In a billion years the Earth will be too hot to handle. There is a (very) small chance that a passing star will save us by returning our planet to the habitable zone. In about a billion years, the Sun will become much larger, brighter, and hotter, possibly rendering Earth uninhabitable. But a chance collision with a passing star could save our planet by sending it into a cooler orbit or helping it escape the solar system altogether, a new theoretical study suggests. (But the probability of this is extremely low.)

Today, Earth is in the Sun’s region, a ring-shaped region within which planets may contain liquid water. But over the next billion years, the situation on our planet will worsen as the Sun grows larger and pushes this region away from the Earth. This means that liquid water, and therefore life, could be history long before the Sun becomes a red giant and completely engulfs the Earth in 5 billion years.

But what if Earth was thrown out of orbit and became a free-floating rogue planet? To investigate this possibility, a team of astronomers modeled how our solar system would behave if a star hurtled past it in the next billion years; They knew that this event could knock planets out of orbit. Their research has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society and is available in the arXiv preprint database.

Similar star flights have occurred in the past.

“Now the closest approach of any star is about 10,000 a. [астрономічних одиниць] (and this happened several million years ago),” study lead author Sean Raymond, an astronomer at the University of Bordeaux in France, told Live Science via email. “This is 10,000 times the distance from the Earth to the Sun But just to see what would happen, the team calculated the motions of the planets when stars of different sizes approached from different distances, even as close as 1 in.

The researchers ran 12,000 simulations. In some, the passage of the star pushed the Earth into a farther, colder orbit. In other cases, our planet (along with some or all of the other planets) landed in the Oort cloud, a spherical shell of icy objects believed to be at the far end of the solar system.

Even more intriguing is that in various simulations, a wandering star manages to gravitationally pull the Earth into its wake, trapping our planet in its free-spinning orbit through space. In this case, the Earth “could, in principle, settle into an orbit that receives enough energy from our new star for liquid water,” according to Raymond.

Still, it’s better not to put money on the star reliever. The researchers found that the combination of all these possibilities represents only a 1 in 35,000 chance of life continuing on Earth after the star has passed. As Raymond notes on his PlanetPlanet blog, this is about the same probability as “drawing an ace of spades at random from two separate decks of cards and rolling a 10 on two dice at the same time.” Not the best of chances.”

Rather than hoping that a star would save the Earth from imminent disaster, Raymond suggested “finding a solution ourselves by changing the Earth’s orbit or blocking some of the energy from the Sun.”

Some other simulations produced even worse outcomes for our solar system, with planets, including ours, colliding with each other or the sun. For example, Mercury often met a fiery end. But even these outcomes are unlikely. More than 90% of the simulations showed no change in the orbits of the planets in the Solar System. In general, the outgoing star will have little impact, for better or worse, on our region. Source