Earth May Escape Engulfment by the Sun, New Study Suggests
A study published in Astronomy & Astrophysics on Friday (June 19) has reassessed the likelihood of Earth being engulfed by the Sun when it expands into a red giant star in approximately five billion years. The research suggests that lower-than-previously-estimated tidal dissipation within the dying Sun may allow Earth to move into a wider orbit, potentially avoiding destruction.
The study was led by Mats Esseldeurs of the University of Leuven, Belgium. Researchers used stellar evolution models and observations of the star L2 Puppis—an analog for the Sun's future state located 200 light-years away in the constellation Puppis—to simulate the competing forces of tidal pull and solar mass loss.
Key Findings
- The study analyzed tidal dissipation in giant stars, concluding that it is lower than previously estimated.
- Earth's fate is determined by the balance between tidal forces (which pull Earth inward) and solar mass loss (which pushes Earth outward).
- Under the new model, Earth and Mars may avoid being engulfed, while Mercury and Venus are predicted to be consumed by the Sun.
- The Sun will eventually become a white dwarf.
Background
As the Sun depletes its hydrogen core, it will expand into a red giant and later into an asymptotic giant branch (AGB) star. This expansion generates tidal forces that would typically pull planets inward. At the same time, the Sun will lose mass via stellar winds, reducing its gravitational grip and allowing planets to drift outward.
Previous research on Earth's fate yielded conflicting results due to different assumptions about mass loss, tidal forces, and planetary interactions. Observations of white dwarf systems show both intact planets and rocky debris, providing ambiguous evidence.
The star L2 Puppis is losing an estimated one-millionth of a solar mass per year. According to the study, the primary uncertainty in predicting Earth's fate is the total amount of mass the Sun will lose during its giant phases.
Expert Statements
"Earth's fate depends on a delicate balance between these two effects." — Mats Esseldeurs
Co-author Stephane Mathis noted that "a better understanding of tidal physics and mass loss constraints allow us to say that Earth could move away from the Sun."
Future Research
The European Space Agency's PLATO mission, scheduled for launch next year, aims to detect planets around aging stars. Researchers indicate this data could improve predictions regarding Earth's long-term fate.
Note: All life on Earth is expected to have ended long before these stellar events occur.