"For
decades, astronomers have worked with supercomputer simulations of the
basic laws of gravity, fluid and gas dynamics and radiation transport to
create physically consistent models of what protoplanetary disks should
look like as they evolve over time. The mechanism of planet formation
has also been explored through a variety of calculations and
physics-based models."
Now we have pictures on great clarity confirming what a solar system looks like as young planets first begin to form: