The configuration of planetary orbits in the solar system has led to the theory that the planets were formed through processes of coagulation in a flattened differentially rotating gaseous disc that was formed at the same time as the sun.
The recent discoveries of the high incidence of gaseous discs around
young stars, remnant dust discs around main sequence stars, and
planets with masses comparable to that of Jupiter outside the solar
system, indicates that planetary formation through such processes is
a common phenomenon in nature.