Will Earth survive the Sun's death? New study suggests it might.
A new study suggests Earth might survive the Sun's death when it becomes a red giant in about 5 billion years. Instead of being engulfed, the planet could migrate outward as the Sun loses mass, potentially avoiding destruction—though its surface would become uninhabitable.
Background
- In about 5 billion years, the Sun will exhaust its hydrogen fuel and swell into a "red giant," eventually engulfing the inner planets — a standard prediction of stellar evolution.
- This study (led by KU Leuven astronomers) revisits how much mass the Sun will lose as it becomes a giant. More mass loss means its gravitational pull weakens, causing planetary orbits to expand.
- The key variable is the "efficiency of dynamical friction" — how orbiting bodies like Earth transfer energy to a star's outer layers. Using new models, the team found that Earth's orbit might widen faster than the Sun expands, possibly saving it from being swallowed.
- Even if Earth survives the red giant phase, its surface will be baked to uninhabitable temperatures long before. The finding is about orbital survival, not habitability.
- The result is a revision of a long-held assumption; most prior models predicted Earth would be vaporized inside the Sun's outer envelope.