Surviving Planet Challenges Solar System Predictions

All stars eventually exhaust their fuel and transition through various phases. The sun is no exception, expected to evolve into a red giant in a few billion years. During this phase, the sun will expand, potentially engulfing nearby planets like Mercury and Venus. Despite extensive research, the fate of Earth and our solar system during this transformation remains uncertain.

Astronomers have recently discovered a giant planet that survived the end of its sun, offering insights into the process. Ryan J. MacDonald from the University of St Andrews explained that surviving planets initially move further from their dying star, owing to the reduced mass of the resultant white dwarf. However, the giant planet WD 1856b migrated closer to its white dwarf host due to the gravitational pull of nearby red dwarf stars.

In 2020, astronomers found a giant planet orbiting a dead star, or white dwarf, sparking curiosity about its survival through the red giant phase. Utilizing NASA’s James Webb Space Telescope, scientists examined the planet’s atmosphere, identifying methane and aerosols. This marks the first successful characterization of a planet’s atmosphere around a dead star, revealing that planetary atmospheres can persist despite stellar demise. The findings broaden understanding of post-stellar life and planet habitability.

Researchers discovered that WD 1856b initially maintained a safe distance from its star, migrating inward billions of years after the star’s death. Christopher O’Connor of Northwestern University highlighted the implications for our solar system, stating, “In roughly five billion years, we expect the sun to die, and this study shows planets might survive and potentially be habitable even after their star’s life cycle has ended.”

WD 1856b, a gas giant with Jupiter’s dimensions, resides around 80 light-years away. It orbits an Earth-sized star remnant, completing a revolution every 1.4 days. Despite the dramatic shift to the red giant phase, this planet endured. O’Connor proposed two explanations: it either survived engulfment by its star or migrated due to gravitational interactions with other celestial bodies.

The planet’s higher-than-predicted temperature, even accounting for the white dwarf’s heat, led researchers to surmise that its journey inward happened 5.5 billion years post-star collapse. This suggests WD 1856b safely distanced itself during the star’s destructive phase. MacDonald noted that giant planets in our solar system might also migrate closer to a white dwarf over time, potentially accelerated by gravitational interactions or interstellar influences.

This study serves as a prospective preview of our solar system’s future. By examining this planetary system, scientists gain a “time machine” perspective on the possible trajectories of planets orbiting remnants of stars like our sun. MacDonald concluded that stellar death does not signify the end; some planets thrive beyond their star’s demise, experiencing dynamic futures.

Reference: MacDonald, R.J., O’Connor, C.E., Boehm, V.A. et al. Aerosols and hydrocarbons in the atmosphere of a white dwarf planet. Nature 655, 76–80 (2026).