Experts Identify a 'Death Star' in Our Future

Imagine this: Our solar system is busy minding its own business, whittling its days away in its predictable orbits and rotations, when suddenly a rogue star comes crashing by, knocking comets and asteroids into erratic paths straight for Earth. A new study says that such a scenario is entirely possible, but it's nothing to fret over.

The idea of "Nemesis" or "Death Star" scenarios is nothing new. Astronomers have long known that rogue stars drift through any number of galaxies, untethered by a solar system of their own and looking for trouble.

Stars are incredibly massive and dense, with the Sun - an average yellow star - boasting about 333,000 times the mass of Earth. Red dwarfs, the most common of small stars, are but a 13th of that mass, which is still more than enough to have a destructive gravitational influence on the Oort Cloud - a spherical field of comets and other icy planetesimals that surround our Sun.

That means that for countless comets and asteroids to be thrown erratically hurtling through our solar system, a Death Star doesn't even need to get "hands on" with its destructive potential. A 'drive by,' so to speak, would be more than enough.

And that's exactly what Coryn Bailer-Jones, an astronomer at the Max Planck Institute for Astronomy in Germany, discovered in an analysis of more than 50,000 stars throughout the Milky Way Galaxy. He was looking for close encounters that could lead to a Nemesis scenario, and identified a stunning 42 stars that could conceivably come within two parsecs (6.5 light-years) of our own Sun. (Scroll to read on...)

Of that grouping, the red dwarf HIP 85605 (currently 16 light-years away) appeared most likely to get dangerously close. Bailer-Jones found that the star has a 90 percent probability of running a drive-by starting between 240,000 and 470,000 years from now. Yikes!

Don't Fret For Mankind

But, while that may sound frightening, our fear is for humanity several hundred-thousand years from now. Even our great-great-great grandkids will long be dust, so who is to say that humanity won't be long gone as well?

In a follow-up with NBC news, Bailer-Jones said that we as a species have far more immediate concerns.

"Of course, given a long enough time scale, then it's inevitable that something large will be on a collision course with the Earth, just as it's highly likely that a supervolcano will go off within the next few million years," he said. "These are real, but very long-term risks, and not worth worrying about now given that humanity faces equally significant risks on much shorter timescales. If people want to try to avoid doom, they should be looking to avoid human-generated catastrophes such as international aggression, environmental destruction, and antibiotic resistance."

The researcher added that it's probably more likely our planet will be struck by a near-Earth asteroid long before a dangerously large Nemesis scenario comet finds itself threatening Earthling life.

Life From Destruction

So why was Bailer-Jones even looking for these frightening events in the first place? Understanding their probability and how they might occur won't just tell us about the future of our solar system, but about its past as well. (Scroll to read on...)

A bombardment of icy comets has long been suspected to be one way in which water was delivered to Earth during the adolescent years of our blue planet.

Back in 2011, NASA's Spitzer Space Telescope detected signs that a heavy bombardment of icy planetesimal material is still occurring in the nearby system Eta Corvi. As that solar system is still young, researchers theorized that it would not be a stretch to assume the same happened within our own system in the past.

That same year, an analysis of water properties from the comet 103P/Hartley 2 was found to match the composition of Earth's waters, implying that comets brought water to a cooling Earth.

However, by the end of 2014, the European Space Agency's Rosetta project also revealed that water vapor from comet 67P/Churyumov-Gerasimenko does not match Earth's or Hartley 2's. Experts are fairly ceartain that 67P came from the Kuiper Belt - an inner field of comets in our solar system. This discovery cast the comet water origin theory into doubt, but supporters say there is still hope: water signatures among Oort comets may not be so different. Sampling these far-flung comets, however, remains impossible.(Scroll to read on...)

Keeping it Cool

However, early comets - Death Star flung or otherwise - may have had another use for a young Earth. A new water origin theory that started to gain ground back in October suggests that the young Earth was far too hot to have kept whatever comet delivered water it received from early impacts.

However, these impacts may have helped quickly cool the plant, preparing it to receive a heavy "rain" of water-laden meteorites just large enough to pierce Earth's fledgling atmosphere 14 million years after the birth of our solar system.

A study published inthe journal Science at the time revealed that water traces from the 14-million-year-old asteroid 4-Vesta matches Earth's ocean signature to a T.

And many experts will admit that this does make the most sense. If Earth was too hot for water in its youngest years, the impacts of asteroids and comets could have helped cool it in a manner similar to beating a fire, but the resulting blasts would have likely thrown new water particles right back into space.

"Surface water as it exists on our planet today, must have come much, much later - hundreds of millions of years later," geologist Horst Marschall concluded in a statement.

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