Can something in space
cause animals to be born with two heads?
Why were the most fearsome warriors
our planet has ever known
stopped by a flaming light in the sky?
How did Columbus use secret knowledge of the heavens
to cheat death in the New World.
Our ancestors saw a universe filled with bad omens.
But what were they really seeing?
And how did fear of these objects in the sky
change history?
Ancient mysteries,
shrouded in the shadows of time...
Now, can they finally be solved
by looking to the heavens?
The truth is up there,
hidden among the stars
in a place we call...
For our ancestors,
the skies were filled with equal parts wonder...
And terror.
Bad omens from above changed human history...
again and again.
Four centuries before the birth of Jesus,
it is a time of war...
Athens versus Sparta.
And this time it's for keeps.
Control of the ancient world hangs in the balance.
Thousands of brave warriors,
hundreds of ships at sea...
all poised for action,
waiting for the command from their leaders
to unleash hell on Earth.
And then...
An omen...
a strange light in the sky...
a fiery object said to be visible
for 75 days...
as both sides nervously watch and wait.
It's an omen.
But what does it mean, and what is the object?
The Spartans devise a strategy.
They send an envoy to the Greeks,
saying that with such a bad omen overhead,
battle would have to wait.
As days stretch into weeks,
the Greeks grow confident no attack is coming.
So that is when the Spartans strike...
A sneak attack...
decimating the Greeks
and marking the beginning of the end
for the nearly 30-year-long Peloponnesian War.
The final toll is staggering...
More than 3,000 Greek men captured and killed on the spot.
It couldn't be any clearer.
To the Greeks, the defeat was definitive proof
the Greek Gods had sent the sky object as a bad omen.
If you're in the middle of a war
and you see an omen in the skies,
that's gonna mean something bad.
It's something to be concerned about.
But what was the object in the sky
that brought an end to nearly 30 years of war?
One account of the object describes,
"A fiery body of vast size,
"as if it had been a flaming cloud,
"not resting in one place, but moving along
with intricate and irregular motions."
Could the ancient Greeks have been describing a meteor?
Also known as shooting stars,
meteors make a fiery display as they streak across the sky.
But since they're actually small rocks and bits of dust
burning up as they fall through the atmosphere,
meteors don't last very long.
They're visible for a matter of seconds,
not days or months, as the Greeks described.
Asteroids take longer to pass through the sky,
but because they're dark,
almost none of them are visible to the naked eye.
What the ancient Greeks could have seen, however,
was a comet.
Mythmakers fear comets, because they linger in the sky
for weeks, even months at a time.
The idea of seeing a comet for 75 days, I could buy that.
On average, only one bright comet is visible
to the naked eye each decade,
meaning the appearance of one in the sky
would've been a rare and remarkable event
to the ancients.
Comets are made of materials
that we find readily here on Earth.
They're largely made up of dry ice,
frozen carbon dioxide like we exhale,
as well as water, a little bit of organic material,
ammonia, not too different than what's in cleaning materials,
and even silicates like in sand from the beach.
When you mix all of these ingredients together,
you have the recipe for a comet.
When the ancient Greeks
described a flaming cloud in the sky,
is this what they were seeing...
A comet, changing its position in the sky
almost nightly,
faster than anything they had ever seen?
And what gives these icy objects the fiery appearance
that spooked the ancients?
As comets streak
into the inner part of the solar system,
they slowly heat up from the Sun's heat.
As they heat up, they grow an amazing tail
that doesn't streak out behind them,
the way a lot of people think,
but rather it's pushed by the Sun's radiation.
How we're able to see that tail
depends on where we are relative to the Sun
and the comet.
And sometimes that tail's pushed out
such that as the comet flies away from the Sun,
it flies into its own tail.
Comets may hold the answer
to one of the most fundamental questions
about our planet.
On Earth, where there is water,
there is life.
But just where did that water come from?
Many have proposed the water in Earth's oceans
was delivered by comets
crashing into the planet.
Others believe the water hitched a ride
inside rocky asteroids.
Which theory is correct?
Enter Rosetta...
A mission designed to survey then land a space probe
on a comet.
Rosetta and its lander, called Philae,
tracked down a comet known as 67P
after a ten-year journey through space.
So how do you get to a comet?
Loop around our solar system multiple times,
including a daring low-altitude skim
less than 200 miles above the surface of Mars.
Then jam on the brakes.
After establishing a stable orbit of the comet,
the Philae lander was deployed,
and the world watched and waited.
The gravity on a comet is so little
that the pull on that spacecraft was no different
than the weight of a piece of paper on your hand.
The lander had to be equipped with harpoons
that would help attach it to the surface of the comet.
When those didn't deploy,
the lander actually bounced,
making it not just a day for the first comet landing,
but also the second.
Unfortunately, when Philae finally came to est,
it was partially in the shade of a cliff.
That meant that the solar panels were only receiving
about an hour and a half of sunlight,
instead of the six hours that we were anticipating
that they would.
However, the Rosetta team deployed all
of its instruments at once,
trying to get as much data as they possibly could
before the lander ran out of batteries.
Despite the bad luck,
the Rosetta mission was able to make a significant discovery.
It appears unlikely a comet like this one
brought water to our planet.
Its vapor has a different chemical mix
than we see on Earth.
That leaves asteroids as the most likely source
of our water...
an important finding that could tilt
decades of debate.
Even if comets didn't bring water here,
they do carry with them a set of beliefs,
superstitions, and omens
unlike anything else in the night sky.
Were the ancients right
that there's one comet in the solar system
with the power to cause the birth of two-headed animals?
And could that same comet end all life on Earth?
Dy, France,
the year 1066...
a grand army prepares for an invasion
that could change the course of history.
They are Norman French soldiers,
descendents of Vikings and warriors,
and they are led by a man
who will become known as William the Conqueror.
William's army is on the move,
inspired by an omen in the night sky.
And what a sight it is.
Where once there was only the normal stars and planets,
now on view is an object four time larger in the sky
than Venus
and a quarter of the brightness of a full moon.
The Normans take the comet's appearance
and the disruption in the heavens
as an omen that God is angry at their enemy...
The English king Harold.
Comets have been associated with the death of kings,
because comets linger in the heavens.
Meteors, they just come and go,
but comets linger in the heavens,
signaling that the gods are angry at the king
and the king must die.
October 14, 1066...
The Normans have crossed the English Channel
and engaged King Harold and his forces
at the Battle of Hastings.
It's time to fight and, for thousands of men,
time to die.
When the battle finally ends,
6,000 men are dead, more English than Norman.
That includes King Harold,
whose advisors had warned him the object was a bad omen.
And it works. The Normans won.
The Anglo-Saxons lost.
The history of the English-speaking world
changed forever.
The battle and the omen
live on in a famous work of art.
The Bayeux Tapestry is an incredible work of art.
It's 230 feet long,
and it tells the whole story of the invasion.
It shows them crossing the English Channel.
It shows them in battle.
It shows the Anglo-Saxon shield wall.
It even shows the Anglo-Saxon king dying
with an arrow in his eye.
And there, hovering over it all,
is the omen that set it all in motion...
Not just any comet,
it's Halley's Comet.
Halley's Comet has been recorded
by Chinese astronomers and on ancient stone tablets,
dating back thousands of years.
The comet swings by the Sun
once every 75 or 76 years,
making it the only comet visible to the naked eye
that you can see twice in a lifetime.
It seems nearly every time Halley's Comet swings by Earth,
it shakes up our history.
The ancient Swiss thought of Halley's Comet
as such a bad omen,
they blamed it for everything from earthquakes
to the birth of two-headed animals.
Following its appearance in 1456,
it is said the Pope excommunicated the comet,
thinking it was a bad omen for Christian soldiers
battling the Ottoman Empire.
But is fear of Halley's Comet just superstition,
or could it really cause earthly Armageddon?
Imagine...
November 27, 2061...
As amateur astronomers gather for a look at Halley's Comet,
stunning news is confirmed.
There has been a change in Halley's orbit,
and it's headed straight for Earth.
If a giant comet were to crash into the Earth,
it would really ruin your day.
First of all, there would be a blinding flash of heat
traveling at the speed of light,
infrared radiation, heat radiation coming out.
Then a few seconds later, the shockwave.
The shockwave traveling near the speed of sound,
pulverizing everything in its wake.
And then after that, perhaps we would have a tsunami
coming at you.
Remember that Halley's Comet is about 20 miles across,
about the size of Manhattan,
but the object which destroyed the dinosaurs
65 million years ago was only 6 miles across.
And so, if we had Halley's Comet
hit the planet Earth,
it would be not just a city buster,
it would be a planet buster.
Even today we have the technology
to track and photograph Halley's Comet
at every point in its orbit.
In the future, there is time to develop a plan
to save humanity.
If we have a comet and we've been following its orbit,
for many, many years and we know it very accurately
and we can predict the collision with Earth
decades ahead of time,
then we might be able to do something
about that comet before it hits the Earth.
You can send a spacecraft up there and tug it a little bit
so that a bit at a time we pull it away
in such a way that it doesn't hit the Earth.
The truly dangerous comets
are the ones we've never seen before...
Objects with orbits so long
that they come in once every thousand
or ten thousand years.
For a comet coming in for the first time
in recorded history,
there's essentially nothing we can do
with today's technology.
We have a few months' warning, maybe one year at maximum.
We don't know the trajectory very well.
We can't send up the spacecraft.
So I'm sorry to say that if there's a giant comet
with Earth's name written on it
heading toward us for the first time,
it's good-bye, cruel world.
I'm sorry.
A really bad omen that actually comes to pass.
If a new comet is approaching Earth for the first time
in recorded history,
it's definitely coming in fast.
Visualizing the motion of a comet in its orbit
is kind of like visualizing the motion of a ball
being tossed into the air.
It starts out moving fairly quickly,
slows at the apex,
and accelerates back towards the ground.
This is, in fact, a partial orbit.
Let's look at one full orbit.
So, as a comet moves away from the Sun,
it's moving fairly quickly
until, under the Sun's gravitational influence,
it slows, reaching the apex,
a point we call the aphelion.
From that point on,
it accelerates back towards the Sun, coming...
back to its original position.
With our newfound understanding of the dangers that lurk
in the solar system,
we do have to be aware that some of these bad omens
indeed do turn out to have terrible effects
on humans on Earth.
While our ancestors feared comets,
they were even more frightened of another bad omen in the sky...
One that arrives with a sudden shadow and the terror
of daytime turned into a potentially endless night.
In the tenth century,
a group of Vikings are on top of the world.
They've set sail from what we would now call Norway
and are bound for the Shetland Islands
off the coast of modern-day Scotland.
And while they may be ready
for anything the North Sea can throw at them,
nothing can prepare them for what is happening
in the northern sky.
One minute, bright sunlight.
Then suddenly, a shadow starts to blot out the Sun.
What's going on?
Norse mythology tells of twin wolves
who track the Sun and moon.
When they catch them and devour them,
that will signal the beginning of Ragnarok...
The end of all things.
For a Viking, the question he must face is simple
yet chilling...
is this it?
With the midday sun getting darker by the second,
is this the end of the world?
This is the bad omen
that is a solar eclipse.
Historically, in China,
people would go outside and bang pots,
because they perceived the solar eclipse
as a bad omen of a dragon consuming the Sun,
and by banging the pots, they were scaring away the dragon.
In the case of a total solar eclipse,
it actually gets reasonably dark.
It can last several minutes.
You don't know that the Sun's gonna come back.
You could go wild
with uncertainty about your future, and, indeed,
ancient cultures would sometimes react
in very, very negative ways to an eclipse.
There would be mass murders.
All sorts of things could happen.
Mayhem would break loose.
In 585 BC,
a six-year conflict
near present-day Turkey
is thrown into turmoil when the day becomes night.
There's some evidence that on May 28, 585,
a battle between the Lydians and the Medes
was stopped because of a solar eclipse.
They were into the sixth year battling each other,
and near sunset, a solar eclipse occurred.
The battlefield goes quiet,
as all involved look to the heavens.
And they said, "The gods are giving us a sign.
We shouldn't be fighting."
So they made a truce and even offered
their own sons and daughters to the other side for marriage.
That was a good thing,
even though it was initially thought of as a bad omen.
So what's really going on during a solar eclipse?
A solar eclipse occurs
when the moon goes exactly,
or nearly exactly, between Earth and the Sun.
So the moon's disc
blocks part or all of the Sun's disc.
And the Sun is so important in our lives that the idea
of something going in front of it and blotting it out
would be just a remarkable event.
So you can imagine this would create fear,
or perhaps it would be interpreted
as a sign of something terrible to happen.
But none of this would matter.
Eclipses on Earth wouldn't be possible
without an amazing coincidence.
One that isn't duplicated anywhere else
in our solar system.
The sun and the moon just happen to be
the same apparent size in our sky.
That's because, while the moon's diameter
is about 400 times smaller than the Sun's,
the moon itself is 400 times closer to us.
It's a celestial accident that the disc of the moon
just covers the disc of the Sun.
And so these eclipses have fascinated astronomers
for thousands of years.
The perfect fit of Earth's moon
makes eclipses possible.
But will that always be the case?
Year by year, inch by inch,
the moon is moving further away from Earth.
Someday in the distant future,
the moon will no longer completely block the Sun.
The moon continues to go away from the Earth,
appearing smaller and smaller in the sky.
That means that in about half a billion years,
total solar eclipses will no longer be possible.
So we've lived in a special time
where we can enjoy the beauty
of what the ancients thought were bad omens,
and we now understand them
and can appreciate them for how beautiful and rare
they really are.
Our ancestors also saw lunar eclipses as a bad omen.
A lunar eclipse foretold famine and disease,
according to the Chinese.
In Japan, lunar eclipses were associated with earthquakes
and meant disaster was on the way.
But does science support this superstition?
If the sky turns dark, will the ground roll and roar?
The ancients looked warily on the night sky,
where sudden changes might foretell impending doom.
The disappearance of the moon in a total lunar eclipse
struck fear into our ancestors.
But did it also, as some believed,
cause earthquakes.
Some people in Japan, in particular,
have thought that total lunar eclipses cause
bigger or more frequent earthquakes.
So lunar eclipses were bad omens for that reason.
December 21, 2010...
For only the second time in the last two millennia,
a lunar eclipse takes place
on the day of the winter solstice.
In Japan, a massive 7.4 earthquake
triggers tsunami warnings along the coast.
30 years prior, a 7.7 quake
killed 25,000 people in Iran,
just a few hours before the start
of a total lunar eclipse.
Could it be that when the Sun and moon
are in perfect alignment,
their combined gravity has enough influence on the Earth
to trigger killer quakes?
The truth is that if you look at long-term statistics,
you don't see this.
And physically, we can't think of a reason why
a total lunar eclipse or a partial lunar eclipse
would lead to more earthquakes.
It's bunk, basically.
A lunar eclipse happens
when the Earth's shadow covers the moon.
If the disappearance of the moon
wasn't frightening enough to ancient eyes,
during some eclipses,
the moon actually changes color.
When our moon passes through Earth's shadow,
it can turn blood red.
To the ancients, that was a bad omen.
From the moon's perspective, during a total lunar eclipse,
the moon is receiving the Sunlight
of all the Sunrises and sunsets on Earth.
And that light is predominantly orange or red,
having traveled through all of that air
and dust and whatnot in the atmosphere.
As frightening as they were,
some sky watchers eventually realized
that eclipses were predictable.
Omens in the sky are something that you can make use of.
If you have superior knowledge of eclipses, you can use it.
One person to take advantage of that knowledge,
the famed explorer Christopher Columbus.
In 1502, Columbus and his crew
were stranded in Jamaica and running out of food.
And the natives, basically, were no longer thinking
that there is something special and God-like,
you know? They were losing their oomph.
Columbus is said to have access to a perpetual almanac
that contained more than 300 pages
of sky tables, charts,
and eclipse forecasts.
Columbus happened to know that there was a total lunar eclipse
coming up the next night,
and he told the natives that if they don't continue
to provide food, the moon will go away.
Sure enough, the next night, a lunar eclipse did occur,
as predicted by Columbus.
And so this raised him,
his stature, in their eyes,
and the next day they started providing goods and services
once again.
It's been said that all warfare is based on deception.
And some of the world's greatest military leaders
have used deceptions based on lunar eclipses.
The famed T.E. Lawrence,
better known as "Lawrence of Arabia,"
is said to have timed his assault on Aqaba
to a lunar eclipse.
Muslims Turks holding the town
were distracted on the night of the eclipse.
As was their tradition, they were busy making noises,
firing rifles and banging pots
in an effort to rescue the moon.
Using his knowledge of science and superstition,
Lawrence and his Arab fighters were victorious,
taking the town without losing a single man.
September 20, 331 B.C.
Alexander the Great is outnumbered
and headed for defeat
at the hands of Emperor Darius of Persia.
Alexander the Great was very smart.
There's a lunar eclipse.
You know it's an omen of something.
You don't want your own army to become disheartened,
so he used it as a propaganda coup.
As the moon glows blood red,
Alexander's secret weapon goes to work
and the great leader launches a desperate plan
to save himself, his men
and his empire.
In the ancient world, bad omens from the heavens
were exploited to change history.
On a battlefield in Mesopotamia,
Alexander the Great turns a lunar eclipse
into a weapon of fear.
Alexander the Great spread word via his astrologers
that the lunar eclipse meant that the Persians
were going to lose.
His men take heart,
they make sure they spread this message
to the enemy army...
They lose heart. It's a fantastic coup
in terms of undermining the enemy morale.
Of course it helps them win the battle.
The bad omen, paired with
Alexander's tactical superiority
is a devastating blow against the Persians
as Alexander romps to victory
and into history.
Nearly 300 years later,
another omen would play a part
in history's most notorious betrayal
and assassination.
From a hilltop in the mountains north of Rome,
observers gather and watch with trepidation
as an unblinking red dot rises in the night sky.
The date, March 15, 44 B.C.
The Ides of March.
Julius Caesar is dead.
And now, it appears Mars is angry.
The Roman had whole colleges of priests
who were responsible for interpreting the omens.
Omens in the sky, omens from the birds,
omens everywhere. They were the guys you went to.
What does it mean?
On the night of Caesar's death,
it was said that Mars was especially bright and red,
as though marking a triumph over the emperor.
More than 2,000 years later,
we know Mars isn't red because it's angry.
Mars is red, literally,
because it is rusty.
There's leftover water on the surface of Mars
and below the surface.
Leftover from when Mars formed.
And it rusts or oxidizes
the iron in the surface.
But why would Mars be brighter on certain nights,
giving it extra power as an omen?
The distance between Earth and Mars varies
as the two planets orbit the Sun.
Earth circles the Sun
once every 365 days.
Mars takes 687 days,
meaning that at some times during their orbits,
Earth is getting closer and closer to Mars.
Finally, the planets reach the phase
astronomers call opposition.
That's when Mars and the Sun are on opposite sides of the Earth.
It is during opposition that Mars is closest to Earth
and shines its brightest.
When the Sun is directly between Mars and Earth,
the planets are farthest away from each other,
about seven times farther
than they were during opposition.
Ancient observers often saw omens
in the bright celestial objects
we know today as planets.
But could a planet be responsible for
an ancient mystery
buried in the jungles
of Mexico's Yucatan Peninsula?
For years, archaeologists studying the Mayan ruins
at Chichen Itza
wondered why twin staircases on one of the buildings
are out of alignment.
Could it be somehow connected to the astronomer priests
who wielded tremendous power in Mayan culture?
By offsetting the stairs,
what message were they trying to send across the centuries?
We do know this...
the Mayans called Venus "the great star."
Mayan leaders would always account for
the position of Venus
in their calculations for battles and raids.
When Venus is close to the horizon,
it can shimmer, it can change colors.
Venus has been reported as a UFO
more times than any other object in the universe.
You can imagine, to the ancients, when it was doing
those weird things, those twinkling and changing colors,
that could be seen as a bad omen.
The Mayans would actually block their chimneys,
so what they feared as the evil light from Venus
couldn't get into their homes.
If you look at Venus, orbit after orbit,
month after month, you'll notice that
it traces out a pattern in the sky.
These different patterns are actually reflected
in Mayan architecture.
And so, the mysterious message
is revealed.
The misalignment of the grand staircase
at El Caracol,
an ancient Mayan observatory,
actually matches perfectly
with Venus's most northern appearance in the sky.
Bright lights in the sky always attracted the attention
of our ancient ancestors.
And while some were merely ominous,
others crackled with the threat
of imminent attack.
Darkness reigns.
Polar bears are common here.
So, too, are elk
and other dangerous creatures
that serve as both predator and prey
for the hearty few who make this land their home.
It is dark and scary
and potentially deadly.
Suddenly, a man out hunting sees it,
a threat known to his people since ancient times.
So he does what comes naturally,
what generations of native Alaskans have done before him.
He draws his weapon
and prepares to defend himself
from the swirling electrical madness
he sees in the skies.
Blazing lights.
A mysterious and ever-changing symphony of color.
Today, we know this phenomenon as the aurora borealis,
the Northern Lights.
And for many cultures, like the Eskimos
living near Barrow, Alaska,
the aurora is a bad omen.
Auroras, the northern or southern lights,
have often been seen as bad omens because
there are these ghostly lights in the sky
and they're flickering and they're of unknown origin
to the people watching them.
Are the gods angry or something?
So what causes this sparkling show in the sky?
Aurorae are fascinating examples
of the interaction between
the Sun and us here on Earth.
The sun has what we call space weather.
These are solar flares or other phenomena associated with
the Sun's magnetic activity
that shower our planet with not only high energy radiation
but also energetic particles.
Earth has a magnetic field.
Now, if that magnetic field was in isolation,
it would look sort of like a cored apple.
But it's not in isolation.
The solar wind charged particles streaming out of the Sun
impinges upon Earth,
flattening the nearside and extending the farside
of that field.
It also has holes at
the north and the south
called polar cusps.
Solar wind can flow into the polar cusps,
creating the aurora borealis
and the aurora australis.
As they excite the gases in our atmosphere,
depending upon the gases that get excited,
you get different colors.
These different gases are exactly what are used to make
the neon signs that we see down at the deli.
When you see that green palm tree or that red open sign,
those are different gases being energized
and it's the light escaping
as the electrons change energy levels
that we perceive as these different colors.
The spectacular light show an aurora provides
isn't the only way to experience one.
As it turns out, you can actually hear an aurora too.
There have always been stories of people hearing sounds
associated with the aurora.
Popping and whistling noises.
But it was unclear if these were just stories
or real, until recently
when scientists were finally able to record
that, under very certain circumstances,
you can hear whistling and popping noises
associated with the Sun's energy interacting with
our own Earth's atmosphere.
What causes the sound is still a bit of a mystery.
Researchers think the same solar energy waves
that generate the spectacular lights in the sky
are also responsible for the sounds closer to the ground.
The phenomenon of auroras is an ancient mystery
that stretches across the cosmos.
Jupiter has amazing aurorae that we see on a regular basis.
Saturn has aurorae.
And even Venus.
Omens, portents, and signs
are how ancient people made sense of their universe.
Today, astronomers are making remarkable discoveries
that help explain the science behind
these once terrifying events.
One of the things that's really amazing about
the time that we live in, is that all of these things
that were very scary for our ancestors
we now understand through the lens of science.
Humans always want to know about the future.
Whether you're an ancient Roman, an ancient Chinese,
a person living in America in the 21st century,
we want to look for signs in nature, signs in the heavens,
that can help us understand things,
can reassure us that we know
what will happen in the future.
As we learn more about the universe,
knowledge is replacing fear.
People go north to see the aurora.
They take eclipse cruises.
Yesterday's bad omens are today's tourist attractions.
This, then, is humanity at the dawn of the 21st century,
striving to understand and experience first hand
what men and women through the millennia
formerly saw as bad omens.