When the sun swells into a red giant in about 5 billion years, “Earth Might Survive Sun’s Explosion,” observational evidence of other star systems suggests. Our engulfed neighbors Mercury and Venus won’t be so lucky, but Earth has a fighting chance. Not so sure about homo sapiens, though.
When our own Sun begins to graduate from a hydrogen-burning “main sequence” star to a red giant, two effects will compete to determine the Earth’s fate, the astronomers explain. On one hand, as the Sun blows off mass in order to conserve angular momentum, the Earth will retreat to a more distant, safer orbit. But at the same time tidal forces between the Earth and the expanding star will try to drag the planet inward where it could be engulfed. The latter effect, in particular, is difficult to compute.