What substances were found in the innermost regions (within about the inner 0.3 au) of the solar system before planets began to form? view available hint(s) what substances were found in the innermost regions (within about the inner 0.3 ) of the solar system before planets began to form? nothing at all only rocks and metals only hydrogen compounds only hydrogen and helium gases rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form?