What will happen when the Sun dies?
The Sun will not live forever. In the very distant future, it will grow into a red giant and then shrink into a white dwarf. Life on Earth will vanish. There's nothing we can do about it, except move somewhere else.
When the Sun exhausts its store of nuclear fuel, some 5 billion years from now, it will evolve into a bloated red giant, gobbling up Mercury and Venus, and scorching the Earth. After ejecting its outer layers in the form of a colourful planetary nebula, the Sun will then be compressed into a tiny white dwarf star. But much earlier, the Sun's temperature will gradually rise. Less than a billion years into the future, Earth's oceans will start to boil away. It's unlikely that mankind will still be around by then, so it is better to worry about other short-term problems that threaten our planet's habitability.
Life on Earth is not possible without the light and heat from the Sun. So when the Sun dies, that’s bad news. Luckily for us, it won’t happen until a few billion years from now.