Overview
- A peer‑reviewed study by KU Leuven and CEA Paris‑Saclay published in Astronomy & Astrophysics finds the outcome of Earth’s orbit during the Sun’s red‑giant and AGB phases depends on a fine balance between inward tidal friction and outward orbital expansion from stellar mass loss.
- The team used revised tidal‑dissipation models and observations of the evolved star L2 Puppis to run simulations that, under higher AGB mass‑loss rates, push Earth outward enough to avoid engulfment.
- All simulations consistently predict that Mercury and Venus will be swallowed by the expanding Sun and that Mars will most likely remain safely outside the engulfed zone.
- The dominant remaining uncertainty is how much mass the Sun will lose during the AGB phase because different measurement methods give widely varying rates, so better observations are required to make a decisive prediction.
- Even if Earth’s orbit survives, the planet will be uninhabitable long before the Sun becomes a red giant, so orbital survival would not preserve life or surface habitability.