Will Earth survive the Sun's death? New study suggests it might. — Institute of Astronomy

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A delicate tug-of-war

As the Sun evolves into a red giant, two competing processes determine Earth's fate. On the one hand, the Sun will expand enormously, increasing the gravitational tidal forces that tend to pull Earth inward. On the other hand, the Sun will lose a large fraction of its mass through a stellar wind. As the Sun becomes lighter, Earth's orbit gradually moves outward.

"The fate of Earth depends on a delicate balance between these two effects," says lead author Mats Esseldeurs, researcher at the Institute of Astronomy of KU Leuven. "If tidal interactions dominate, Earth is engulfed. If mass loss dominates, Earth escapes to a wider orbit."

Previous studies often concluded that Earth would eventually be consumed by the Sun. However, many of these studies relied on simplified descriptions of tidal interactions inside giant stars.

A schematic evolution of the Sun as it goes through its giant phases. The image showed the Sun as it is today, going through its two giant phases, before ending its life as a white dwarf. The study showed that Mercury and Venus will be engulfed by the expanding Sun, but Earth and Mars survive, ending up in a wider orbit. Sizes and distances are not to scale.

Looking inside the future Sun

The new research uses state-of-the-art calculations of tidal dissipation based on the internal structure and dynamics of evolved stars. These models were developed by the research team in earlier work and are based on first-principles calculations rather than simplified approximations. Using these updated prescriptions, the researchers found that tidal interactions are weaker than previously assumed. As a result, Earth remains farther from the Sun during the giant phases, significantly increasing its chances of survival.

In the simulations, Mercury and Venus are inevitably engulfed by the expanding Sun. Earth, however, survives both the giant phases, ending up in a wider orbit around the white dwarf remnant that the Sun will eventually become.

A giant uncertainty: stellar mass loss

Despite this encouraging result, the story is not yet settled. The researchers found that the final outcome depends on how rapidly the Sun loses mass during its last giant phase. Unfortunately, these mass-loss rates remain a poorly understood aspect of stellar evolution.

To investigate this uncertainty, the team turned to L2 Puppis, a nearby evolved star often regarded as a glimpse of the Sun's future. Using this observational estimate, Earth will move outward just enough to survive.

"The largest uncertainty no longer comes from the tidal calculations, but from how much mass the future Sun will lose," says Mats Esseldeurs. "Observations of Sun-like giant stars currently point towards Earth's survival, but we need better observations before we can be certain."

Learning about the future by observing distant stars

The study highlights how observations of evolved stars can provide clues about the distant future of our own Solar System. Upcoming facilities and missions will discover many more planets around giant stars, allowing astronomers to test models of planetary survival on a population scale.

Although life on Earth will become impossible long before the Sun reaches its giant phases, the planet itself may endure. Whether Earth ultimately survives or not, the answer lies in understanding the complex physics of ageing stars, a problem astronomers are only now beginning to unravel.

Original journal article: "The fate of Earth during the Sun's giant phases. New constraints from ab initio tidal modelling and AGB mass loss", M. Esseldeurs, S. Mathis, L. Decin, Astronomy & Astrophysics, Forthcoming article, Received: 23 April 2026 / Accepted: 31 May 2026, https://www.aanda.org/10.1051/0004-6361/202660576

Funding acknowledgement: M. Esseldeurs, S. Mathis and L. Decin acknowledge support from the FWO grant G0B3823N. M. Esseldeurs and L. Decin acknowledge support from the FWO grant G099720N, the KU Leuven C1 excellence grant MAESTRO C16/17/007, the KU Leuven IDN grant ESCHER IDN/19/028 and the KU Leuven Methusalem SOUL grant METH/24/012. S. Mathis acknowledges support from the PLATO CNES grant at CEA/DAp, from the Programme National de Planétologie (PNP-CNRS/INSU) and from the European Research Council through HORIZON ERC SyG Grant 4D-STAR 101071505.

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