In about a billion years, the sun will grow hotter, expanding its habitable zone and making Earth increasingly uninhabitable. However, a slim chance exists that a passing star might alter Earth's orbit, potentially saving it from this fate, as proposed in a recent theoretical study.
Currently, Earth sits within the sun's habitable zone, where liquid water can exist. Over time, the sun's expansion will push this zone farther away from our planet, jeopardizing the possibility of life well before the sun's eventual transformation into a red giant in 5 billion years.
Scientists simulated scenarios wherein a passing star could influence our solar system's dynamics within the next billion years. This investigation aimed to determine if such an encounter could eject Earth from its orbit, possibly leading to a free-floating existence as a "rogue" planet.
The simulations, totaling 12,000, involved different-sized stars approaching our solar system at varying distances, even as close as 1 astronomical unit (AU), equivalent to the Earth-sun distance. Some outcomes showed the passing star nudging Earth into a colder orbit, while others resulted in Earth being flung into the distant Oort cloud.
Intriguingly, a few simulations indicated that the passing star could gravitationally tug Earth along, capturing it into a new orbit around the foreign star. This scenario could theoretically offer conditions suitable for liquid water and potential habitability.
Despite these possibilities, the chance of such a stellar rescue is incredibly slim, estimated at approximately 1 in 35,000. The odds are akin to drawing the ace of spades from two separate decks of cards and rolling a combined 10 with two dice—certainly not favorable.
Rather than relying on such a fortuitous event, the study's lead astronomer recommended exploring alternative solutions, such as human intervention to modify Earth's orbit or devise methods to mitigate the sun's escalating energy.
Some simulations portrayed dire outcomes, including planetary collisions within our solar system. For instance, Mercury frequently met a fiery demise in these scenarios.
Nonetheless, the majority of simulations, more than 90%, indicated no significant changes in the orbits of the planets in our solar system due to the passing star. Overall, the impact on our neighborhood appeared minimal, either for better or worse.
While the possibility of a passing star altering Earth's fate remains a remote and improbable event, it prompts reflection on humanity's role in safeguarding our planet's future rather than relying on cosmic chance for salvation.