The sun is the most important energy source on Earth. It provides our daily warmth and light and the rotation and orbit of the earth turn its steady output into fluctuating day and night, summer and winter. Solar energy powers the growth of all trees, grasses, herbs, crops and algae; it creates the clouds and powers the storms; it is the source of all hydro, photo-voltaic (PV), solar-thermal, bio-mass and wind energy; and, over geological time, it also creates coal.
