Here’s why humanity won’t survive our own Sun. The Sun looks calm from Earth, but it’s slowly changing. As hydrogen in its core is fused into helium, the Sun heats up and becomes brighter over time. In about 1 billion years, Earth will enter a runaway greenhouse state: the oceans evaporate, the atmosphere collapses, and life ends long before the Sun physically touches our world. But the true ending arrives 5 billion years from now, when the Sun expands into a red giant large enough to erase Eart

The Sun’s Life Cycle Explained - Birth, Power, and the End of Earth