New research suggests that Earth and Mars may not be swallowed by the Sun when it expands into a red giant.
This finding challenges previous scientific assumptions about the ultimate fate of the inner solar system. While the Sun's growth is inevitable, the survival of these planets depends on a delicate balance between solar expansion and orbital migration.
The Sun is expected to transition into a red giant in approximately five billion years [1]. During this phase, the star will expand to hundreds of times its current size [2]. Traditionally, astronomers believed this expansion would lead to the total consumption of the innermost planets.
However, updated stellar-evolution models indicate a different outcome. As the Sun ages, it loses mass through stellar winds. This loss of mass reduces the gravitational pull on the surrounding planets, causing their orbits to gradually expand outward [3].
The research indicates that this orbital migration may be sufficient to keep Earth and Mars outside the Sun's red-giant envelope [3]. Instead of being engulfed by the fiery exterior of the dying star, the planets could move far enough away to remain intact.
This shift in understanding relies on more precise calculations of how mass loss affects planetary dynamics. While the planets may avoid physical destruction by the Sun's surface, the extreme heat associated with a red giant would still fundamentally alter the environment of these worlds.
Scientists continue to refine these models to determine the exact threshold of survival. The fate of the solar system remains a subject of study as researchers weigh the competing forces of solar expansion and orbital drift [3].
“Earth and Mars may not be swallowed by the Sun when it expands into a red giant.”
This research shifts the timeline of planetary destruction from a certainty of engulfment to a possibility of survival. While it suggests the physical structures of Earth and Mars might persist, it does not imply habitability; the intense radiation and heat of a red giant would likely strip away atmospheres and boil oceans long before the Sun's surface reached the planets.
