The answer is very simple. The nuclear fusion process that takes place in the central region of the sun converts hydrogen into helium plus energy. One thousand grams of hydrogen produces 993 grams of helium with 7 grams of mass being converted into energy via E=mc2. The sun formed from a massive cloud of gas about 5 billion years ago. It took about 50 million years to form. When it was a newborn star, it had enough hydrogen fuel for 10 billion years.
Definition of crunch. 1  intransitive verb. 2  1 : to chew or press with a crushing noise. 3  2 : to make one's way with a crushing noise. 4  transitive verb. 5  1 : to chew, press, or grind with a crunching sound. 6  2 : process; especially : to perform mathematical computations on crunch numbers.
Grinding or crunching are common symptoms of cartilage problems. If the cartilage is damaged -- a condition called chondromalacia -- a crunching sensation is often felt by placing the hand over the kneecap and bending the knee. A similar grinding sensation may be felt with knee arthritis.