would be very difficult to find exoplanets, yet we've actually found thousands.  

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