How are solar systems formed?
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Q. How are solar systems formed?
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A. Space everywhere contains "Oort Soup", a mix of planetesimals and planets of every size. Over time, these may aggregate together. When an aggregation reaches the mass of a star, this forms the beginning of a solar system.
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Q. What's the lower limit of a star's mass?
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A. It's about 7.5% of the mass of our Sun.
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Q. What qualifies a body of this mass to be a star?
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A. That's the minimum mass for nuclear fusion to begin at its core.
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Q. What forms first in a solar system, the star or its planets?
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A. Surprisingly, the planets exist first, as components of the Oort Soup. When aggregation leads to a new star, this has to normalize the motion of other bodies in its vicinity.
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