All language subtitles for spaces.deepest.secrets.s05e01.720p.hdtv.x264-w4f[eztv]

Narrator: THE MOON --
EARTH'S NEAREST NEIGHBOR,

BUT ONE OF THE MOST MYSTERIOUS
OBJECTS IN THE SOLAR SYSTEM.

IF YOU ACTUALLY WANT TO LOOK AT
ONE OF THE GREATEST MYSTERIES

OF THE UNIVERSE RIGHT NOW,
JUST LOOK UP AT THE MOON.

Narrator: FOR DECADES,
SCIENTISTS WERE SURE

THEY'D SOLVED MANY OF
THE MOON'S DEEPEST SECRETS.

BUT NOW, NEW EVIDENCE SUGGESTS
THAT NEARLY EVERYTHING

WE THOUGHT WE KNEW
ABOUT THE MOON COULD BE WRONG.

WE MIGHT NEED
TO COMPLETELY RETHINK

OUR UNDERSTANDING
OF THE FORMATION OF THE MOON.

Oluseyi: IMAGINE IF YOU COULD
HAVE LOOKED UP AT THE NIGHT SKY

AND SAW TWO MOONS.

THAT WOULD'VE BEEN LIT!

♪♪

Narrator:
WHY IS OUR MOON SO BIG?

WHY DOES IT LOOK SO STRANGE?

AND WHY IS THE NEARSIDE

SO TOTALLY DIFFERENT
FROM THE FAR SIDE?

♪♪

TODAY, PIONEERING TECHNOLOGY
COULD FINALLY REVEAL ANSWERS.

Z IS PREPARING TO FIRE.

Narrator:
THIS IS THE INSIDE STORY

OF THE RACE TO UNRAVEL

THE MYSTERIES OF OUR MOON.

♪♪

-- Captions by VITAC --
www.vitac.com

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

♪♪

Narrator: THE MOON --

SINCE MANKIND FIRST LOOKED UP
TO THE SKY,

IT'S BEEN THERE, LOOKING BACK.

IT REMAINS THE ONLY PLACE
BEYOND OUR HOME PLANET

WHERE HUMANS HAVE SET FOOT.

Neil Armstrong:
THAT'S ONE SMALL STEP FOR A MAN,

ONE GIANT LEAP FOR MANKIND.

Narrator: WITHOUT IT, LIFE AS WE
KNOW IT PROBABLY WOULDN'T EXIST.

THE MOON HAS BEEN THE EARTH'S
COMPANION FOR 4.5 BILLION YEARS.

IT DRIVES THE MOTIONS
OF THE TIDES,

AND THE MOTIONS OF THE TIDES

ARE INTRICATELY LINKED
TO THE CYCLE OF LIFE ON EARTH.

THE MOON IS VITAL FOR LIFE
ON EARTH.

THE MOON IS THERE

IN THE SENSE
OF A SATELLITE OF PLANET EARTH,

BUT IT'S THERE, ALSO, IN A SENSE
OF ALLOWING LIFE AS WE KNOW IT

TO HAVE THE FEATURES
THAT WE EXPERIENCE.

Narrator:
AS IMPORTANT AS THE MOON IS,

SCIENTISTS NOW KNOW
THAT IT'S ALSO EXTREMELY WEIRD.

THE FIRST CLUE
IS ITS SURPRISING SIZE.

IF THERE WERE
AN ALIEN ASTRONOMER

FROM ANOTHER SOLAR SYSTEM,

I THINK THEY WOULD COME
TO OUR PLANET

AND LOOK UP AT THE MOON
WITH ASTONISHMENT.

Oluseyi: THERE'S SOMETHING
ABOUT OUR MOON

THAT MAKES IT
INCREDIBLY STRANGE.

IT'S JUST TOO DARN BIG.

Plait: OF ALL THE MAJOR PLANETS
IN THE SOLAR SYSTEM,

EARTH HAS THE BIGGEST MOON

RELATIVE TO
THE SIZE OF THE PLANET,

AND THAT'S VERY, VERY STRANGE.

Narrator: LARGE MOONS ARE RARE
AMONGST THE ROCKY PLANETS

IN OUR SOLAR SYSTEM.

♪♪

MERCURY AND VENUS
HAVE NO MOONS AT ALL.

♪♪

MARS HAS TWO TINY MOONS,
DEIMOS AND PHOBOS,

MANY HUNDREDS OF TIMES SMALLER
THAN THEIR HOST PLANET.

IT'S THOUGHT THEY WERE
ONCE ASTEROIDS

THAT MARS ENSNARED
WITH ITS GRAVITATIONAL PULL.

BUT EARTH'S MOON IS A FREAK.

OVER 2,100 MILES ACROSS,

WEIGHING IN AT
77 MILLION TRILLION TONS,

IT'S MORE THAN A QUARTER
THE SIZE OF EARTH,

FAR TOO BIG TO BE
A CAPTURED ASTEROID.

HOW DID WE GET
THIS GIANT COSMIC COMPANION?

SCIENTISTS THINK THAT THE MOON
MUST HAVE BEEN FORMED

BY AN EVENT OF
EXTRAORDINARY VIOLENCE.

Oluseyi: WHEN YOU LOOK
AT THE SURFACE OF THE MOON,

ONE THING YOU CAN SEE
IS THAT IT'S BEEN HIT A LOT,

BUT MAYBE IT WAS CREATED
FROM THE BIGGEST HIT.

Narrator: FOR OVER 30 YEARS,
ONE THEORY FOR THE NATURE

OF THIS VIOLENT BIRTH
HAS RULED SUPREME.

IT'S CALLED
THE GIANT-IMPACT HYPOTHESIS.

THE MAIN IDEA
OF HOW THE MOON FORMED

WAS THAT SOMETHING CAME IN,
SMACKED THE EARTH,

BITS FLEW EVERYWHERE,
AND THEY EVENTUALLY RECONDENSED,

FORMING THE MOON
AS WE SEE IT TODAY.

Narrator:
4.5 BILLION YEARS AGO,

WHEN EARTH IS STILL
A SCORCHED BALL OF HOT ROCK,

ANOTHER YOUNG PLANET
CALLED THEIA

COMES TOO CLOSE FOR COMFORT.

AS IT STRIKES THE EDGE
OF THE EARTH AT AN ANGLE,

TRAVELING AT MORE THAN
26,000 MILES PER HOUR,

THEIA RIPS OFF
THE TOP OF THE EARTH.

THE DEBRIS FORMS A RING...

...AND OVER TIME,

THE FRAGMENTS FUSE TOGETHER
INTO A BALL OF SCORCHING ROCK

THAT EVENTUALLY BECOMES
OUR MOON.

♪♪

SCIENTISTS WANT TO INVESTIGATE

IF THIS ESTABLISHED THEORY
IS CORRECT.

IF THE GIANT-IMPACT HYPOTHESIS
IS TRUE,

THEN WE SHOULD BE ABLE
TO FIND EVIDENCE.

Narrator: SO THEY REVISIT CLUES

FIRST GATHERED
OVER 45 YEARS AGO.

IN THE 1960s AND '70s,

APOLLO ASTRONAUTS COLLECTED
OVER 830 POUNDS OF MOON ROCKS.

Harrison Schmitt:
That boulder's gonna roll.

Man, that is hard.

Just don't stub your toe.

Narrator: SCIENTISTS THINK
THAT THESE ROCKS

COULD HOLD THE ANSWER...

Gene Cernan: It's orange!

...AS TO WHETHER
THE CONVENTIONAL THEORY

OF HOW THE MOON FORMED IS RIGHT.

♪♪

♪♪

EDWARD YOUNG IS A GEOCHEMIST.

HE'S GOT HIS HANDS ON
A PRECIOUS SAMPLE OF MOON ROCK.

♪♪

Young: WE GET SAMPLES LIKE THIS
FROM JOHNSON SPACE CENTER.

WE REQUEST A MILLIGRAM OR LESS.

THAT'S ALL WE NEED, REALLY,
TO MAKE AN ANALYSIS.

THIS PARTICULAR SAMPLE COMES
FROM THE APOLLO 16 MISSION.

IT WAS BROUGHT BACK
BY THE ASTRONAUTS.

Narrator: IF THE CONVENTIONAL
THEORY IS CORRECT,

AND THEIA COLLIDED WITH
THE EARTH IN A GLANCING BLOW,

THEN THE MOON SHOULD BE
MOSTLY MADE OUT OF THEIA.

IT MEANS THAT MOON ROCK SHOULD
BE CHEMICALLY DIFFERENT

THAN EARTH ROCK.

ED DESIGNS EXPERIMENTS TO TEST
THIS PREDICTION.

IN HIS LAB, ED HAS THE LARGEST
AND HIGHEST RESOLUTION

MASS SPECTROMETER
OF ITS KIND IN THE WORLD.

THE MACHINE ANALYZES THE OXYGEN
THE ROCKS CONTAIN.

EVERY SOLAR SYSTEM BODY

HAS ITS FINGERPRINT
OF MOLECULAR WEIGHT OF OXYGEN.

THEIA SHOULD'VE BEEN DIFFERENT
FROM EARTH,

AND IF THEIA IS MOSTLY
IN THE MOON,

WE SHOULD EXPECT TO SEE THE MOON
HAVING A SLIGHTLY DIFFERENT

MOLECULAR WEIGHT OF OXYGEN
THAN THE EARTH.

Narrator:
ED'S COLLEAGUE USES A LASER

TO PREPARE A SAMPLE
FOR ANALYSIS.

THE LASER MELTS THE ROCK

AND CAUSES IT TO REACT
WITH A CHEMICAL

WITHIN THE CHAMBER,
RELEASING OXYGEN GAS.

WHAT MOST PEOPLE DON'T THINK
ABOUT IS THAT ROCK

IS MOSTLY OXYGEN.
IT'S 90%, BY VOLUME, OXYGEN,

AND IT'S ABOUT HALF,
BY WEIGHT, OXYGEN.

AND SO WHEN WE HEAT THE SAMPLE

AND MELT THE SAMPLE WITH
THE LASER BEAM,

THAT LEAVES US,
WHEN WE'RE ALL DONE,

WITH JUST OXYGEN REMAINING
AS OXYGEN GAS,

AND THE OXYGEN GAS IS WHAT
WE ANALYZE.

THE OXYGEN ACTS AS A UNIQUE
IDENTIFIER,

THE CHEMICAL FINGERPRINT
OF THE ROCK.

ED COMPARES THE CHEMICAL
FINGERPRINT OF THE MOON ROCKS

TO EARTH ROCKS.

THE BIG QUESTION --
ARE THEY DIFFERENT AS PREDICTED?

WELL, IN THIS PLOT,
WE'RE LOOKING AT OUR RESULTS

FOR SAMPLES FROM THE EARTH
AND SAMPLES FROM THE MOON.

AND ON THIS AXIS OF THIS PLOT,

WE'RE SEEING THE REAL
FINGERPRINT OF THE OXYGEN

THAT MAKES UP THESE BODIES.

IF THE COLLISION THAT FORMED
THE MOON LEFT MORE

THEIA IN THE MOON
THAN IT DID IN THE EARTH,

WE WOULD EXPECT THERE TO BE
AN OFFSET,

AND WHAT WE'RE SEEING
ON THIS PLOT

IS THAT THERE'S
NO RESOLVABLE DIFFERENCE

BETWEEN THE TERRESTRIAL SAMPLES
FROM THE EARTH

AND THE LUNAR SAMPLES.

Narrator:
THE RESULT IS SURPRISING.

THE MOON AND EARTH ROCKS

HAVE VIRTUALLY
IDENTICAL CHEMICAL FINGERPRINTS.

IT FLIES IN THE FACE
OF THE CONVENTIONAL THEORY

OF HOW THE MOON FORMED.

♪♪

YOU HAVE THIS OBJECT, THEIA,

THAT IMPACTS WITH THIS
OTHER OBJECT, EARTH,

AND THEN IN THE END,
YOU HAVE TWO OBJECTS,

THE EARTH AND THE MOON,

THAT ARE NOW COMBINATIONS
OF EARTH AND THEIA.

THE PROBLEM IS, IS THAT WE CAN'T
FIND EVIDENCE OF THEIA.

Tremblay:
IT'S LIKE STUMBLING UPON

A SITE OF A MASSIVE COLLISION

BETWEEN WHAT YOU KNOW
IS TWO CARS,

BUT YOU CAN'T FIND
THE OTHER CAR.

Narrator: SO IS
THE ENTIRE THEIA HYPOTHESIS

JUST PLAIN WRONG,
OR DOES THE STANDARD THEORY

JUST NEED REWORKING
FOR THE EARTH AND THE MOON

TO END UP WITH VIRTUALLY
IDENTICAL CHEMICAL FINGERPRINTS?

ONE SCIENTIST MIGHT JUST HAVE
THE ANSWER.

NOTHING COMES CLOSE TO REALIZING

THAT YOU'VE FOUND SOMETHING

THAT NO ONE HAS
EVER THOUGHT OF BEFORE.

Narrator: AND SHE'S READY TO PUT
A RADICAL NEW IDEA TO THE TEST.

♪♪

♪♪

Narrator: THE MOON --

ONE OF THE STRANGEST OBJECTS
IN THE SOLAR SYSTEM.

ASTRONOMERS ARE IN A RACE
TO UNLOCK THE SECRETS

OF ITS MYSTERIOUS ORIGIN.

THEY ARE CONVINCED
THE CONVENTIONAL MODEL

FOR HOW THE MOON FORMED
IS FLAWED.

BUT IS IT COMPLETELY WRONG?

ASTROPHYSICIST SARAH STEWART
BELIEVES THAT THE BASIC IDEA

OF THE GIANT-IMPACT HYPOTHESIS
IS STILL CORRECT,

BUT WITH ONE CRUCIAL DIFFERENCE.

INSTEAD OF HITTING THE EARTH
IN A GLANCING BLOW,

THEIA COULD'VE
SLAMMED RIGHT INTO IT.

THE ENERGY OF THE COLLISION
PARTIALLY VAPORIZES

THE TWO PLANETS,

MIXING THEM TOGETHER TO CREATE
A SUPERHEATED CLOUD

OF LIQUEFIED ROCK AND GAS
CALLED A SYNESTHESIA.

AS THE SEETHING MASS COOLS,

DROPLETS OF
MOLTEN ROCK FUSE TOGETHER

AND GRADUALLY GROW BIGGER.

OVER JUST A FEW DECADES,

MATERIAL FROM
THE TWO VAPORIZED PLANETS

KEEPS MERGING AND MIXING,

AND THE SYNESTHESIA SHRINKS
UNTIL IT GIVES BIRTH TO THE MOON

AND, CRUCIALLY, A REBUILT EARTH
MADE FROM THE SAME MATERIAL.

THERE ARE SCIENTISTS NOW THAT
THINK WHEN TWO PLANETS COLLIDE,

THE FIRST THING
THAT YOU'RE LEFT OVER WITH

IS A GIANT DOUGHNUT
OF EXTREMELY HOT ROCK.

WE'RE TALKING ROCK
THAT'S BEEN VAPORIZED.

AND OUT OF THIS ONE OBJECT,

THIS ONE BIG DOUGHNUT
OF GASEOUS ROCK,

TWO THINGS FORMED.

IN THE VERY CORE OF THIS
WAS THE EARTH,

BASICALLY THE REMNANT OF THESE
TWO PLANETS THAT COLLIDED,

AND FARTHER OUT
IN THIS HOT DOUGHNUT OF GAS,

THAT WAS WHERE THE MOON FORMED.

♪♪

Narrator:
AT SANDIA NATIONAL LABORATORIES,

SARAH USES THE Z MACHINE

TO PUT THE NEW SYNESTHESIA IDEA
TO THE TEST.

♪♪

THE Z MACHINE PRODUCES SHORT
BURSTS OF ELECTRICAL ENERGY

OF PHENOMENAL INTENSITY
FOUND NOWHERE ELSE ON EARTH.

IT WAS ORIGINALLY BUILT TO STUDY
THE PHYSICS OF NUCLEAR WEAPONS.

SARAH WANTS TO USE THE POWER
OF THE Z MACHINE TO PROVE

THAT A BIG ENOUGH IMPACT
COULD TURN EARTH AND THEIA

INTO A GIANT CHURNING CLOUD
OF VAPORIZED ROCK.

IN THIS CHAMBER,

WE ARE RECREATING
PLANET FORMATION IN THE LAB.

THE EXPERIMENTS ARE EXTREMELY
ENERGETIC,

AND SO PART OF
THE MASSIVE CHAMBER

IS TO CONTAIN ALL OF
THE DEBRIS FROM THE EXPLOSION.

Narrator: SARAH SMASHES
MATERIALS TOGETHER

INSIDE THE Z MACHINE
AND MEASURES THE POINT

AT WHICH THEY VAPORIZE.

EARTH IS REPRESENTED BY
A TINY SAMPLE OF MINERAL

THAT'S MOUNTED ONTO A BLOCK.

THEIA IS REPRESENTED
BY A METAL PLATE.

THAT STRIKES THE TARGET.

THAT GENERATE A SHOCK WAVE
THAT TRAVELS THROUGH THE SAMPLE,

EARTH, AND WE CAN DETERMINE WHEN
THE MATERIAL BEGINS TO VAPORIZE.

Narrator:
WHEN THE Z MACHINE FIRES,

IT RELEASES
A PULSE OF ELECTRICITY,

1,000 TIMES GREATER
THAN A LIGHTNING BOLT.

ATTENTION BUILDING 983.
Z IS PREPARING TO FIRE.

THE ELECTRICAL ENERGY GENERATES
A FORCE

THAT SMASHES THE SAMPLE
AND TARGET TOGETHER

AT MORE THAN 100 TIMES
THE SPEED OF SOUND.

THIS CREATES A MINI EARTHQUAKE
THAT SHAKES THE ENTIRE SITE.

WILL THE RESULTS SEAL THE FATE
OF SARAH'S NEW IDEA?

♪♪

THE HOT-OFF-THE-PRESS RESULTS
IS THAT 20% TO 30% OF THE EARTH

WAS VAPORIZED ENOUGH

TO GENERATES A SYNESTHESIA
AS WE PREDICTED.

Narrator: THE DATA INDICATES
THAT THEIA COLLIDING WITH EARTH

COULD'VE CREATED
A SINGLE, CHURNING CLOUD

OF VAPORIZED ROCK,

A SYNESTHESIA.

IT'S IN THIS HIGHLY VAPORIZED
SYNESTHESIA

THAT THE MOON FORMS AND LEADS
TO THE CHEMICAL SIMILARITY

BETWEEN THE EARTH AND THE MOON.

♪♪

THE SYNESTHESIA IDEA IS THAT
INSTEAD OF JUST THROWING

THE STUFF UP INTO ORBIT
AFTER THE IMPACT,

THE ROCK ON THE SURFACE
OF THE EARTH ACTUALLY VAPORIZED,

AND THE EARTH WAS SPINNING
VERY RAPIDLY,

AND JUST WOUND UP FORMING
SORT OF A DOUGHNUT SHAPE.

NOW THIS ACTUALLY
SOLVES A LOT OF PROBLEMS.

IT ACTUALLY SHOWS HOW THE ROCKS
ON THE MOON

COULD BE SIMILAR
IN MANY WAYS TO THE EARTH.

THEY ALL FORMED OUT OF
THE SAME CLOUD OF DEBRIS.

Narrator:
THE NEW SYNESTHESIA IDEA

IS GAINING SIGNIFICANT TRACTION

BECAUSE IT MAY ALSO HELP
TO EXPLAIN

ANOTHER OF THE MOON'S
STRANGEST MYSTERIES.

SINCE THE MOON LANDINGS,
SCIENTISTS HAVE KNOWN

THAT MOON ROCKS
HAVE MYSTERIOUSLY LOW AMOUNTS

OF PARTICULAR ELEMENTS,
SUCH AS SODIUM AND POTASSIUM.

PLANETS LIKE THE EARTH AND MARS
ARE RICH IN THESE CHEMICALS,

SO WHY NOT THE MOON?

THE EARTH AND THE MOON
ARE ALMOST CHEMICALLY IDENTICAL,

BUT NOT QUITE.

Plait: THE MOON HAS LESS
POTASSIUM AND SODIUM IN IT

THAN THE EARTH DOES,
AND THAT'S REALLY WEIRD.

YOU EXPECT THEM TO BE THE SAME.

♪♪

Narrator:
GEOSCIENTIST CATHERINE MACRIS

THINKS THAT
THE SYNESTHESIA THEORY

COULD FINALLY SOLVE
THIS DECADES-OLD MYSTERY.

I LIKE TO GO IN THE LAB AND SORT
OF CREATE MY OWN MOON.

AND WITH THE HELP OF
THE MINI MOON SHE CREATED,

SHE'S READY TO PUT
THE SYNESTHESIA THEORY

TO THE TEST.

♪♪

♪♪

Narrator:
GEOSCIENTIST CATHERINE MACRIS

IS TRYING TO FINALLY SOLVE
A DECADES-OLD MYSTERY.

IF THE MOON IS FORMED
FROM THE SAME CLOUD

OF DEBRIS AS THE EARTH,

WHY DOES IT HAVE LOW LEVELS
OF CERTAIN ELEMENTS?

CATHERINE THINKS A CURIOUS QUIRK
OF THE SYNESTHESIA THEORY

MAY HAVE ALLOWED THE EARTH

TO STEAL THE MOON'S
SODIUM AND POTASSIUM.

THE QUIRK HAS ALL TO DO
WITH TEMPERATURE

AND THE ORDER IN WHICH
IN THE EARTH AND THE MOON FORM.

HIDDEN DEEP INSIDE THE SWIRLING
CLOUDS OF THE SYNESTHESIA,

THE EMBRYONIC MOON
TAKES SHAPE FIRST.

AS IT GROWS, ITS GRAVITY SUCKS
IN MORE

AND MORE OF THE SUPERHEATED
MOLTEN ROCK AROUND IT.

THE SURFACE OF THE YOUNG MOON
BECOMES SO HOT,

SODIUM AND POTASSIUM EVAPORATE
BACK INTO THE CLOUD.

THEY DRIFT AWAY
INTO THE SYNESTHESIA

IN A TRAIL OF VAPOR.

♪♪

AS THE SYNESTHESIA CLOUD COOLS,
IT SHRINKS,

EVENTUALLY FORMING THE EARTH,

COMPLETE WITH THE MOON'S
MISSING SODIUM AND POTASSIUM.

CATHERINE WANTS TO TEST
THIS IDEA.

HER EXPERIMENT RECREATES
THE HIGH TEMPERATURES

IN THE SYNESTHESIA

TO SEE THIS AFFECTS
THE CHEMICAL MAKEUP OF THE MOON.

WE HAVE A 400-WATT CO2 LASER.

THIS IS THE LASER, RIGHT HERE.

IT'S VERY BIG AND POWERFUL.

THE LASER IS ACTUALLY POINTING
STRAIGHT UP RIGHT NOW,

BUT I HAVE SOME MIRRORS
OR LENSES HERE

THAT ACTUALLY SEND IT
STRAIGHT DOWN HERE

SO THAT IT'S SHOOTING RIGHT
INSIDE OF THIS CHAMBER HERE.

Narrator: CATHERINE PUTS
A MINIATURE SYNTHETIC MOON

INTO THE METAL CHAMBER.

THE SAMPLE'S CHEMICAL MAKEUP

IS SIMILAR TO THAT OF
THE EMBRYONIC MOON

WHEN IT STARTS TO GROW
IN A SYNESTHESIA.

WHEN IT MELTS, IT'S GOING TO BE
A LITTLE, TINY BALL OF MAGMA,

BASICALLY,
FLOATING AND SPINNING.

Narrator: THE EMBRYONIC
MINI MOON LEVITATES

ON A JET OF GAS,

JUST LIKE IT'S ON
AN AIR-HOCKEY TABLE,

AND CATHERINE USES THE LASER
TO HEAT IT UP.

AS THE TEMPERATURE RISES,

THE EMBRYONIC MINI MOON
STARTS TO GLOW.

♪♪

WE CAN SEE THAT IT'S GETTING
HOTTER AND HOTTER.

Narrator: IT REACHES
OVER 3,600 DEGREES FAHRENHEIT.

THIS IS THE SAME TEMPERATURE

AS THE OUTER EDGE
OF A SYNESTHESIA CLOUD.

A TRAIL OF VAPOR SUDDENLY BURSTS

FROM THE SURFACE
OF THE MINI MOON.

CATHERINE THINKS THIS SMOKE
MAY INCLUDE

THE VITAL SODIUM AND POTASSIUM
MISSING FROM THE REAL MOON.

♪♪

IT STARTED OUT BEING
A REALLY DARK BROWN,

AND WE CAN SEE
THAT IT CHANGED COLOR.

RIGHT NOW, WHAT WE'RE SEEING
IS THAT IT'S A VERY,

VERY, VERY PALE YELLOW,
AND IT'S ALSO GOTTEN SMALLER.

Narrator: FURTHER TESTS CONFIRM
THAT THE CHEMICAL MAKEUP

OF THE MINIATURE EMBRYONIC MOON
HAS BEEN ALTERED.

IT CONTAINS LESS SODIUM
AND POTASSIUM.

THE RED LINE
REPRESENTS POTASSIUM.

THE BLUE LINES
REPRESENTS SODIUM,

AND WHAT WE SEE IS THAT
THE LONGER WE HEAT THE MELT,

THE MORE OF THIS MATERIAL
IS EVAPORATED AND THEN LOST,

AND SO WHAT WE ARE LEFT WITH
IS A MOON

THAT HAS LESS OF THOSE ELEMENTS.

♪♪

Thaller: ONE OF THE AMAZING
THINGS ABOUT THIS IDEA

IS THAT THE MOON WOULD'VE FORMED
BEFORE THE EARTH.

IN THE VERY OUTER PARTS
OF THE CLOUD,

THE SMALLER MOON FORMED,

AND MAYBE AS MUCH
AS 1,000 YEARS LATER,

THINGS FINALLY SETTLED DOWN
IN THE CORE OF THE CLOUD

TO MAKE OUR PLANET.

SO IN THE SYNESTHESIA
DEBRIS CLOUD,

THE EARTH AND THE MOON
WOULD'VE HAD

SLIGHTLY DIFFERENT
FORMATION TIMES,

WITH THE MOON FORMING
JUST PRIOR TO THE EARTH.

AND BECAUSE THEY WOULD'VE
FORMED AT DIFFERENT TIMES,

THE EARTH IS ABLE TO STEAL
THE SODIUM AND POTASSIUM

FROM THE MOON,

AND THIS COULD EXPLAIN
THEIR CHEMICAL DIFFERENCES.

Narrator: THE BRAND-NEW
SYNESTHESIA THEORY

COULD BE
SCIENTISTS' BEST EXPLANATION

FOR HOW EARTH'S MOON WAS BORN
4.5 BILLION YEARS AGO.

IT EXPLAINS WHY THE MOON
AND EARTH

SHARE ALMOST IDENTICAL
CHEMICAL FINGERPRINTS,

AND, CRUCIALLY, WHY THE MOON
HAS LESS POTASSIUM AND SODIUM.

BUT SCIENTISTS
STILL WANT TO KNOW

WHY THE MOON LOOKS
THE WAY IT DOES.

THE FAMILIAR DARK PATCHES THAT
COVER THE NEARSIDE OF THE MOON

ARE UNIQUE IN THE SOLAR SYSTEM.

WHAT ARE THEY, AND WHAT FORCES
CREATED THEM?

AND IS IT POSSIBLE

THAT THE EARTH
ONCE HAD TWO MOONS IN THE SKY?

Oluseyi: IMAGINE IF YOU COULD'VE
LOOKED UP AT THE NIGHT SKY

AND SAW TWO MOONS.

THAT WOULD'VE BEEN LIT!

♪♪

♪♪

Narrator: A NEW GENERATION
OF SCIENTISTS

ARE CHALLENGING THE ESTABLISHED
THEORY OF HOW THE MOON WAS BORN.

BUT ONE MYSTERY REMAINS
UNSOLVED.

THE FAMILIAR DARK SPLOTCHES THAT
COVER THE NEARSIDE OF THE MOON

ARE UNIQUE IN THE SOLAR SYSTEM.

WHAT MADE THE MAN IN THE MOON,

AND WHY DON'T WE SEE
SIMILAR FEATURES ON OTHER MOONS?

WE THINK OF OUR SOLAR SYSTEM

AS JUST BEING EIGHT PLANETS,
RIGHT?

BUT IN REALITY, MANY OF THOSE
PLANETS HAVE MANY MOONS,

AND THOSE MOONS HAPPEN TO BE

SOME OF THE MOST FASCINATING
PLACES IN THE SOLAR SYSTEM.

YOU'VE GOT IO, YOU KNOW,

THE SOLAR SYSTEM'S
GREATEST HELLSCAPE.

YOU'VE GOT ENCELADUS,
WHICH HAS BEAUTIFUL PLUMES.

YOU'VE GOT TITAN,
WHICH RAINS LIQUID METHANE.

AND THEN YOU HAVE OUR MOON.

OUR MOON IS UNIQUE.

IF YOU'VE EVER SEEN
"THE MAN IN THE MOON," RIGHT?

THAT FACE THAT YOU SEE
ON THE NEARSIDE OF THE MOON.

THAT DOESN'T HAPPEN ON ALL MOONS
IN THE SOLAR SYSTEM.

Narrator:
EVEN MORE MYSTERIOUSLY,

THE DARK ROCKS THAT MAKE UP
THE MAN IN THE MOON

ARE ALMOST COMPLETELY ABSENT
FROM THE FAR SIDE.

ALL OF THOSE DARK SPLOTCHES
THAT WE SEE ON THE NEARSIDE,

THEY'RE NOT ON THE OTHER SIDE.

THERE'S A HUGE DIFFERENCE
IN GEOLOGY BETWEEN THE FAR SIDE

AND THE NEARSIDE OF THE MOON,
AND THAT IS REALLY PECULIAR.

♪♪

Narrator: NOAH PETRO WORKS

AT NASA'S
GODDARD SPACE FLIGHT CENTER.

HE'S DEDICATED HIS CAREER

TO SOLVING THE MOON'S
GREATEST MYSTERIES.

♪♪

NOAH IS A PROJECT SCIENTIST

ON NASA'S LUNAR RECONNAISSANCE
ORBITER MISSION.

LAUNCHED IN 2009,
THIS ROBOT SPACECRAFT

HAS BEEN ORBITING THE MOON
EVER SINCE,

MAPPING ITS SURFACE.

NOAH THINKS THAT THE DATA
FROM THIS LUNAR PROBE

COULD HELP EXPLAIN HOW
THE MAN IN THE MOON WAS CREATED.

♪♪

WHAT WE HAVE UP HERE IS A VIEW
OF WHAT'S HAPPENING

WITH THE LUNAR
RECONNAISSANCE ORBITER,

AND SO WHAT WE HAVE
IN THIS DISPLAY

IS A SENSE OF WHAT
THE SPACECRAFT IS SEEING,

WHAT THE SPACECRAFT IS DOING.

RIGHT NOW, LRO IS JUST ABOUT
AS CLOSE TO THE SOUTH POLE

AS IT'S GONNA GET.

WE'RE PASSING ABOUT 2 DEGREES
AWAY FROM THE SOUTH POLE,

AND IN A MOMENT,
LRO WILL START PASSING

OVER THE FAR SIDE OF THE MOON.

Narrator:
NOAH'S SPACECRAFT IS EQUIPPED

WITH A SPECIAL INSTRUMENT
THAT SCANS THE MOON IN INFRARED,

A TYPE OF RADIATION
INVISIBLE TO OUR EYES.

THE SCANS SHOW
THAT THE MAN IN THE MOON

IS MADE OF ROCKS
THAT ARE RICH IN IRON,

DIFFERENT FROM THE REST
OF THE WHITE LUNAR CRUST.

THE AREAS
IN DARK RED AND ORANGE

ARE AREAS THAT HAVE
LOTS OF IRON AT THE SURFACE.

THE AREAS IN BLUE HAVE LITTLE
OR NO IRON AT THE SURFACE.

Narrator:
THE IRON-RICH ROCKS

ARE A TYPE OF SOLIDIFIED LAVA
KNOWN AS BASALT.

THE RESULTS CONFIRM
WHAT'S BEEN KNOWN

SINCE THE APOLLO MOON LANDINGS.

Petro: THE NEARSIDE OF THE MOON
IS COVERED

IN THESE MASSIVE POOLS
OF VOLCANIC ROCK

THAT HAVE ERUPTED AND FLOWED
ONTO THE LUNAR SURFACE,

COVERING MUCH OF THE NEARSIDE.

Narrator: THE EARTH'S
MOST ACTIVE VOLCANOES

SPEW IRON-RICH LAVA
ONTO THE SURFACE.

♪♪

THE MOON'S DARK PATCHES ARE MADE
IN JUST THE SAME WAY,

BUT ON A WHOLE DIFFERENT SCALE.

SOME OF THESE LAVA FLOODS ARE
THE SIZE OF AN ENTIRE COUNTRY.

IT'S AN EXTRAORDINARY
REVELATION.

FOR HUNDREDS OF MILLIONS
OF YEARS,

ONE SIDE OF THE MOON
BURNED WITH VOLCANIC FIRE...

...WHILE THE OTHER SIDE WAS
ALMOST COMPLETELY UNDISTURBED.

WHY?

THOSE DARK PATCHES ON THE MOON,
THOSE ARE POOLS OF HARDENED,

COOLED LAVA THAT FLOWED UP
4 BILLION YEARS AGO,

AND THEY'RE LARGELY CONFINED
TO ONE SIDE OF THE MOON,

THE SIDE THAT FACES THE EARTH,
AND THIS IS A REAL MYSTERY.

THESE LAVA POOLS THAT
ARE HUNDREDS OF MILES ACROSS

ARE WEIRD.

IT'S NOT CLEAR
WHERE THEY COME FROM.

♪♪

PETER SCHULTZ LOOKS FOR CLUES
IN THE MOON'S GEOLOGICAL SCARS.

BOY, I'VE BEEN INTERESTED
IN THE MOON

SINCE I WAS A KID WITH MY
TELESCOPE, SEEING THE CRATERS.

I DIDN'T UNDERSTAND.

HOW COME THERE WERE SO MANY
CRATERS ON THE MOON?

PETER THINKS THAT A GIANT
ASTEROID COLLISION

MAY HAVE LED TO THE LAVA PLAINS
ON THE NEARSIDE OF THE MOON,

AND TO PROVE IT, HE'S TAKING AIM
WITH ONE OF NASA'S LARGEST GUNS.

WE'RE GOING TO FIRE A PROJECTILE
DOWN HERE

AT 22 TIMES THE SPEED OF SOUND,

AND WE DO THIS
WITH A COMBINATION OF GASES

AND GUNPOWDER.

THE GUNPOWDER EXPLODES,
SENDS A PISTON DOWN,

COMPRESSES HYDROGEN GAS
UP TO ABOUT 1 MILLION TIMES

THE ATMOSPHERIC PRESSURE
OF THE AIR WE BREATHE.

WHEN THAT HAPPENS,
AND IT'S LET LOOSE,

IT SENDS THE PROJECTILE DOWN
THIS TUBE INTO THE CHAMBER.

THAT'S WHEN WE SEE
THE MAGIC HAPPEN.

Narrator: PETER THINKS
THAT A SINGLE ASTEROID STRIKE

COULD'VE WEAKENED
ONE SIDE OF THE MOON,

MAKING IT MORE PRONE
TO VOLCANIC FLOODS,

BUT THE ASTEROID
WOULD'VE HAD TO BE HUGE,

HUNDREDS OF MILES ACROSS.

♪♪

PETER BELIEVES HE'S FOUND
EVIDENCE OF ONE ASTEROID STRIKE

BIG ENOUGH TO FIT THE BILL.

BUT THERE'S A PROBLEM --

IT'S ON THE WRONG SIDE
OF THE MOON.

♪♪

♪♪

Narrator: PLANETARY SCIENTIST
PETER SCHULTZ

IS HOPING TO SOLVE ONE OF
THE MOON'S GREATEST MYSTERIES.

WHAT LED TO THE DARK AREAS
OF LAVA

THAT COVER THE NEARSIDE
OF THE THE MOON,

AND WHY ARE THEY CONFINED
TO ONLY THAT SIDE?

THE ANSWER, HE BELIEVES,
IS TIED TO EVIDENCE

OF A GIANT ASTEROID STRIKE
FOUND ON THE OPPOSITE SIDE.

HERE'S THE MOON.
THIS IS THE NEARSIDE.

THIS IS THE SIDE THAT HAS ALL
THESE LAVA PLAINS COVERING IT,

VERY SMOOTH,
NOT VERY MANY CRATERS.

BUT THERE'S ONLY ONE BIG IMPACT
ON THE MOON THAT WE KNOW TODAY,

AND THAT'S ON THE OTHER SIDE,

AND THIS IS
THE SOUTH POLE-AITKEN BASIN,

ALMOST LARGER
THAN THE RADIUS OF THE MOON.

THE SOUTH POLE-AITKEN BASIN,
1,550 MILES WIDE

AND ALMOST 5 MILES DEEP.

IT IS THE LARGEST IMPACT CRATER
ON THE MOON

AND ONE OF THE LARGEST
IN THE SOLAR SYSTEM.

PETER WANTS TO INVESTIGATE
IF THE GIANT ASTEROID

THAT CREATED
THIS ENORMOUS CRATER

COULD ALSO CRITICALLY DAMAGE
THE MOON ON THE OPPOSITE SIDE.

♪♪

HE USES THE NASA AMES GUN
TO RECREATE THE BIRTH

OF THE MASSIVE
SOUTH POLE-AITKEN BASIN.

♪♪

HERE IS WHAT WE'RE GONNA HIT,

AND WE'RE GONNA HIT IT
WITH THIS TINY GLASS SPHERE.

WE'RE GOING TO PUT IT ON
JUST LIKE A GOLF TEE

AND SLAM IT
AT REALLY HIGH SPEEDS.

♪♪

THE TEAM LOADS THE GUN
WITH 100 GRAMS OF GUNPOWDER

AND PLACE
THE SURROGATE MOON IN POSITION.

♪♪

WITH THE GUN LOCKED AND LOADED,

A PUMP SUCKS AIR
OUT OF THE CHAMBER

TO RECREATE THE CONDITIONS
OF OUTDOOR SPACE,

AND IT'S READY TO FIRE.
-HERE WE GO.

[ BUZZING ]

♪♪

5.32 K.

VERY GOOD.

FOOTAGE FROM THE HIGH-SPEED
CAMERA REVEALS WHAT HAPPENED.

THE IMPACT TO THE BOTTOM OF
THE SPHERE CREATES A SHOCK WAVE

THAT TRAVELS RIGHT THROUGH
TO THE OTHER SIDE.

WHERE THE WAVE FRONTS CONVERGE,

THEY CRACK THE BODY
OF THE SPHERE.

SO HERE COMES THE PROJECTILE.

IT HITS RIGHT HERE,
AND THE SHOCK WAVE BEGINS,

AND THEN THE SHOCK WAVE
CONVERGES,

AND IT'S INSIDE THE SPHERE.

AND NOTHING IS ONE THE SURFACE
ON THE OPPOSITE SIDE.

IT'S ALL OF IT ON THE INSIDE,

AND THEN EVERYTHING
BEGINS TO FAIL,

AND IT GETS THIS CRACK
THAT COMES ALL THE WAY UP.

♪♪

PETER THINKS THAT THIS
SHOCK WAVE IS CRUCIAL...

HA!

IT EXPLAINS HOW A MASSIVE IMPACT
ON ONE SIDE OF THE THE MOON

COULD'VE CREATED DEEP CRACKS
ON THE OPPOSITE SIDE.

OOH. LOOK AT THAT.

THE SHOCK WAVES STARTED HERE,
PROPAGATED THROUGH,

AND CAUSED ALL THIS DAMAGE
THAT'S ON THE INSIDE,

BUT IT WENT FROM THE INSIDE-OUT

SO THAT WHEN YOU LOOK
AT THE BACKSIDE...

...YOU CAN SEE THIS WHOLE
PORTION JUST POPPED RIGHT OFF.

Narrator:
BUT THE SOUTH POLE-AITKEN IMPACT

ALONE CAN'T EXPLAIN

THE FULL STORY
OF THE MAN IN THE MOON,

BECAUSE IT TOOK ANOTHER
COSMIC EVENT

TO TURN THE CRACKS
INTO FLOODS OF LAVA.

FOUR POINT THREE BILLION
YEARS AGO,

A HUGE ASTEROID STRIKES
THE FAR SIDE OF THE MOON.

VIOLENT SHOCK WAVES TRAVEL
THROUGH THE MOON.

WHERE THE SHOCK WAVES CONVERGE,

THEY CAUSE THE INSIDE
OF THE MOON TO CRACK,

BUT THE MAN IN THE MOON
DOESN'T YET SHOW HIS FACE.

A FEW HUNDRED MILLION YEARS
LATER, ASTEROIDS RAIN DOWN,

PUNCTURING THE WEAKENED CRUST
AND RELEASING OCEANS OF LAVA.

AS THE LAVA COOLS,
IT SOLIDIFIES,

FINALLY TURNING
INTO THE DARK BASALT ROCK

THAT MAKES UP
THE MAN IN THE MOON.

COLLISIONS WITHIN
OUR SOLAR SYSTEM

ARE THE WAY
THAT WE HAVE A MOON AT ALL.

WE THINK THAT THE MOON
WAS FORMED BY A GIANT COLLISION

AND THAT, PERHAPS,
COLLISIONS ARE PART OF

HOW THE MOON
EVOLVES SUBSEQUENTLY.

WITHOUT COLLISIONS,
WE WOULDN'T HAVE A MOON

AND CERTAINLY NOT A MOON
THAT LOOKS THE WAY IT DOES.

SCIENTISTS SOLVE THE MYSTERY

OF WHY THE NEARSIDE OF THE MOON
LOOKS THE WAY IT DOES,

BUT WHAT ABOUT
THE SIDE OF THE MOON

THAT WE CAN'T SEE FROM EARTH?

♪♪

NEW EVIDENCE SUGGESTS
THAT THE FAR SIDE

MAY HIDE AN EVEN DARKER PAST.

FOR THE LONGEST TIME,
THE FAR SIDE OF THE MOON

WAS JUST A MATTER FOR SCI-FI.

WE HAD NO IDEA WHAT WAS ON
THE FAR SIDE OF THE MOON.

WE COULDN'T SEE IT,
AND SO, OF COURSE,

EVERYONE'S MIND
ALWAYS GOES TO ALIENS.

THAT'S CLEARLY
WHERE THEY WERE HIDING.

I THINK
THE FAR SIDE OF THE MOON

HAS ALWAYS HAD THIS WONDERFUL
POETIC ASPECT TO IT.

IT'S VERY INTRIGUING.

PEOPLE EVEN CALLED IT
THE DARK SIDE OF THE MOON,

AND IT TURNS OUT,
THERE WAS A MYSTERY

WAITING FOR US
THERE THE ENTIRE TIME.

Narrator: IS THIS SO-CALLED
DARK SIDE

THE SECRET BURIAL SITE

OF THE MOON'S
LONG-LOST SIBLING?

♪♪

♪♪

Narrator:
SCIENTISTS ARE EDGING CLOSER

TO REVEALING THE SECRET
HISTORY OF OUR MOON,

BUT PERHAPS THE BIGGEST
MYSTERY OF ALL

IS THE ONE THAT LIES
HIDDEN FROM EARTH,

THE FAR SIDE OF THE MOON.

THE FAR SIDE OF THE MOON
HAS ALWAYS BEEN INTRIGUING,

MOSTLY BECAUSE WE COULDN'T
SEE IT FROM THE EARTH.

Oluseyi: AN INTERESTING THING
ABOUT THE MOON

IS THAT IT ALWAYS KEEPS
THE SAME SIDE FACING THE EARTH,

AND THIS IS A NORMAL RESULT
OF CLOSE-ORBITING BODIES.

THE MOON IS TIDALLY LOCKED
TO THE EARTH,

AND THAT MEANS THAT AS IT
ROTATES AROUND OUR PLANET,

IT ALWAYS SHOWS THE SAME FACE
TOWARDS THE PLANET

AS IT GOES AROUND.

♪♪

Narrator: SCIENTISTS GET
THEIR FIRST GLIMPSE

OF THE FAR SIDE OF THE MOON
IN THE LATE 1950s.

ALTHOUGH THE AMERICANS LANDED
A HUMAN ON THE MOON FIRST,

IT WAS ACTUALLY THE SOVIETS
WHO WERE ABLE TO EXPLORE

THE MOON REALLY THOROUGHLY
BEFORE THE AMERICANS COULD.

THEY ACTUALLY SENT
A PROBE AROUND

TO THE FAR SIDE OF THE MOON,

THE SIDE WE CAN
NEVER SEE FROM EARTH,

AND DISCOVERED SOMETHING
REALLY WEIRD.

IN STARK CONTRAST TO
THE LOWLANDS OF THE NEARSIDE,

THE FAR SIDE IS DEEPLY CRATERED
AND MOUNTAINOUS.

IT'S AN ALIEN LANDSCAPE.

♪♪

DATA FROM NASA'S
MOON MISSION GRAIL

REVEALS SOMETHING
EVEN MORE MYSTERIOUS.

ON THE LOWLANDS OF THE NEARSIDE
OF THE MOON,

THE CRUST IS LITTLE MORE
THAN 15 MILES DEEP.

♪♪

BUT ON THE MOUNTAINOUS
FAR SIDE...

IT'S UP TO 2 1/2 TIMES
THICKER.

THAT MEANS THE THE MOON
IS LOPSIDED.

IT'S AN ASTONISHING REVELATION
THAT ONLY ADDS TO THE MYSTERY.

WHAT CREATED THE MOUNTAINOUS
FAR SIDE OF THE MOON

AND GAVE IT
ITS SUPERTHICK CRUST?

♪♪

[ WHIRRING ]

♪♪

ERIK ASPHAUG
IS A PLANETARY GEOLOGIST.

HE BELIEVES HE CAN SOLVE
THE MYSTERY.

HIS IDEA IS INSPIRED BY A COMET.

SO THIS HERE IS COMET 67P.

IT'S MOSTLY DIRT AND ICE
MIXED TOGETHER.

AND WHAT YOU CAN SEE

IS IT'S REALLY
TWO OBJECTS STUCK TOGETHER.

THERE'S THE NECK.

THERE'S THE HEAD.

THERE'S THE BODY.

THERE'S LAYERS
ALL OVER THIS OBJECT.

COMET 67P IS MADE
FROM TWO COMETS

THAT COLLIDED TO BECOME ONE.

IS IT POSSIBLE THAT THE MOON

IS ALSO AN AMALGAMATION
OF TWO DIFFERENT BODIES?

ERIK'S IDEA IS INCREDIBLE.

FOR TENS OF MILLIONS OF YEARS,

THE EARTH MAY HAVE HAD
TWO MOONS --

A LARGE MOON
AND A SMALLER TWIN SISTER.

ERIK THINKS THAT THIS
SMALLER MOON

COULD'VE MERGED WITH
ITS LARGER SIBLING

TO CREATE THE FAR SIDE
OF THE MOON'S THICK CRUST,

♪♪

BUT WHY DIDN'T
TWO MOONS COLLIDING

SMASH EACH OTHER TO PIECES?

♪♪

ERIK CARRIES OUT NUMERICAL
MODELING TO INVESTIGATE.

HE THINKS THE SPEED
ON THE COLLISION IS KEY.

IN THIS KIND OF COLLISION
THAT WE MODELED,

IT'S BASICALLY TWO OBJECTS
ORBITING THE EARTH

IN THE SAME ORBIT
FALLING INTO EACH OTHER,

SO THEY DON'T COME IN
WITH A LOT OF SPEED.

IT'S COMPLETELY DIFFERENT
PHYSICS,

AND THAT'S WHAT WE FOUND OUT
WITH OUR MODELING.

YOU CAN THINK OF IT ALMOST AS
A GARGANTUAN LANDSLIDE.

Narrator: ERIK THINKS
THAT THE TWO MOONS COLLIDE

AT AN INCREDIBLY SLOW SPEED,

ABOUT A TENTH OF THE SPEED
OF A TYPICAL ASTEROID COLLISION.

♪♪

INSTEAD OF BLASTING OUT
A CRATER,

THE SMALL SISTER MOON FLATTENS
OUT LIKE A COSMIC PANCAKE...

SPREADING ITSELF
ACROSS THE SURFACE

AND MAKING THE CRUST
MUCH THICKER.

IF THIS TWO-MOON THEORY
IS RIGHT,

THEN THE THICK CRUST
OF THE MOUNTAINOUS FAR SIDE

IS THE REMNANTS OF EARTH'S
LONG-LOST SECOND MOON.

♪♪

Plait: IF YOU HAD A TIME MACHINE
AND WENT BACK

TO 100 OR 50 MILLION YEARS
AFTER THE EARTH FORMED,

AND YOU LOOKED UP,

YOU WOULD SEE A BIG MOON
IN THE SKY AND A LITTLER MOON,

AND EVENTUALLY, THAT LITTLE MOON
WOULD SMASH INTO IT.

I CAN'T IMAGINE.

I CAN'T IMAGINE HOW AWESOME
THAT WOULD BE,

TO SEE THAT UP IN THE SKY.

♪♪

Thaller: WHEN YOU HEAR
THE WORD "COLLISION,"

YOU THINK OF SOMETHING
VERY VIOLENT AND DRAMATIC

AND OVER IN AN INSTANT.

AND INSTEAD, IF THERE
REALLY WAS A SMALLER MOON

COLLIDING SLOWLY WITH OUR MOON,

IT WAS MORE OF
A GRAVITATIONAL SNUGGLE-UP.

IT HAPPENED OVER
A LONG PERIOD OF TIME.

Narrator: SCIENTISTS ARE
BEGINNING TO SHED LIGHT

ON THE MANY MYSTERIES
OF THE MOON...

...EXPLAINING ITS VIOLENT BIRTH
AND ITS EQUALLY VIOLENT HISTORY.

AMAZINGLY, SOMETHING AS CLOSE
AND OBVIOUS AS THE MOON

IS ACTUALLY ONE OF
THE MOST MYSTERIOUS OBJECTS

IN THE ENTIRE UNIVERSE.

IT'S VERY RARE FOR ONE BIG IDEA
TO EXPLAIN EVERYTHING,

SO WE ADD MORE TO IT,
AND NOW WE HAVE

A MUCH MORE LAYERED
AND NUANCED UNDERSTANDING

OF HOW THE MOON FORMED,

BUT THERE ARE STILL
SOME WEIRD THINGS ABOUT THE MOON

THAT WE HAVE TO EXPLAIN.

♪♪

Narrator: BORN WHEN A PLANET
THE SIZE OF MARS

CRASHES INTO EARTH,

A SECOND COMPANION MOON
SLAMS INTO ITS SURFACE

TO CREATE
THE MOUNTAINOUS FAR SIDE...

♪♪

...AND A MASSIVE
ASTEROID COLLISION

MARKS THE BEGINNING OF WHAT
BECOMES THE MAN IN THE MOON.

♪♪

THE MOON MAY HAVE ONE OF
THE MOST EXCITING STORIES

IN THE UNIVERSE.

♪♪

♪♪