Planetesimal hypothesis

The Planetesimal Hypothesis suggested the Solar System formed from material pulled from the Sun by a passing star, forming planetesimals that coalesced into planets. It accounted for the concentration of angular momentum in the planets. If true, there would be very few planets in the universe, since the close approach of two stars is so rare.
 Thomas Crowder Chamberlin and Forest Ray Moulton United States 1905 Planetesimal hypothesis

The Planetesimal Hypothesis suggested the Solar System formed from material pulled from the Sun by a passing star, forming planetesimals that coalesced into planets. It accounted for the concentration of angular momentum in the planets. If true, there would be very few planets in the universe, since the close approach of two stars is so rare.