What is the birth of the solar system?

A collapsing intersteller cloud.
The solar system was probably born from a nebula, although by now that particular nebula probably no longer exists. Also, any other objects born in it have been moving through the galaxy in their own orbits and may now be nowhere near us.
A small to medium sized cloud of interstellar gas and particulates that coalesced from the remnants of one or more 'local' nova and or supernova explosions.