The sun dying is one of those ideas that seems so improbable that it's not even worth thinking about. But fast forwarding to one billion years from now and you would think otherwise; that's when the sun will have used up all the hydrogen fuel in its core, forcing it to burn at its surface. That's no good news for planet Earth, as the increased radiation will evaporate all of Earth's water, essentially creating a global desert.
Now jump five billion years ahead: at this point the dying sun will literally be melting mountains and there will be no life left on our dear planet. By 7.5 billion years from now, the sun will consume the planet entirely - bye bye world! Talk about an existential crisis.
But some scientists aren't about to let this apocalyptic ending come crashing and burning (quite literally). Through a technique called Gravity Assist, which relies on Newton's Law, "To every action there is an equal and opposite reaction," physicists think that it may be possible to incrementally (over millions of years) move the Earth's orbit farther from the Sun. This method would require using an asteroid or something of equivalent mass (approximately 10^19 kg) to gradually (every 6,000 or so) increase the distance of the Earth's orbit around the Sun to 225 million km. However, that's risky business because it could greatly disturb other planets' orbits in our solar system, increase the spin of Earth, and potentially destroy the moon. Uh oh. The good news is we have a lot of time to take action!