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  • With the vastness of the Universe,

  • everything in it seems so spread out.

  • But some objects are closer

  • than you might realize.

  • Every now and then,

  • a random interstellar asteroid

  • passes through the Oort cloud,

  • the wall of icy debris at the very edge

  • of our Solar System.

  • But what if a rogue star

  • unceremoniously rampaged

  • right through the Oort cloud?

  • How bad would it be, if it brought

  • other planets along for the ride?

  • What if I told you that a rogue star

  • has already invaded our Sun's territory?

  • A dim red dwarf, dubbed Scholz's star,

  • crossed the Oort cloud some 70,000 years ago.

  • It passed just 0.8 light-years

  • away from the Sun.

  • And then it made a turn in the opposite direction,

  • without causing much trouble.

  • Right now, another rogue star

  • is moving in our direction.

  • Gliese 710 has about 60%

  • of the mass of our Sun,

  • and it's traveling across the galaxy

  • at 52,000 km/h (32,000 mph).

  • If another star rampaged

  • through the Solar System,

  • the extent of the chaos it would cause

  • would depend on the size of that star,

  • and its trajectory.

  • When Scholz's star passed through the Oort cloud,

  • it came five times closer

  • than Proxima Centauri,

  • the closest star to our Solar System.

  • Scholz's star didn't have much effect on Earth,

  • although around the same time,

  • early humans almost got wiped out

  • by a massive volcanic eruption.

  • But that was pure coincidence, right?

  • In any case, before Scholz's star

  • turned away minding its own business,

  • it did change the orbits of about 10%

  • of comets and asteroids in the Solar System.

  • But, what if it was a bigger incoming star,

  • like Gliese 710, that's currently making its way towards us?

  • Gliese 710 isn't scheduled to make

  • its first contact with the Solar System

  • for another 1.29 million years.

  • But when it does, it could shake the Earth quite a bit.

  • At first, the rogue star would

  • make its way into the Oort cloud.

  • At this point, it wouldn't affect us directly.

  • But it would send massive chunks of space rock

  • showering the Solar System.

  • About 170 meteors, comets and asteroids

  • would hit the Earth every day.

  • That's ten times more

  • than what's bombarding our planet right now.

  • Comets and meteors might not seem like a big deal,

  • since most of them are small,

  • and they often fall in unpopulated regions. But...

  • Back in 1908, in Siberia,

  • it only took one asteroid to obliterate 80,000 trees,

  • and blow out windows 60 km (37 mi) away.

  • If the same asteroid were to hit New York,

  • the entire city would be in the impact zone.

  • And that's if just a single star smaller than the Sun

  • slightly made it just inside our Solar System.

  • If a star larger than our Sun

  • entered the Oort cloud,

  • it would disrupt the orbital cycle

  • for every planet it passed.

  • Since there are such large distances within the Solar System,

  • this disruption would happen

  • over the span of millions of years.

  • It would be an almost slow-motion

  • chaos of debris waves.

  • It might even set some planets on a collision course.

  • And that's not the worst it could get.

  • If the rogue star had other planets and moons following it,

  • our Solar System would turn into a galactic soup,

  • with stars and planets

  • being pulled out of their orbits.

  • Massive collisions would create a rippling effect,

  • disrupting planetary orbits even more.

  • Eventually, the Earth would be

  • knocked out of its orbit too,

  • if it wasn't already destroyed by meteor storms

  • and the remnants of other planets.

  • Not to sound too dramatic, but there are estimates that

  • 40,000 stars have entered the Oort cloud,

  • at some point in the history of the Solar System. But...

  • They all came here on "just visiting" trips.

  • Chances that any of those rogue stars

  • will ever make it past the Oort cloud

  • are close to zero.

  • Let's just hope that we'll never have to deal

  • with anything like a black hole

  • coming too close to the Solar System.

  • But that's a story for another WHAT IF.

With the vastness of the Universe,

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