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<Venus<Earth.

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    $\begingroup$ Does this answer your question? Why are rocky and small planets nearer to the Sun whereas big, gas giants are farther? $\endgroup$ Jan 3 at 16:26
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    $\begingroup$ Also see: astronomy.stackexchange.com/questions/29978/… $\endgroup$ Jan 3 at 16:28
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    $\begingroup$ 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. $\endgroup$
    – eshaya
    Jan 3 at 18:48
  • $\begingroup$ @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. $\endgroup$
    – phil1008
    Jan 3 at 19:34
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    $\begingroup$ @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. $\endgroup$
    – John Doty
    Jan 5 at 12:59


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