A couple of billion years from now, the sun could have turn into much greater, brighter and warmer, likely leaving Earth uninhabitable. Nonetheless, a probability encounter with a passing star could save our planet by tossing it right into a cooler orbit or helping it break freed from the solar system entirely, a brand new theoretical study suggests. (Still, the possibilities of that taking place are extremely slim.)
Today, Earth lies inside the sun’s habitable zone, a ring-shaped region inside which planets may harbor liquid water. But our planet’s situation will worsen because the sun grows over the subsequent billion years, pushing this zone outward and away from Earth. Which means liquid water — and, due to this fact, life — could turn into history well before the sun balloons right into a red giant and swallows Earth entirely 5 billion years from now.
But what if Earth were ejected from its orbit to turn into a free-floating, “rogue” planet? To research this possibility, a team of astronomers simulated how our solar system would behave if a star swept past it sooner or later in the subsequent billion years — an event they knew could kick planets out of orbit. Their study has been accepted for publication within the journal Monthly Notices of the Royal Astronomical Society and is obtainable within the preprint database arXiv.
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Stellar flybys of this type have happened up to now.
“Currently, the closest approach of any star is about 10,000 au [astronomical units] (and happened a pair million years ago),” lead study creator Sean Raymond, an astronomer on the University of Bordeaux in France, told Live Science by email. That is 10,000 times the space from Earth to the sun. But simply to see what would occur, the team calculated planetary movements when stars of various sizes approached at various distances, at the same time as close as 1 au.
The researchers produced 12,000 simulations. In a few of them, the star’s passage pushed Earth right into a farther, colder orbit. In others, our planet (together with some or all the other planets) landed within the Oort cloud, the spherical shell of icy objects believed to sit down on the outermost fringe of the solar system.
More intriguingly, in a handful of simulations, the wandering star managed to gravitationally lure Earth away with it, capturing our planet in its free-wheeling orbit through the cosmos. In response to Raymond, Earth, on this case, “could in principle find yourself on an orbit receiving enough energy for liquid water” from our latest home star.
Still, it is best not to place your money on a stellar savior. All these possibilities together amount to simply a 1-in-35,000 probability that life on Earth will survive after the star whirs by, the researchers found. As Raymond noted in his blog PlanetPlanet, that is roughly the percentages of “randomly pulling the ace of spades from two separate decks of cards while also rolling a combined 10 with two dice. Not the most effective odds.”
Fairly than hoping for a star to avoid wasting Earth from its inevitable doom, Raymond suggested “coming up with an answer ourselves, either by modifying Earth’s orbit or blocking a fraction of the Sun’s incoming energy.”
A few of the other simulations had even worse results for our solar system, with planets, including our own, colliding with each other or with the sun. For instance, Mercury continuously met a fiery end.
Yet, even these outcomes are unlikely. Greater than 90% of the simulations showed no change within the orbits of any solar system planets. On the entire, then, the passing star would have little impact on our neighborhood — for higher or for worse.