NARRATOR: Of the billions
of stars twinkling overhead,
one may be a scourge to
life on Earth, an evil twin
to the sun named Nemesis.
Some scientists
suspect that Nemesis
is a dark, still undiscovered
star orbiting our sun.
And every 26 million years,
it triggers a disaster.
We know that the
solar system is
surrounded by this
enormous cloud of comets.
And so these successive
passages of the sun's companion
would send comets into
the inner solar system.
Some of them would hit Earth.
NARRATOR: What follows is
death on a colossal scale.
It is now widely accepted
that a rock from space
caused the end of the age of
dinosaurs 65 million years ago.
But astronomer, Richard
Muller, has proposed
a revolutionary
theory to explain
why that space rock
crashed to Earth
at that particular moment.
The Nemesis theory
postulates that
there's a star orbiting the sun
at a 26 million-year period.
That's about it.
Almost no other assumptions
need to be made.
NARRATOR: Muller believes
that as Nemesis nears the sun,
its gravitational disturbance
sends comets flying
through the solar system.
The resulting impacts
have been the source
of many major extinction
events in Earth's history.
Muller explains how
the theory came about.
RICHARD MULLER: Two
paleontologists,
when looking at
patterns of extinctions,
came across something that
seemed utterly insane.
They said that
similar extinctions
were taking place
every 26 million
years on a regular schedule.
NARRATOR: The discovery of
a 26 million-year pattern
of extinctions seemed impossible
to explain by any process
native to the Earth itself.
RICHARD MULLER: This
is the sort of thing
you dream about in science.
It means there's something
we don't understand.
It means there's a
discovery waiting.
So I set about trying to
figure out what that was.
NARRATOR: Muller made
an astonishing proposal.
The only logical cause of
these periodic extinctions
is a cosmic stalker that orbits
our sun every 26 million years,
disturbing the comets
on each approach.
In short, a Death Star
companion to our sun.
RICHARD MULLER: If this star is
discovered, it is so important.
It was a major player in the
evolution of life on Earth.
Without this, perhaps the
dinosaurs would still be here.
NARRATOR: If Muller
is right, humanity
itself could owe its existence
to the Nemesis Death Star.
After all, each mass extinction
wiped out vast numbers
of species, but each also
cleared the way for new species
to arise, including,
ultimately, humans.
RICHARD MULLER: Now why
haven't we found it yet?
Actually, there are
quite a few astronomers
who don't pay very
much attention to this
and simply assume
that if it existed,
it would have been found by now.
We believe this
thing can be found
within the next few years.
What it takes is a
survey of dim stars.
NARRATOR: Enter WISE, the
orbiting Wide-field Infrared
Survey Explorer, a powerful
new tool that just might
crack the Nemesis mystery.
The reason that WISE
is going to be so good
is because it operates
in the infrared.
It sees heat, basically.
NARRATOR: By measuring
heat instead of light,
infrared scanners can make warm
but dark objects easy to spot.
The nice thing about
looking in the infrared
at the heat of it is,
you don't care how
far away you are from the sun.
NARRATOR: Jupiter
provides an example.
The temperature on
the surface of Jupiter
measures 230 degrees
below 0 Fahrenheit.
But that's blazing
hot when contrasted
with the 450-degree below
0 temperature of space.
So even in the
absence of sunlight,
a distant Jupiter-like
planet would
glow brightly in the infrared.
The hot spots of the
race car are sort of
like warm, glowing objects out
in the cold depths of space
far from the sun.
This is a whole new way of
discovering objects, objects
too faint to be seen through
a normal optical telescope
but bright enough to be
detected in the infrared.
NARRATOR: The WISE
telescope completed
its sky survey in early 2011.
But in the search for
Nemesis, the results
are still inconclusive.
The WISE survey is going to
take a long time to analyze,
simply because there's a
huge amount of data that had
been gathered by this craft.
RICHARD MULLER: About half
of the Nemesis candidates
have not yet been studied.
But in the next few years,
we expect the theory will be
either proven right or wrong.
Until that time, it is and
should be controversial.
