Ascientific is a scientific explanation formulated based on known facts and repeated testing.

Answer;

-The sun

Explanation;

-The Sun is the primary source of energy for the Earth.

-Plants convert light energy from the sun into chemical energy by the process of photosynthesis. Sun's heat is responsible for weather change which in turn causes wind. It can be converted to electricity by windmills etc. An important part of Water cycle is Evaporation, and hence, Sun.

-The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers, such as plants and algae, use energy from sunlight to make food energy by combining carbon dioxide and water to form organic matter.