By this point, the Sun will have run out of hydrogen and the inward forces of gravity within the star will overcome the outwards pressures acting on the star.
Consequently, the Sun will start to expand and cool like an inflated balloon.
NASA estimates the red giant will be about 2,000 times brighter than the Sun is now.
But even more worryingly, the expanding star will likely envelop the innermost planets, Mercury and Venus.
And though the Earth might just stay out of the red giant’s grasp, its heat will be strong enough to scorch the planet.