The Earth might avoid being engulfed by the sun during its final stages of stellar evolution, according to a new study. Contrary to popular scientific projections that anticipate Earth's destruction, researchers have presented a theory suggesting the planet could potentially survive the sun's transition into a red giant and subsequent death as a white dwarf.
Approximately 5 billion years from now, the sun is expected to exhaust the hydrogen fuel in its core. This event will cause the star to expand dramatically, potentially hundreds of times its current size, transforming into a red giant. Later stages will see it become an Asymptotic Giant Branch (AGB) star before collapsing into a white dwarf.
Previous models predicted that this expansion would inevitably lead to the engulfment of Mercury, Venus, and Earth. However, the new research, published in Astronomy and Astrophysics, utilizes stellar evolution models and observations of a nearby dying star, L2 Puppis, to explore alternative outcomes.
The study's lead author, Mats Esseldeurs from the Institute of Astronomy of KU Leuven, stated that observations of sun-like giant stars currently indicate a possibility of Earth's survival. The fate of Earth hinges on the balance between two competing forces: tidal interactions and mass loss from the sun.
As the sun expands, its increased gravitational pull could draw Earth inward. Simultaneously, the star will experience a strong stellar wind, shedding significant mass. If this mass loss is rapid enough, it could weaken the sun's gravitational hold on Earth, allowing the planet to migrate to a wider orbit and escape being swallowed.
"The fate of Earth depends on a delicate balance between these two effects," Esseldeurs explained. "If tidal interactions dominate, Earth is engulfed. If mass loss dominates, Earth escapes to a wider orbit."
While the study offers a hopeful scenario for the planet's physical survival, it does not change the fact that life on Earth would cease long before the sun's ultimate demise. The sun, currently about halfway through its lifespan, will continue to increase in temperature and luminosity, rendering the planet uninhabitable for humans well before the red giant phase.
The researchers emphasized that more precise observations are needed to determine the exact rate of mass loss for aging stars, which is crucial for definitively predicting Earth's ultimate fate. The study was supported by an international team of researchers investigating the end stages of solar-like stars.