Mark Garlick/Science Photo Library
When I found out the date of the end of the Earth, everything seemed so simple. Five billion years from now, the solar system will have changed dramatically. Instead of the gentle presence we are accustomed to, the sun will become a behemoth, hundreds of times larger than it is today. In the process, it will wipe out the rocky inner planets, including our own.
Or will it be? We recently witnessed the death stages of another star for the first time. And miraculously, it seems some planets will be able to survive this apocalyptic era. Observations like these call into question the story of how the Earth will die, and give us hope that somehow the Earth may outlast the Sun. Even if it doesn’t, all is not lost. The study also provides clues as to where humans might best seek refuge.
How does the sun die?
The sun is powered by nuclear fusion. In nuclear fusion, hydrogen atoms fuse into helium, releasing a huge amount of energy in the process. However, the fate of our star is determined by one fact. This means that the supply of hydrogen is limited. As this energy begins to deplete, in about another 5 billion years, the Sun’s internal structure will change and it will expand to about 200 times its current size. It will change from the current yellow dwarf to a red giant. After another billion years, the star shrinks and expands again, before disappearing and becoming a stellar corpse called a white dwarf.
As it grows…
