What else contributes to earth's life support besides the sun?

Answer 1

Good question - the Sun provides the energy upon which most life on Earth depends. However, life on Earth also depends on water, and some combination of oxygen, sulfur, carbon dioxide, etc. The rotation of the Earth also plays a role, as this allows for the energy of the Sun to get to all parts of the surface of the Earth.

One can argue that the interior of the Earth also is important - the geomagnetic field is produced inside the Earth, which provides some protection from cosmic rays and the solar wind. Important elements for life also come out of the interior of the Earth, and plate tectonics allows for the renewal of the Earth's surface.