Every once in a while, life on Earth
goes a little haywire whether it's because of comet impact,
volcanoes erupting all over the place, occasionally a lot of species go extinct
all at once in what is appropriately called an extinction event. In 1984
a group of scientists noticed that most of these events
both the big catastrophic ones like the one that wiped out the dinosaurs and the
smaller kinda just bummer extinctions,
happen just about once every 30 million years. The scientists didn't
propose why this pattern existed they just dump their data on the lap of the astronomy
community and basically said
"Have at it, science" Well, new research published last week by the Royal
Astronomical Society seems to support one of the more recent theories about
why extinctions happen.
Maybe they're caused by dark matter.
Okay dark matter is the type of matter that doesn't emit or absorb light or any
other kind of electromagnetic radiation and thus it is very hard to look at it
because the whole not interacting with
radiation thing, so nobody knows for sure what it's made of
but for the laws of physics as we know them to work, dark matter
has to exist. That's because some objects like galaxies exhibit the gravitational
effects have objects with much more mass than they actually have.
So physicist theorize that there had to be some other kind of matter out there
that they couldn't detect
hence dark matter. Now in 2013 a group of physicists from Harvard published
calculations suggesting that a bunch of this dark matter
might be sandwiched in the dense middle layer of the disc of our Galaxy,
and two physicists from this group proposed that this dark matter sandwich
might have everything to do with Earth's extinction events.
See, our sun takes two hundred and fifty million years to orbit the center of the
Milky Way,
But it doesn't just orbit in a flat ellipse, it bobs up and down along the way in a
wave pattern and,
as it happens, it passes through this dense Galactic disk
every 30 million years or so. According to these physicists it may be the dark
matter in that disk that alters the orbits of comets creating impacts on Earth
that cause mass extinctions and in this week's latest paper Michael Rampino, a
biologist at NYU, takes the idea one step further
he proposes that dark matter could actually accumulate
in Earth's core,
as it passes through the Galactic disk eventually these dark matter particles
would interact annihilating each other and producing lots of energy that would
heat up the Earth's core.
This, he says, could explain the sudden ramp ups in geologic activity like
massive volcanic eruptions that change Earth's environment enough that some
species simply can't survive. So the dark matter extinction hypothesis does fill
in some blanks like
why extinctions that weren't caused by comet impacts also fit the timeline
but so far it's all theoretical, while calculations work, it can be hard to tell
the difference between real causes and mere coincidence if you've gotta catch in
your chips though, it's hard to think about more impressive epitaph than
"done in by dark matter" Moving on to a slightly more recent past new research
has found that a star,
might have paid our solar system a visit. Known as Scholz's Star, it may have passed as
close as 0.8 light years from us as recently as seventy thousand years ago
when the star was first discovered in 2013 a team of astronomers at the
University of Rochester noticed something odd, it was
speeding away almost directly from our solar system tracing its path backward
they realize that the star very likely
passed right by us. Now, point eight light years is still pretty far away that's
more than seven
trillion kilometers but it's still way closer than our nearest neighbour right
now Proxima Centauri which is 4.2 light years away.
Scholz's Star is a very dim red dwarf so even when it buzzed our solar system it
wouldn't have been visible to the unaided eye from earth but according to
the calculations coming out of Rochester, it may have come close enough to pass
through the
Oort cloud; the comet field region at the end of our solar system and if it
did there's a slim chance that it could have
interacted with some comets in that cloud, potentially is slinging a few them
in the direction of the Sun
now Scholz's star was probably too small and too fast
To wreak much havoc but if it did manage to kick some comets lose they won't get
here for another few hundred thousand years.
So guess we'll have to wait and see on that one. But this discovery just like
the dark matter studies I mentioned earlier shows that our solar system is
indeed
and very busy place. Thanks for joining me for SciShow Space news, if you wanna
keep up to date on the latest space news and space stuff, you can go to
Youtube.com/SciShowSpace
and subscribe