Question

What process powers the sun?

Answer 1

Nuclear fusion powers Sun.

Explanation:

In the core of Sun hydrogen atoms fuse into helium atoms and part of matter is converted into energy.
for details o fusion see link http://www.universetoday.com/18707/fusion-in-the-sun/
Every second 600, million tons of Hydrogen is fused into helium.
The process is knows as proton proton chain reaction.