Is our solar system typical ?

This is a very interesting question, whose answer is currently untestable. BUT, there are some general features of our solar system that ought to be common. First, the most distant planets in every solar system ought to be gaseous and icy bodies because ices and gases will be the most common compounds present under low temperatures in these distant regions. Because planets probably grow in size by sweeping-up material along their orbits, the more distant planets ought to be bigger than the inner planets since the volumns of space the distant planets can sweep out is vastly larger than what is available to the inner planets. The early phases of stellar evolution seem to require huge winds of gas blowing through the inner solar system. This would shut-down the planet accreting process and blow-off all lightly-held material from the inner planets. It wouldn't surprise me that inner planets are all dominated by rocky bodies. Some may have thick secondary atmospheres outgassed from vulcanism. For the outer planets, it also wouldn't surprise me that ringed worlds like Saturn would be common. Jupiter, Saturn, Uranus and Neptune all have rings. I would expect in other solar systems, even more spectacular ringed systems might exist.

As for the number of planets and their masses, that depends on the details of when and where they were formed. Some solar systems might only have a single massive planet, one the verge of being a binary star system, others might have asteroidal rubble.


Copyright 1997 Dr. Sten Odenwald
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