Answer:
The sun's energy comes from thermonuclear fusion reactions.
Explanation:
Due to the Sun's strong gravitational pull, hydrogen atoms fuse, resulting in helium atoms. During this process, tremendous amounts of energy are released, or the energy of the Sun.
Since both heat and work can be measured and quantified, this is the same as saying that any change in the energy of a system must result in a corresponding change in the energy of the surroundings outside the system. In other words, energy cannot be created or destroyed.