Earth could escape being swallowed by the dying Sun, scientists say

New research is rewriting the fate of Earth in the sun's final act, which was thought to expand and engulf our planet in approximately 5 billion years.

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However, a new study published in Astronomy & Astrophysics suggests our planet may avoid being swallowed by the Sun when it expands into what is known as a red giant. The study challenges previous estimates by using updated models that more accurately reflect the relationship between the Sun's gravitational pull and the mass lost during its final stage.

Lead author Mats Esseldeurs of KU Leuven explains that Earth's survival now depends less on tidal forces, which are the gravitational connection between Earth and the Sun, and more on how much mass the Sun sheds at the end of its life. If the Sun loses enough mass, Earth could drift outward just in time to avoid being engulfed.

"The largest uncertainty no longer comes from the tidal calculations, but from how much mass the future sun will lose," study lead author Mats Esseldeurs of the KU Leuven's Institute of Astronomy in Belgium said in a statement. "Observations of sun-like giant stars currently point towards Earth's survival, but we need better observations before we can be certain."

The sun's death will be a two-part process: first, tidal forces will slowly pull Earth inward, but as the star sheds half its mass, the weakened gravity will push the planet outward.

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Question #1

How do the updated models change the timeline or extent of tidal forces pulling Earth inward compared to previous estimates?

The updated models reduce the role of tidal forces in determining Earth's fate, showing tidal pull will still slowly draw Earth inward but is less decisive than previously thought. Instead, the extent and timing now depend more on how much mass the Sun loses during its red giant phase; if the Sun sheds enough mass, weakened gravity could push Earth outward in time to avoid engulfment.

Answered

Question #2

What observational methods or measurements are needed to reduce uncertainty about the Sun’s future mass loss?

Observations of mass-loss rates from sun-like giant stars are needed to reduce uncertainty about the Sun's future mass loss. The study says current observations of such stars point toward Earth surviving but are limited, so better measurements of how much mass similar stars shed near the end of their lives are required.

Answered

Question #3

How do the study’s models treat interactions with Mars and could Mars’ survival affect Earth's orbital evolution?

The study’s models treat interactions with Mars the same way as Earth, showing that both planets may survive the Sun’s two-part death: tides first pull planets inward, then mass loss from the Sun weakens its gravity and pushes planets outward. Yes; because the models find survival depends more on how much mass the Sun sheds than tidal effects, Mars surviving indicates the weakened gravity from solar mass loss can allow planets like Earth to drift outward and avoid engulfment.

Answered

Question #4

Are there predicted changes in Earth’s orbital eccentricity or inclination as it drifts outward in the models?

The primary article says as the Sun sheds about half its mass its weakened gravity will push Earth outward, so models predict Earth will drift outward during the Sun's final stage. The article does not mention any predicted changes in Earth’s orbital eccentricity or inclination.

Answered

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The new models show that Earth and Mars may survive both phases, while Mercury and Venus will be consumed. However, the study stops short of guaranteeing Earth's survival, noting that observations of mass-loss rates in similar stars remain limited.