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
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