Original subtitles

Tonight,

a fiery phenomenon terrorizing American airmen

during World War II,

Eight to 10 balls of fire

come at the Night Fighter Squadron

with serious speed and intent.

A huge red light

traveling at an estimated 200 miles an hour.

He aims his plane towards these balls of light

and prepares to engage.

And just like that, the lights all just disappear.

The men call these fiery orbs Foo Fighters.

They seem to be stalking US pilots.

But what are they?

These pilots are stressed and fatigued.

You're looking out into the darkness,

your mind is going to play tricks on you.

The witnesses were adamant, they saw what they saw,

and it defied the laws of physics.

Now, we explore the top theories

surrounding these strange encounters.

Maybe it was a secret German weapon

on a collision course with their airplane.

The idea of unidentified flying objects

was almost entirely in the realm of fiction.

This is an 80-year-old mystery, and it's still here.

What's the hidden truth

behind World War II's mysterious Foo Fighters?

November 26th, 1944,

Longvic Air Base, Dijon, France.

Allied forces are battling their way

toward the German homeland,

when American pilot, Edward Schlueter,

and his radar operator, Donald Meiers,

take off on a search and destroy mission over Germany

for the 415th Night Fighter Squadron.

The 415th

Night Fighter Squadron is the point of the spear

for a new type of nighttime war fighting

near the end of World War II.

It's six months after D-Day,

Allied forces are gaining ground,

and Germany is getting desperate.

While the tide of war is shifting

in the favor of the Allies,

there is an effort to bring the war directly to German soil,

and that leads to a growing emphasis on night fighting.

The 415th Night Fighter Squadron

are flying these stealth planes, these Bristol Beaufighters.

They're painted black, they are just armed to the teeth;

they have guns, they have cannons, they can drop bombs.

The tactic of these night fighters

was to go after things like supply trains

and military installations after dark.

That night, near Mannheim, Germany,

Schlueter and Meiers attack and destroy

a German military train.

They're headed back to Dijon,

and they see in the sky

something that they can't explain;

it's like a big red glowing light.

Schlueter reports that there's a strange red light

about 2000 feet off his starboard side.

It's like nothing they've really seen before.

In the battlefield, there are all sorts of lights

and explosions all the time,

but this is something new, something different.

After it follows their aircraft

for a pronounced period of time,

they notice that the ball of light

suddenly disappears in a long red streak.

Schlueter soon learns he's not alone.

Another aircrew on the same squadron

encounter very similar strange lights.

This has gone from being a one-off incident

to something of a developing phenomenon.

A few nights later,

the intelligence officer, Fred Ringwald,

decides to come along and see for himself.

His thinking is that perhaps

this is some sort of new German secret weapon.

On this mission, Schlueter and his crew

are on what's called a ground sweep;

they're flying very close to the ground,

following the Rhine River,

they're looking for targets of opportunity,

but they're also trying to stay below German defenses.

Ringwald suddenly spots

a strange cluster of orange lights in the distance

off the left wing of their aircraft.

This time, instead of one big glowing red light,

they see maybe about eight to 10

reddish, orange glowing objects.

Schlueter thinks they might just be stars twinkling

far, far away.

He recognizes that things can look different at night

and over great distances in the air.

But then they seem to come closer,

and he realizes this is not simple starlight.

It's eight to 10 balls of orange fire

that seem to be coming towards his aircraft

at breakneck speed.

Schlueter is like, "This is something

really bizarre."

So he gets on the radio and he says,

"Have we got any enemy aircraft in the area?"

And they say, "No. What, are you crazy?

You're the only guys up there."

And yet men in the plane,

they 100% see something coming at them.

And so, Ed Schlueter, the pilot,

he's a trained fighter pilot, he knows what he has to do.

He decides he's gonna intercept whatever this is.

He prepares to engage these strange lights

and prepares for a dogfight.

At the last moment,

these lights just disappeared off at high speed.

A few weeks later,

as Lieutenant Harry Giblin and his radar observer

crossed the Rhine into German territory,

they see two huge orange balls above them,

about 1000 feet higher in altitude.

The balls of light were moving

at an incomprehensible speed.

So whatever these things are,

they are incredibly fast

and they're incredibly maneuverable.

A few nights later,

another crew encounter two glowing balls

heading towards their plane;

and then the next night, they see exactly the same thing.

And it seems to be these balls of light

are tracking the plane.

These balls don't attack the planes,

but there's a sense of menace.

The pilots say, "Look,

we don't know what we're dealing with here,

but it's under intelligent control."

Back on the base,

the pilots named these balls of fire that they'd seen

Foo Fighters.

It's a play off of a popular comic strip

in which the main character uses the catchphrase

"Where there's Foo, there's fire."

It's a silly name,

but these airmen are deadly serious about what they've seen.

They don't think it's a figment of their imagination.

By the end of 1944,

the 415th has had more than a dozen mysterious encounters

with Foo Fighters,

and a war correspondent picks up the story.

On January 2nd, 1945,

the New York Times runs a story

about these Foo Fighter encounters;

that the Germans have thrown this new technology

into the night skies, and no one knows what it is.

Suddenly, it's not just the night fighters

who wanna know what's going on,

everyone wants to know what's going on.

What if it's the Germans?

What if this is the Axis powers creating a new weapon,

a new aircraft,

something that we don't know about

that's going to start shifting the advantage

that, at this point, the Allied powers have in the war?

A few days after the New York Times article,

the AP Science editor writes another article

that puts out this theory

that maybe what the German army has done

is put an electric charge over all of its occupied territory

that would disrupt anything flying into it.

And there's a suggestion that these balls of light

are basically latex balloons

that might be getting dragged along

in the wake by these fighters

and moving through this electrified airspace.

It kind of sounds a little crazy,

but there was an occasion where another air crew,

shortly before all this Foo Fighter business took off,

actually encountered

what looked like hundreds of small latex balloons

in the skies over occupied Euro.

Thunderbolt pilots report seeing

about a hundred yellow balloons

approximately one-foot in diameter

at an altitude of two to 3,000-feet.

Seeing these yellow latex balloons by day,

and these similarly-sized orange balls of light by night,

makes the theory seem very plausible.

While some in the military

suspect the Foo Fighters may merely be latex balloons,

others fear that the pilots are catching glimpses

of something far more powerful and deadly.

Hitler's putting an enormous amount of resources

into wunderwaffen or "wonder weapons."

Essentially, he's hoping that Germans

will make a breakthrough to create a war-winning weapon

that will destroy Allied forces.

One such super weapon

is the terrifying V-2 rocket.

The V-2 ballistic missile

was the world's first long-range ballistic missile;

in fact, it goes farther, it launches higher,

it carries a bigger payload than any of the rockets

that anyone has experienced before.

And in Hitler's arsenal,

he calls this one the vergeltungswaffen,

"the vengeance weapon."

London after a V-2 raid,

the Nazi vengeance weapon,

which in six months killed or maimed 9,000.

The worst attack by a V-2 occurs when a V-2 rocket

hits a department store in London killing 168 people.

Between September of 1944 and March of 1945,

Nazi Germany launches over 3,000 V-2 rockets.

They're especially effective

against targets in Belgium and France

and in the United Kingdom,

because the weapons move at such high-speed

that Allied forces have absolutely no weapon system

that can stop them.

The supersonic V-2 rockets

are unlike anything Allied pilots have seen before,

especially as the V-2's streaked through the night sky.

The V-2 are powered by a mixture of alcohol

and liquid oxygen.

And what's interesting about that

in relation to the Foo Fighters

is that, at night, the plume is a sort of yellowish-orange;

so if a pilot saw it perhaps from a long way off,

they would see a sort of yellowy-orange streak of light,

and they might think that this was an object tracking them.

But the V-2s aren't the only Nazi super weapon

that leaves fire in its wake.

The Komet rocket

is one of Hitler's most touted wonder weapons.

Traveling at 600 miles per hour,

these vehicles were the only rocket-powered planes

ever used in battle.

At about the time that these Foo Fighter reports

were coming in,

there were apparently several hundred

of these Komet rocket aircraft in production.

These planes are highly maneuverable,

and they can rapidly climb to 30,000 feet,

before descending to intercept enemy airplanes.

What was powering this rocket plane

was a mixture of liquid hydrogen peroxide,

methane, and water.

And when it went off,

what it created was this huge amber plume

that would appear behind the jets.

If you're a pilot looking out,

and you're seeing this mixture of rocket fuel burning,

it would look unlike anything you had ever seen before.

This fiery plume coming out of the rear of this thing

could be mistaken for the so-called Foo Fighters.

Foo Fighter sightings by the 415th Night Fighter Squadron

continue into the spring of 1945,

then vanish just as victory is declared in Europe.

The timing fuels speculation that the Foo Fighters

were a secret Nazi weapon,

but what kind remains a mystery.

The war ends in Europe in May of 1945,

but it is still ongoing in the Pacific against Japan.

Flight crews in bombers, the B-29s,

which fly at higher altitudes,

longer distances across water,

they're starting to report the same kind of lights,

similar to the Foo Fighters

that the 415th Night Squadron had seen.

The pilots are reporting

that there are these balls of fire coming up at them

and hanging on their tails as they fly over Japan.

The colors seem to shift from orange to red to

white in kind of a cyclical pattern.

And even though these balls of light or fire

never seem to offer any kind of attack,

they seem dangerous.

There's one occasion where a pilot

is being chased by one of these things,

and he goes into a cloud bank

that would give this thing the slip,

and he comes out of the cloud

and this thing is still right there on his tail.

The pilot describes this giant orange ball

about three-feet in diameter

that's just sitting about 500 yards off of his wing;

and it keeps up with him

and then vanishes in the dawn light.

Several B-29 pilots

say that if they use evasive maneuvers,

they can escape these balls of fire,

but if they're flying steadily on course,

which is what you do on a bombing run,

those balls of fire are right behind them,

and they can't lose 'em.

Some argue that these encounters

with Foo Fighters in the Pacific

indicate that the Nazis may have shared

their secret weapon technology with their Japanese allies

as the war drew to a close.

These sightings give credence to the idea

that whatever the objects are,

they might be a part

of the Axis power's last-ditch defensive effort.

Once the Nazi regime falls,

Allied scientists rushed to uncover evidence

that these advanced secret weapons actually existed.

May, 1945, Allied scientists took possession

of a number of prototype weapons

that the Nazis had been developing

in secret military installations deep in the Black Forest.

The Associated Press has an article come out

in August 20th, 1945,

and it reports that British and American scientists

have found more of Germany's weapons,

including a giant bazooka that could fire accurately

at a target over 120 miles away.

There was also something called a Spider Bomb,

a sort of air-to-air missile

that could be fired from a long distance away,

perhaps 15 miles, using a wire to guide it.

None of these experimental weapons

ever got past the prototype phase,

but by the time the 415th Squadron

is flying in the skies over Germany,

there's a possibility that the Axis forces

are just throwing everything they've got at the Allies

and just hoping for a miracle.

One possible miracle weapon Allied pilots may

have seen was allegedly kept a secret for decades.

In 1968, Renato Vesco,

an Italian aerospace engineer, writer,

comes out and reveals that he has had contacts

with high officials in the German Luftwaffe

and the German army

presenting information about these German wonder weapons

that have been held secret ever since World War II.

Renato Vesco claims that the Germans had produced

what he called the "Feuerball,"

which was a device powered by a jet engine.

This was essentially a self-propelled fireball

that could be launched into the sky

to either disrupt or destroy Allied aircraft.

The plan was that they would get close enough

and emit some sort of electromagnetic pulse

that would wreck the plane's radar system

and might bring it down.

One witness claimed that when fired during the day,

it looked like a shiny disc spinning on its axis,

but if you fired it at night,

it looked like a burning globe.

Vesco also claims

that due to advanced engineering,

these devices were invisible to radar.

What Vesco says is that in addition,

they had the ability when disengaging

to go vertically very rapidly,

which is exactly what the 415th pilots were witnessing.

Vesco claims that this fireball, feuerball, program

was based in the Black Forest,

the area that the 415th Night Fighter Squadron

was patrolling and operating.

However, skeptics point out

that there's actually no hard evidence

that these weapons were in development and production

in the area where the 415th

was reporting Foo Fighter sightings.

But it is interesting to speculate

on the types of weapons that the Germans

might have thrown into the sky at that time.

More than a hundred Foo Fighter encounters

are reported during World War II.

Many of these accounts describe strange lights

moving in ways unlike any known aircraft or weapon,

leaving some to wonder whether these objects

were actually in the sky at all.

World War II was really the first non-stop war.

It was 24/7, as much fighting at night as at day,

obviously, the night fighters, night bombing raids,

and people were exhausted, physically and mentally.

There are lots of advantages to fighting at night,

especially in the air,

but this means that the service people

that are fighting overnight

are subject to sleep deprivation,

including members of the 415th.

In an ideal world,

these pilots would have at least one rest day

between missions,

but with manpower shortages being what they were,

a lot of these people were just flying constantly

night after night after night.

When it comes to the reports by pilots

of Foo Fighter encounters,

could it be that extreme fatigue and combat stress

were playing tricks on the airmen's minds?

Experts say that these factors

could mess with perceptions of reality,

but given the very large number of encounters

and the fact that these fighters are trained

to fight at night,

it seems unlikely that all of these sightings

were due to fatigue and stress.

Knowing what we now know,

it's intriguing to speculate

that these Foo Fighter sightings might have been triggered

by something else.

These pilots that we're talking about

were exhausted quite often, but they had to overcome this.

They couldn't take a nap while they were flying,

they needed to stay awake, they needed to stay alert,

and they needed a tool to get there.

An awful lot of aviation personnel operating at

night were doing so under the influence of drugs.

The Germans were the first to rely

upon the use of amphetamines to basically drive their troops

beyond the normal limits of human endurance.

In the early stages of the war,

the Germans experienced great success

with this new tactic that they have developed

that is nicknamed Blitzkrieg, "lightning war."

The idea is to press a breakthrough so fast and so hard

that it leaves the enemy with no recourse

but to beat a hasty retreat.

In 1939,

as Germany begins a Blitzkrieg onslaught across Europe,

soldiers are given large quantities

of a powerful amphetamine called Pervitin

to fuel their rapid advance.

Their mental acuity goes up, they're able to stay

awake, and it also boosts confidence, it boosts

aggression, it makes them into better soldiers.

And at one point in the 1940s,

the British discover a downed German plane;

and in it, they find these amphetamines,

and they realize this is what's powering the German forces,

maybe it could be powering the Allied forces as well.

In response, American pilots

also begin using amphetamines.

You might not hear about this in history class,

but by late 1943,

the US Army Air Force is distributing millions of tabs

of the powerful stimulant Benzedrine sulfate

to personnel who will conduct night flights

in both bombers and fighters to men

who the army needs to stay awake and alert

under conditions of almost total darkness.

By the time the Foo Fighter sighting start in 1944,

the US has handed out over 70 million of these tablets.

The men called these go-pills

with the idea that it was basically speed,

this is going to keep them hyped up.

We don't have documentation

about if the 415th was actually using these pills,

but overall, the evidence suggests

that about 15% of American fighter pilots

were using these pills.

But there's a downside

to the continuous use of these amphetamines.

The Nazis soon figured out that this wasn't

good for their soldiers.

It made them too aggressive, it made them too paranoid,

they had too many problems.

So they declared it was a dangerous drug,

and they stopped giving it to their troops.

People get addicted and then start to take too

much of it.

And if you take too much of these particular drugs,

you get symptoms such as delirium, panic attacks,

paranoia, hallucinations,

exactly the sort of thing that might make you mistake

an innocuous light in the sky

for something rather more unusual and extraordinary,

like Foo Fighters.

There's a standard set of side effects

associated with the use of Benzedrine sulfate,

and one factor that often gets overlooked in all of this

is that there is an individual variability.

And what that means is that you give the drug to 10 people,

all 10 of them will experience the drug

in completely different ways,

some of them will hallucinate, some of them will not.

And this provides a powerful explanation

for why some people report

seeing these glowing balls of light

and others don't.

When Foo Fighters gained global attention In 1944,

the term UFOs had not been coined yet

and tales of extraterrestrial encounters

were mere science fiction.

But a few years later, all that changes

when a possible alien spacecraft sighting

becomes national news.

On June 24th, 1947,

just a couple of years after the war,

there's a private pilot near Mount Rainier

who reports that he has seen a number of flying discs.

Kenneth Arnold's vivid report

instantly becomes a media sensation.

The press called them flying saucers.

The pilot himself was like,

"Hey, I never said they were flying saucers,"

but we got that term coined for us

in that year of 1947.

Suddenly, people all across America

are claiming to see unexplained objects

flying in the skies overhead.

The frenzy only gets worse later in the year

when the military reports having recovered

some form of unidentified flying object

near Roswell, New Mexico.

Something came down near Roswell Army Airfield,

and the military put out a press release

harking back to Kenneth Arnold sighting

over Washington State,

and said, "We have recovered one of these flying saucers."

Within 24 hours, they changed their story and said,

"It had been just a weather balloon,"

but it was too late,

the story had gone all around the world.

And these two incidents,

Kenneth Arnold's flying saucer sighting

and Roswell could be said to be the birth

of the modern UFO phenomenon.

The UFO craze that's kicked off after Roswell

reignites interest in the wartime Foo Fighter sightings,

and it causes some to wonder

if there is an alien presence out there,

and whether or not they might explain

the wartime Foo Fighter phenomenon.

UFO fears are heightened in the summer of 1952

with a mysterious sighting over Washington, DC.

On Saturday, July 19th, 1952,

air-traffic controllers at Washington National Airport

reported seeing about 10 different unidentified orbs

hovering above the city.

This became an overnight story.

You're talking about these orbs

that are moving at fast pace.

So the fighter jets were sent out,

and they were reporting that these orbs,

they were moving 600 miles per hour.

These UFO sightings by air-traffic controllers

are a national story.

But the next weekend,

another dozen orbs are spotted in the skies

over the DC region, feeding the UFO frenzy.

People across the country are talking about UFOs,

they're worried about them, they're wondering about them,

and they're reporting them everywhere.

The Air Force convenes a press conference

and announces that there's nothing to fear,

but a lot of people aren't convinced,

they think that the Air Force is covering something up.

We're in the Cold War

and in arms race with the Soviet Union,

and the CIA's job is to determine

whether or not these UFO sightings

are something that we actually need to be concerned about.

So in 1953, the CIA brings together a scientific committee

that it calls the Robertson Panel

to investigate all of these UFO sightings.

The conclusion they come to,

it's a bit of a letdown.

They basically end up saying

all of these different things

are misidentification of known aerial presences,

known phenomena,

might be a weather situation

that somebody interpreted wrong.

But there's one series of sightings

the Robertson Panel can't explain.

The one holdout that even the CIA recognizes

is the Foo Fighters.

They allow that some accounts simply defy explanation,

and, in fact, they even say,

"Had the term flying saucer existed in 1945?"

That is undeniably what the Foo Fighters

would've been called.

The lack of a satisfactory explanation

from the government gives rise to imaginative speculation

about what the World War II Foo Fighters were

and where they came from.

For the believers, the Foo Fighters

really were just the start

of what has become an ongoing engagement

with unidentified flying objects.

And as recently as 2024,

we have reports from pilots flying in Oregon

of lights incredibly similar

to the way that Foo Fighters are described,

and, in fact, the air-traffic controllers,

when they're called in,

the pilots, of course, are asking,

"What is in the sky with me?",

just as Ed Schlueter was asking

when he was flying his Bristol Beaufighter,

and the reply from the base comes back,

"It's a UFO."

Nick] Some UFO believers

say that these things must be extraterrestrial,

and that they were probably drawn to Earth

to witness firsthand one of the most cataclysmic

and high-technology wars in human history.

Skeptics have suggested

that the Foo Fighter encounters of World War II

might have been hallucinations,

but the dozens of airmen who reported those sightings

strongly reject that theory.

These are men known for their bravery, their judgment,

and their keen eyesight;

they insist that what they saw was really there.

Some people who've looked at the Foo Fighter mystery

believe right from the outset

that these strange balls of light

might have a natural explanation.

Civilian and military pilots are well aware

of this weather phenomenon that's called St. Elmo's fire,

which is an atmospheric weather condition

that's produced by electrically charged ions

that discharge into the air;

and this can sometimes occur

along the wings of an aircraft in flight at night,

it sometimes looks like balls of flame.

Most experts believe that St. Elmo's fire

is unlikely to explain the Foo Fighter sightings

during the Second World War,

but a related atmospheric phenomenon might.

What gives St. Elmo's fire its glow is plasma.

Plasma is described as the fourth state of matter;

so we have solid, liquid, gas, and we have plasma

Plasmas are what occur when you add energy to a

gas and that rips electrons off of the atoms,

and now you end up with positively charged ions

and negatively charged electrons.

When lightning strikes, the illumination is due to plasma.

Plasma is the most abundant form of matter

in the universe.

The Aurora Borealis, or Northern Lights,

is a naturally occurring display

of plasma physics in action.

It's plasma that produces naturally

amazing sights.

And some believe that plasma

could be a potential explanation for the Foo Fighters.

Even in the 21st century,

we're not certain what plasma balls are, how they form,

or why they behave the way they do.

There are some scientists that claim

that they seem to act almost like living organisms.

Plasma balls are a clear sphere.

Inside, you have a mixture of noble gases like neon

interacting with high-voltage electrodes.

Once that electric current moves through the gas,

it emits a light,

and that's what you see glowing with plasma balls.

Sometimes they grow in size,

sometimes they split into multiple parts,

they interact with each other,

and they interact with the environment.

Plasmas can also take on different shapes

and they can move in different ways,

with some plasma balls moving quickly

and others appearing to just float in space.

Most documented plasma ball sightings

have occurred high above the Earth in the thermosphere.

In 1965, two astronauts on the Gemini 4 orbiter

reported a strange metallic object approaching their craft.

Six months later, the famed astronaut, James Lovell,

reports seeing a bogey at 10 o'clock on another mission.

Decades after Lovell's report,

shuttle missions being conducted into low Earth orbit

on 10 separate occasions

captured images of huge plasma blobs.

Scientists believe these same plasma balls

occasionally descend into the lower atmosphere

shared by aircraft.

And what happens when plasma comes in contact

with flying manmade objects

may explain the Foo Fighter sightings.

These plasma balls exist almost entirely

in the thermosphere,

but they've been known to be drawn downwards

through some sort of electromagnetic presence.

Plasmas can also occur around manmade objects

zipping through the sky

and emitting their own electromagnetic energy.

So you have these planes that are manmade objects

moving through this electric field.

This can help those plasma balls to form.

The Bristol Beaufighters themselves,

moving through the sky,

would've generated their own electrostatic field

to create the conditions under which these plasma balls

might come from the thermosphere into our atmosphere.

And this ties in perfectly with the way the Foo Fighters

are described by the airmen who saw them

as being drawn towards the planes,

almost like they're investigating

or attaching themselves to them.

According to the research, when this happens,

these plasma balls have been known to "toy with" military

and civilian aircraft.

The Foo Fighters were variously described

as silver, white, or red, but often pulsing and glowing,

and this is a very common feature of plasmas.

The phenomenon is visually astonishing

and attention attracting,

because when it's being played out,

you see visible balls of fire around the aircraft

while it's flying.

In 2020,

a study by scientists at Cornell University

connects advanced technology aboard the night fighter planes

to the appearance of plasma balls.

The idea is that these planes

that the Night Fighters were flying,

the way that their radar worked

was that it was pulsing,

and it pulsed so that it wouldn't overheat

all of the equipment.

The radar signals that were sent out by these

airplanes were very strong signals,

'cause they had to travel miles

and then reflect back to the airplane

for them to get a signal.

Sending that strong radio signal

through the exhaust from the plane, ionizing that gas,

could easily have formed a plasma ball.

And any fireballs that were created

would then stay next to the plane.

And so, as the plane maneuvers,

the fireball would maneuver along with it,

and so, that would match exactly what the pilot saw

when they were observing the Foo Fighters.

Since Foo Fighters were first sighted

in November of 1944,

American military personnel and civilians alike

have developed a host of theories

to explain the Foo Fighter mystery.

While some theorists believe the Foo Fighters could be UFOs,

or the result of some obscure meteorological phenomenon,

others propose a more conventional explanation.

The common denominator

with all of these Foo Fighter encounters

is that they happen at night,

and that was a new environment for the pilots

of the 415th Night Fighter Squadron.

To keep from being spotted,

the pilots used airplanes that were painted black

and even had darkened instrument panels.

So these pilots, when they're flying,

yes, they're looking at their instrument panel,

yes, the radar operator's looking at the radar,

but they're also staring out into the darkness

with very few other lights around them

trying to see what they can make sense of,

and this is an incredibly disorienting experience.

Flying at night with a moonless sky

with very few reference points and clouds coming over them,

maybe the pilot's eyes were just playing tricks on them.

Back in 1799,

exploring scientist, Alexander Von Humboldt,

was out at night and he reported that he started to see

the stars swing around in the sky.

He used the term sternschwankung, swinging stars,

to describe these.

And it wasn't until almost a hundred years later

that science was able to show

the stars aren't actually moving.

What's happening in the night sky

is actually a pretty common phenomenon

known as autokinesis.

Autokinesis is a visual illusion

where a stationary light source,

set against a very dark background,

can appear to be moving.

This could be a problem for pilots

because it creates the illusion that a stationary light

could be on a collision course with their airplane.

In February, 1945,

The War Department actually sets up an experiment

to try to determine whether autokinesis

is the source of the Foo Fighter reports.

They put together an experiment within a simulated cockpit

of one of these Bristol Beaufighters.

They were in this pitch-black room,

and you have this one little light

that's being shined right in their eyes.

The pilots would stare at that single source of light

with no reference around them.

And with the passage of time,

they would eventually begin to hallucinate

that the light was moving;

it would swing from side to side,

it would approach them, it would retreat away from them,

and all of it was in their head.

During the experiment that they conducted,

it only took six to 12 seconds for this optical illusion

to take place.

When a pilot is flying a plane,

that plane is rolling and pitching and yawing

and moving through space,

that movement alone is enough to create a sense

that a stationary light outside of the plane

is actually the thing doing the moving.

Even the best pilots can get confused

and see things that aren't there,

and that's something that even happens today.

As recently as 2011,

a pilot flying a commercial plane caused major havoc

when he mistook a planet for an oncoming aircraft.

A 767 was en route from Toronto to Zurich.

The co-pilot had been informed

that there was a cargo aircraft in his vicinity,

and so he should maintain awareness

for the possibility of its presence.

The co-pilot saw a light that was coming towards him,

and mistakenly identified it as cargo aircraft.

To avoid hitting that bright light

that the pilot thought was coming at them,

they decided to take a nose dive.

Thankfully, the captain took over,

and it was not a deadly crash,

but it almost hit the actual cargo plane

that was in the area about a thousand feet below the 767.

Later investigation demonstrated

that what he was seeing was actually the planet Venus

60 million miles away.

We have almost limitless amounts of information

about pilots becoming confused in the sky.

Once that disorientation sets in,

it's very difficult for a pilot to overcome it

and regain situational awareness.

This kind of disorientation

means that pilots that are flying straight

feel like they're turning,

or even worse, they're so disoriented,

they think that they're upside down

when they're actually flying right side up

because of the lights and things that they're seeing.

So with all this aerial clutter

that they were seeing in World War II,

this could account for the Foo Fighters.

Is it possible the Foo Fighter witnesses

were misled by stray lights in the sky?

Some say that might be the case.

Proponents of this theory

feel that this autokinesis phenomenon

is an incredibly powerful illusion

that these airmen were never trained on.

According to a night fighter commander

who was interviewed after the war,

his men were never trained on misperceptions or illusions

or disorientation that could occur

during night air fighting.

So these pilots racing over Germany at night,

you can see where the power of suggestion

overrides rational thought.

For the men who encountered the Foo Fighters

in those closing years of World War II,

this remained an experience

that was to them profound and unforgettable.

It was something that would be with them

for the rest of their lives.

Maybe it was a German weapon that's been lost to time,

maybe it is something literally beyond our understanding.

It was certainly the origin of UFO stories;

and to true believers,

that final chapter has yet to be written.

Whether the Foo Fighters

were created by a state of matter, a state of mind,

or something otherworldly,

we may never know the complete truth

about what or who the Foo Fighters really were,

or if they actually existed.

I'm Laurence Fishburne,

thank you for watching "History's Greatest Mysteries."