Every Way The Sun Will Die Explained In 16 Minutes

Brightening Sun The Sun is already dying. It has been dying since the day it formed, 4.6 billion years ago, and the process is visible right now in its brightness. The Sun today is roughly 30 percent brighter than it was at birth. It did not flare up overnight. It has been climbing slowly and steadily, and today it brightens by about 1 percent every 100 million years. When the Sun was young it was so dim that it should, by rights, have left the early Earth frozen solid. It did not, and why the young Earth stayed warm under a faint young Sun is a puzzle astronomers still chew on. The cause of the brightening is buried in the core. The Sun makes its energy by fusing hydrogen into helium, and with every reaction the core fills a little more with helium ash. Helium is heavier than hydrogen.