The Sun may not engulf Earth after all, scientists say

Earth may avoid being swallowed by the expanding Sun in five billion years, according to a study published in the journal Astronomy & Astrophysics. Researchers from the University of Leuven and CEA Paris-Saclay found that stellar mass loss could push the planet outward, countering the gravitational pull that previously suggested Earth’s inevitable destruction.

Will the Sun swallow the Earth?

Current research suggests Earth’s fate depends on a “delicate balance” between two opposing forces. As the Sun exhausts its hydrogen and expands into a red giant, its increasing gravitational pull creates tidal waves within the star that could drag Earth inward. However, the Sun also loses significant mass through stellar winds, which pushes planets further away.

Mats Esseldeurs, lead author and astrophysicist at Belgium’s University of Leuven, stated that if the Sun’s mass loss outweighs the tidal interactions, Earth will escape into an orbit larger than the star’s radius. While scientists previously believed tidal forces would dominate, new modeling indicates that tidal dissipation is lower than earlier estimates suggested.

How does the Sun’s expansion process work?

The process begins when the Sun burns through the hydrogen in its core. This triggers two massive expansion phases. First, it swells into a red giant. Once its helium is spent, it enters the AGB star phase.

During these phases, the Sun’s surface approaches the inner planets. This proximity creates intense tidal interactions. According to the study, these forces act similarly to how the Moon’s gravity creates tides in Earth’s oceans, though on a much more destructive stellar scale.

Which planets will survive the solar expansion?

The survival of the solar system depends on the distance of each planet from the expanding fireball. According to the new modeling, Earth and Mars are likely to escape a death spiral into the Sun.

Mercury and Venus won’t be so lucky. The researchers concluded these two planets will be inexorably swallowed by the star. Once the expansion ends, the Sun will transition into a white dwarf—an extremely dense, cooling remnant that no longer supports fusion reactions.

Why does this change previous scientific predictions?

For years, the consensus leaned toward Earth’s destruction. This was based on relatively simple descriptions of tidal dissipation. The shift in prediction comes from 15 years of advances in tidal modeling, which showed that the energy dissipating at the star’s surface is lower than previously calculated.

This means the “push” from the Sun’s mass loss is more likely to win the tug-of-war against the “pull” of gravity. While this saves the planet’s physical structure, the study notes that all life on Earth will be wiped out long before this process even begins.

Quick Comparison: Old Theory vs. New Research

Frequently Asked Questions

When will the Sun expand?
This process is expected to occur in approximately five billion years.

Will humans survive the red giant phase?
No. The study indicates all life on Earth will be wiped out long before the Sun begins its final expansion.

What is a white dwarf?
A white dwarf is the dense, dim core left behind after a star like the Sun sheds its outer layers. It no longer performs fusion and slowly cools over time.