Space's Deepest Secrets (2016–…): Season 5, Episode 2 - Space's Deepest Secrets - full transcript

A mysterious star hundreds of light years away might hold the hard evidence of extraterrestrial life, as experts speculate that its bizarre behavior points to proof of a massive alien-made megastructure.

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Narrator:
IN A SKY FULL OF STARS,

ONE DEEPLY MYSTERIOUS LIGHT

HAS SET THE WORLD
OF ASTRONOMY ON FIRE.

STARS SIMPLY DO NOT
BEHAVE LIKE THIS.

Narrator: THIS STRANGE STAR
IS DIMMING ERRATICALLY.

IT LOOKS LIKE SOMETHING COLOSSAL
BLOCKS ITS LIGHT, BUT WHAT?

IT'S DIMMING IN A WAY THAT
SEEMED ABSOLUTELY IMPOSSIBLE.

WHAT THE HECK IS GOING ON?

Narrator: SCIENTISTS SCRAMBLE
TO IDENTIFY THE CULPRIT.

COULD IT BE
A VAST SWARM OF COMETS,

THE FALLOUT FROM
A PLANETARY SMASHUP,



OR SOMETHING EVEN STRANGER?

Plait: IT'S POSSIBLE
THAT AN ALIEN CIVILIZATION

WOULD LOOK A LOT
LIKE WHAT WE'RE SEEING.

Narrator: SCIENTISTS HAVE LONG
PREDICTED AN ADVANCED ALIEN RACE

MIGHT REVEAL ITSELF BY BLOCKING
THE LIGHT FROM ITS PARENT STAR.

IS WHAT WE'RE SEEING
AN ALIEN MEGASTRUCTURE?

YOU SHOULD NOT THROW AWAY IDEAS
BECAUSE THEY SEEM FARFETCHED.

THEY MIGHT BE RIGHT.

Narrator:
THIS IS THE INSIDE STORY

OF ONE OF THE GREATEST PUZZLES
IN MODERN ASTRONOMY...

THIS IS WHY I DO WHAT I DO.
IT'S A BLAST.

Narrator: ...THE RACE
TO UNLOCK THE SECRETS

OF THE ALIEN MEGASTRUCTURE.

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS



♪♪

ASTRONOMERS AROUND THE WORLD
ARE LOCKED IN A RACE

TO SOLVE ONE OF THE GREATEST
MYSTERIES OF THE 21st CENTURY.

THEY HAVE DISCOVERED
AN EXTREMELY STRANGE STAR.

THEY CALL IT TABBY'S STAR.

♪♪

TABBY'S STAR APPEARS TO HAVE

SOMETHING ENORMOUS
IN ORBIT AROUND IT.

FROM TIME TO TIME, THIS OBJECT
PASSES IN FRONT OF THE STAR

AND CAUSES ITS LIGHT TO DIP.

YOU HAVE TO UNDERSTAND, WE SEE
MILLIONS OF STARS IN THE SKY.

TABBY'S STAR IS THE ONLY STAR

OUT OF ALL OF THESE
THAT WE'VE SEEN THIS HAPPEN.

Tremblay:
ALL STARS VARY TO SOME DEGREE,

BUT NO STARS VARY
AS SHARPLY OR AS RAPIDLY

OR AS IRREGULARLY
AS TABBY'S STAR DOES.

Narrator: WHAT COULD BE BLOCKING
THE LIGHT FROM TABBY'S STAR?

ONE THEORY STANDS OUT.

IS THE STAR BEING GRADUALLY
ENCASED BY AN ALIEN CIVILIZATION

WITH A THIRST
FOR LARGE-SCALE CONSTRUCTION?

I CANNOT OVERSTATE WHAT KIND
OF SCALES WOULD BE INVOLVED

IN CREATING AN OBJECT
THAT COULD ENCOMPASS A STAR.

IT'S JUST REALLY,
REALLY HARD TO IMAGINE.

♪♪

Narrator: SO WHAT'S GOT
REPUTABLE SCIENTISTS

TALKING ABOUT ALIEN
MEGASTRUCTURES?

THE STORY BEGINS WITH A SIMPLE,

BUT BAFFLING, OBSERVATION MADE
BY ASTRONOMER TABBY BOYAJIAN.

TABBY IS THE FIRST SCIENTIST

TO DISCOVER THE BIZARRE
BEHAVIOR OF THIS STAR.

PREVIOUSLY, IT WENT BY
THE CATCHY NAME

OF KIC846-2852.

THIS IS AN IMAGE
SHOWING THE STARS

AROUND KIC846-2852.

AND IF WE ZOOM IN TO THE CENTER
HERE, THIS IS THE STAR --

THE MOST MYSTERIOUS STAR
IN THE GALAXY.

TABBY USES NASA'S
KEPLER TELESCOPE

TO STUDY THE STAR
THAT NOW BEARS HER NAME.

THIS INNOVATIVE TELESCOPE
IS BUILT TO DETECT

THE FAINT SHADOW
OF DISTANT WORLDS

AS THEY PASS IN FRONT
OF THEIR HOME STARS.

THE IDEA BEHIND
THE KEPLER MISSION IS SO ELEGANT

BECAUSE IT'S SO SIMPLE.

YOU TAKE AN AREA OF THE SKY,

AND YOU JUST STARE AT IT
FOR YEARS.

WHEN YOU SEE THIS SMALL PLANET
GOING ACROSS ITS STAR,

THE LIGHT DIMS,
BUT IN A REGULAR PATTERN,

AGAIN AND AGAIN AND AGAIN,

AND THEN YOU KNOW
YOU'VE FOUND A PLANET.

Narrator: IN JUST NINE YEARS,

THE KEPLER MISSION DISCOVERS
OVER 2,000 NEW WORLDS.

MOST PLANETS BLOCK OUT LESS THAN
1% OF THEIR PARENT STAR'S LIGHT.

BUT WHEN THE TELESCOPE
LOOKS AT TABBY'S STAR,

IT SEEMS DIPS IN BRIGHTNESS
ON ANOTHER SCALE.

♪♪

MOST OF THE TIME, THE STAR
IS AT NORMAL BRIGHTNESS.

BUT THEN ABOUT TWO YEARS
INTO THE KEPLER MISSION

IS THE FIRST REALLY BIG DROP
WE SAW, WHICH IS LIKE 15%.

A DROP IN BRIGHTNESS OF 15%
IS ENORMOUS.

BUT TWO YEARS LATER,

THE TEAM CAPTURES SOMETHING
EVEN MORE ASTONISHING.

OVER HERE ON THE FAR RIGHT,

YOU CAN SEE WE HAVE THIS
HUGE COMPLEX OF DIPS.

THE STAR GOES NUTS HERE.

THE BRIGHTNESS IS FLUCTUATING
IN MANIC WAYS.

THE DEEPEST ONE HERE
GOES TO OVER 20%,

AND THIS IS HUGE.

WE'VE NEVER SEEN
ANYTHING ELSE LIKE IT.

Narrator:
THE DIPS DON'T LAST LONG.

EACH EVENT SPANS
JUST A FEW DAYS,

BUT THE DROPS IN LIGHT
ARE ENORMOUS.

WHAT CAUSES THIS STAR

TO ERRATICALLY DIP BY OVER 20%?

♪♪

AS THE SUN RISES
OVER MT. WILSON OBSERVATORY,

TABBY CAN USE
THE SOLAR TELESCOPE

TO SHOW US WHY SUCH DEEP DIPS

IN THE STAR'S BRIGHTNESS
ARE SO UNUSUAL.

BECAUSE WITH THIS TELESCOPE,

SHE CAN DEMONSTRATE JUST HOW BIG
AN OBJECT WOULD HAVE TO BE

TO CREATE SUCH ENORMOUS DIPS
IN LIGHT.

ROLL MY SLEEVES UP.
WE'RE GONNA CONTROL THE SUN.

HERE WE GO.

THE TELESCOPE
ABOVE TABBY'S HEAD

PROJECTS A LIVE IMAGE
OF THE SUN.

IF THIS PROJECTED IMAGE
WERE TABBY'S STAR,

WHAT PERCENTAGE
OF THE STAR'S LIGHT

WOULD THE PLANETS
WE'RE FAMILIAR WITH BLOCK OUT?

SO IF YOU HAD
AN EARTH-LIKE PLANET,

IT WOULD LOOK
SOMETHING LIKE THIS.

THIS IS A BALL BEARING HERE,
AND IT IS BLOCKING OUT

A VERY TINY FRACTION
OF THE STAR'S LIGHT.

THE EARTH MAY SEEM BIG TO US,

BUT COMPARED TO A STAR,
IT'S TINY.

IT WOULD BLOCK OUT JUST
0.01% OF TABBY'S STAR'S LIGHT.

♪♪

WHAT ABOUT THE BIGGEST PLANET
IN OUR SOLAR SYSTEM?

HOW MUCH STARLIGHT
WOULD JUPITER BLOCK?

IN THE CASE OF
A JUPITER-SIZED PLANET,

WE WOULD HAVE SOMETHING
THE SIZE OF THIS COIN

THAT'S PASSING IN FRONT OF
THE STAR,

BLOCKING OUT ABOUT 0.5%
OF THE STAR'S LIGHT ITSELF,

WHICH IS STILL
A PRETTY SMALL FRACTION

OF THE OVERALL LIGHT
OUTPUT OF THE STAR.

EVEN ENORMOUS JUPITER
IS TOO SMALL

TO ACCOUNT FOR TABBY'S STAR'S
DROPS IN BRIGHTNESS.

♪♪

SO HOW BIG WOULD AN OBJECT
HAVE TO BE?

SO YOU WOULD HAVE SOMETHING
ALONG THE SIZE OF THIS.

AND THIS IS BLOCKING
A HUGE AMOUNT OF LIGHT.

WE'RE TALKING UP TO 22%.

IF THIS WERE A PLANET, IT WOULD
BE ALMOST 373,000 MILES ACROSS.

A WORLD ALMOST 100 TIMES BIGGER
THAN JUPITER.

THAT WOULD MAKE IT THE LARGEST
PLANET EVER DISCOVERED.

BUT FOR PHYSICISTS,
THAT'S A PROBLEM.

IT TURNS OUT IT'S IMPOSSIBLE
FOR A PLANET TO GROW THIS BIG.

THE BIGGEST PLANET YOU CAN GET
IS ROUGHLY JUPITER-SIZED.

IF YOU START ADDING MORE MASS
TO JUPITER, IT WON'T GET BIGGER.

IT'LL GET DENSER.

A DIP IN THE STAR'S BRIGHTNESS
OF 22% IS JUST TOO BIG

TO BE CAUSED BY A PLANET.

Narrator: SCIENTISTS KNOW
THAT SOMETHING IS BLOCKING OUT

THE LIGHT FROM TABBY'S STAR.

IF NOT A PLANET, WHAT IS IT?

THE RACE TO FIND ANSWERS IS ON.

WITH NO OBVIOUS NATURAL SUSPECT,

SOME ASTRONOMERS
BEGIN TO INVESTIGATE

UNNATURAL EXPLANATIONS.

THE BEHAVIOR OF TABBY'S STAR
WAS SO WEIRD,

AND WE HAD NO IDEA
WHAT WAS GOING ON

THAT WE WERE WILLING
TO ENTERTAIN ALMOST ANYTHING,

INCLUDING ALIENS.

Oluyesi: THERE'S A SECRET
IN THE SCIENTIFIC COMMUNITY.

EVEN THOUGH WE CAN'T SAY OUT
LOUD THAT WE BELIEVE IN ALIENS,

I THINK WE ALL HAVE A SENSE THAT
MAYBE THERE IS LIFE OUT THERE.

Narrator: BUT WHY WOULD AN ALIEN
RACE WANT TO BUILD A STRUCTURE

BIG ENOUGH TO BLOCK OUT MORE
THAN 20% OF THEIR STAR'S LIGHT?

♪♪

A CLUE LIES
IN THE HEART OF NEVADA.

SPREAD OUT OVER TWO SQUARE MILES
OF DESERT

STAND 10,000 REFLECTIVE PANELS.

EACH BOWS TO WORSHIP THE SUN.

♪♪

♪♪

STEVE CROFT IS AN ALIEN HUNTER.

SCIENTISTS LOVE
A GOOD HEAD SCRATCHER,

AND TABBY'S STAR IS REALLY
ONE OF THE BIGGEST MYSTERIES

TO COME ALONG IN ASTRONOMY
IN THE LAST FEW YEARS.

Narrator: STEVE BELIEVES
THAT THIS SOLAR FACILITY

MIGHT BE A MINIATURE VERSION
OF THE MEGASTRUCTURE

THAT COULD BE
BLOCKING TABBY'S STAR.

COULD ADVANCED ALIENS HAVE BUILT
A MONSTROUS SOLAR FARM

AROUND THE STAR
TO HARVEST ENERGY FROM IT?

♪♪

♪♪

♪♪

♪♪

Narrator: TABBY'S STAR, THE
STRANGEST STAR IN THE GALAXY,

HAS ASTRONOMERS STUMPED.

ITS BRIGHTNESS DIPS ERRATICALLY.

COULD A COLOSSAL ALIEN
MEGASTRUCTURE

BE BLOCKING OUT
THE STAR'S LIGHT?

AT A SOLAR FACILITY IN THE HEART
OF A NEVADA DESERT,

ASTRONOMER STEVE CROFT
BELIEVES THE ANSWER IS YES.

RIGHT BEHIND ME
IS A HUGE NUCLEAR REACTOR

THAT'S IN THE CENTER
OF OUR SOLAR SYSTEM

THAT'S BEEN HERE
FOR BILLIONS OF YEARS

AND WILL CONTINUE TO BE HERE
FOR BILLIONS OF YEARS,

JUST PUTTING OUT
VAST AMOUNTS OF ENERGY.

AND SO THAT ENERGY REALLY
IS COMING FOR FREE,

AND ALL WE HAVE TO DO
IS CAPTURE IT.

THIS SOLAR POWER PLANT
CAN POWER 75,000 HOMES,

BUT STEVE THINKS
THIS IS SMALL FRY

COMPARED TO WHAT ALIENS
MIGHT BUILD

BECAUSE THEIR ENERGY NEEDS
WILL FAR OUTSTRIP OUR OWN.

I THINK ALIEN TECHNOLOGY MAY BE
AS FAR BEYOND OUR IMAGINATION

AS THE TECHNOLOGY THAT WE HAVE
TODAY IS BEYOND THE IMAGINATION

OF PEOPLE A COUPLE
OF HUNDRED YEARS AGO.

IF YOU'RE TRAVELING BETWEEN
THE STARS,

IF YOU'RE BUILDING
HUGE STRUCTURES IN SPACE,

IF YOU'RE POWERING
SOME TECHNOLOGY

THAT IS BEYOND
OUR WILDEST IMAGININGS,

THE POWER REQUIREMENTS
FOR THESE THINGS MAY BE HUGE.

AND THIS TREMENDOUS THIRST
FOR ENERGY

MAY MEAN THAT PLANET-BASED
POWER PLANTS JUST DON'T CUT IT.

AS ENERGY NEEDS INCREASE,

YOU COULD BUILD MORE AND MORE
SOLAR FARMS LIKE THIS

UNTIL YOU'VE COVERED THE WHOLE
SURFACE OF YOUR PLANET.

WHAT DO YOU DO THEN?

YOU'RE GONNA HAVE TO GO
INTO SPACE.

Narrator: AWAY FROM THE CONFINES
OF A PLANET,

AN ALIEN SOLAR FARM
COULD GROW HUGE.

SO BIG IT COULD HARVEST
ALMOST ALL THE ENERGY

FROM THE STAR IT SURROUNDS.

IT WOULD TAKE THOUSANDS OF
GIGANTIC SOLAR PANEL ARRAYS,

EACH OVER 600,000 MILES WIDE,

TO FORM A SPHERE OF SOLAR PANELS
AROUND THE STAR.

AND AS THIS ENORMOUS STRUCTURE
MOVES,

IT BLOCKS OUT THE STAR'S LIGHT.

COULD THIS BE THE CAUSE OF THE
MYSTERIOUS DIPS OF TABBY'S STAR?

♪♪

AN ENGINEERING FEAT LIKE THIS
COULD REALLY ONLY BE DESCRIBED

BY ONE WORD --
A MEGASTRUCTURE.

IT MIGHT SEEM CRAZY TO US
IMAGINE THESE MEGASTRUCTURES,

BUT THIS MIGHT BE ROUTINE
FOR ALIENS

TO BE BUILDING THINGS LIKE THIS.

Narrator:
IF THIS THEORY IS RIGHT,

TABBY'S STAR
IS THE BIGGEST DISCOVERY

IN THE HISTORY OF SCIENCE.

BEFORE SCIENTISTS CAN CONCLUDE
IT'S ALIENS,

THEY MUST RULE OUT
ALL OTHER OPTIONS.

IS A GIANT SWARM OF COMETS
THE TRUE CULPRIT?

WE NEED SOMETHING VERY LARGE
TO BLOCK THE STARLIGHT

THAT WE SEE COMING
FROM TABBY'S STAR.

COMETS ARE VERY SMALL,
BUT WAIT A SEC --

WHEN THEY WARM UP, A CLOUD
OF GAS EXPANDS AROUND THEM

AND CAN GET LARGER THAN PLANETS.

COMETS ARE DIRTY SNOWBALLS
MADE FROM ICE AND ROCK.

THEY NORMALLY SPEND
THEIR ENTIRE EXISTENCE

FAR FROM THE HEART OF THE SUN.

BUT WHEN THEY'RE KICKED
INTO ORBIT

TO BRING THEM CLOSE
TO THEIR PARENT STAR,

DUST AND GAS EVAPORATE
OUT OF THE COMET'S CORE,

CREATING AN ENORMOUS TAIL.

BUT TABBY'S STAR IS DIMMING
BY AS MUCH AS 22%.

EVEN WITH A HUGE TAIL,

A SINGLE COMET COULDN'T
BLOCK OUT THAT MUCH LIGHT.

Boyajian:
ONE COMET IS NOT ENOUGH.

YOU NEED HUNDREDS OR THOUSANDS
TO REPRODUCE

WHAT WE SEE
IN THE DATA FOR THIS STAR.

Narrator: WE'VE OBSERVED MANY
COMETS IN OUR OWN SOLAR SYSTEM,

BUT WE'VE NEVER SEEN HUNDREDS
OF COMETS CLUSTERED TOGETHER,

TRAVELING LIKE A SWARM.

THEY'RE NOT PACK ANIMALS,
AND SO IT WOULD BE UNUSUAL

TO SEE A LARGE AMOUNT OF COMETS
IN ONE PLACE.

Narrator: WHAT COULD CREATE
A SWARM OF COMETS?

SCIENTISTS HAVE ONE IDEA,

BUT IT WOULD REQUIRE
A VERY SPECIAL STAR SYSTEM.

COULD TABBY'S STAR BE NOT ONE,
BUT TWO STARS?

♪♪

Tremblay: TABBY'S STAR SEEMS
REALLY STRANGE,

BUT ONE SIMPLE WAY
TO EXPLAIN ITS BEHAVIOR

WOULD BE BY ADDING
ANOTHER STAR TO THAT SYSTEM.

A DOUBLE STAR SYSTEM
COULD DEFINITELY CAUSE

REALLY WEIRD THINGS TO HAPPEN
TO THE ORBIT OF BODIES

AROUND THOSE TWO STARS.

IF A SECOND STAR IS ORBITING
AROUND TABBY'S STAR,

IT COULD ACT LIKE
A COSMIC WRECKING BALL.

ITS GRAVITY WOULD PULL WHOLE
GROUPS OF COMETS OUT OF ORBIT

AND SEND THEM HURTLING INWARDS.

AS THEY GET CLOSE TO TABBY'S
STAR,

THEY HEAT UP AND GROW TAILS
OF GAS AND DUST

MORE THAN 6 MILLION MILES LONG.

A 500-STRONG SWARM
OF ICY MISSILES

PASSES OVER THE FACE
OF THEIR STAR.

THEIR DUST OBSCURING
TABBY'S STAR FOR DAYS AT A TIME.

IF THIS IDEA IS TRUE
THAT ANOTHER STAR

PASSED NEAR TABBY'S STAR AND
SENT THIS SWARM DEBRIS INWARDS,

THEN THERE IS GONNA BE EVIDENCE
OF THIS STAR'S EXISTENCE.

Narrator: THE RACE IS ON
TO FIND THIS EVIDENCE,

AND WITH A SPECIAL
INFRARED CAMERA,

ONE ASTRONOMER IS ABOUT TO MAKE
AN INTRIGUING DISCOVERY.

♪♪

♪♪

♪♪

Narrator: AT LOWELL OBSERVATORY
IN ARIZONA,

DAN CLEMENS WANTS TO KNOW
IF THERE REALLY IS A SECOND STAR

ORBITING AROUND TABBY'S STAR.

IF THE ANSWER IS YES,
IT COULD HELP EXPLAIN

WHY THE LIGHT FROM TABBY'S STAR
DIMS SO DRAMATICALLY.

Clemens: IT'S A PUZZLE.

HAVING A CHANCE
TO CRACK AWAY AT SOMETHING

THAT'S NEW AND UNUSUAL
KEEPS EVERY DAY FRESH.

♪♪

♪♪

Narrator: TONIGHT,
DAN WILL POINT HIS TELESCOPE

AT TABBY'S STAR.

ALL RIGHT, WE'RE GONNA MOVE.
EVERYBODY READY?

HE AND THE TEAM ATTACH
A SPECIAL INFRARED CAMERA.

THIS IS THE HAIRY PART.

IT'S THE DIFFERENCE BETWEEN
THEORY AND OBSERVATION, YEAH.

HOW MUCH WEIGHTLIFTING
YOU HAVE TO DO.

[ LAUGHS ]

DAN WILL USE THIS CAMERA
TO INVESTIGATE

IF TABBY'S STAR HAS A FAINTER
STAR ORBITING AROUND IT.

YEAH, WE NEED
TO DO A TWIST.

♪♪

GOOD.

-IS IT ON?
-IT'S ON.

PUTTING IN THE COORDINATES
OF TABBY'S STAR

SO THE TELESCOPE CAN KNOW
WHERE TO GO TO.

♪♪

♪♪

AND THAT KIND OF LOOKS
LIKE THE FIELD.

THERE, I THINK.

THIS IS TABBY'S STAR.

SO THIS IS AS LIVE
AS YOU GET.

THOSE ARE FRESHLY
HARVESTED PHOTONS.

EARLY RESULTS HAVE SHOWN
SOMETHING ASTONISHING.

THERE DOES SEEM TO BE
A SECOND STAR,

BUT IT'S SO FAINT
THAT ON THIS TELESCOPE,

IT'S ONLY VISIBLE AS A SMALL
BULGE IN TABBY'S STAR'S LIGHT.

THERE'S A LITTLE BIT OF
A BULGE OFF TO THE LEFT HERE

DUE TO THE FAINT COMPANION
TO TABBY'S STAR.

TABBY'S STAR IS TOO FAINT
TO SEE WITH YOUR NAKED EYE.

THE COMPANION STAR IS
GONNA BE 500 TIMES FAINTER.

WHEN SCIENTISTS USE
LARGER INSTRUMENTS

TO OBSERVE TABBY'S STAR,
THE EVIDENCE IS CLEAR.

THERE IS, INDEED, A SECOND STAR.

IF THIS STAR IS ORBITING
AROUND TABBY'S STAR,

IT COULD HAVE CREATED
A HUGE SWARM OF COMETS

THAT NOW ORBIT THE STAR
AND BLOCK ITS LIGHT.

♪♪

SO, IS IT CASE CLOSED?

NOT QUITE.

BECAUSE THROUGH A TELESCOPE,
LOOKS CAN BE DECEIVING.

THESE TWO STARS MAY NOT BE
AS CLOSE TO EACH OTHER

AS THEY FIRST APPEAR.

THE SKY IS JUST
A TWO-DIMENSIONAL PROJECTION

OF A VERY
THREE-DIMENSIONAL SPACE.

SO IT DOESN'T MEAN MUCH
IF TABBY'S STAR HAPPENS

TO BE NEXT TO ANOTHER STAR
IN THE SKY

UNLESS YOU KNOW THE DISTANCES
TO THOSE TWO STARS.

THEY COULD HAVE NOTHING TO DO
WITH EACH OTHER IF TABBY'S STAR

IS JUST IN FRONT OF IT
ALONG THE LINE OF SIGHT.

Clemens: THE REAL DEFINITIVE
TEST IS HOW IS THIS STAR MOVING

COMPARED TO TABBY'S STAR?

IS IT IN ORBIT OR NOT?

Narrator: DAN IS TRYING TO
CONFIRM WHETHER THIS SECOND STAR

REALLY IS IN ORBIT
AROUND TABBY'S STAR

OR JUST AN INTERLOPER PASSING
THROUGH THE SAME LINE OF SIGHT.

AND UNTIL WE KNOW IF THE TWO
STARS ARE CONNECTED,

WE CAN'T KNOW WHETHER THIS
SECOND STAR IS ULTIMATELY

RESPONSIBLE FOR BLOCKING OUT
TABBY'S STAR'S LIGHT.

♪♪

ASTRONOMERS NEED ANOTHER
APPROACH TO CRACK THIS MYSTERY.

AND FRESH THEORIES
NEED FRESH DATA.

SCIENTISTS AT
HARVARD COLLEGE OBSERVATORY

INVESTIGATE THE STAR'S BEHAVIOR
OVER THE LAST CENTURY.

JOSH GRINDLAY CAN DELVE DEEP

INTO THE HISTORY
OF TABBY'S STAR.

THAT'S BECAUSE THIS COLLECTION
HOLDS CLUES

TO TABBY'S STAR'S
HISTORIC BEHAVIOR.

SO DO YOU KNOW
WHERE IT WOULD BE?

IT'S SOMEWHERES IN HERE.

IF IT'S HISTORIC, THIS WOULD
BE THE EARLIEST PLATE,

SO I WOULD START UP THERE
AND THEN WORK YOUR WAY DOWN.

OKAY.

Narrator:
JOSH USES THESE PLATES

TO EXAMINE HOW TABBY'S STAR'S
LIGHT HAS CHANGED

OVER THE PAST 100 YEARS.

SCIENTISTS AT HARVARD
HAVE BEEN CAREFULLY ARCHIVING

IMAGES OF SPACE FOR WELL OVER
A CENTURY.

WE'VE GOT 106 YEARS
OF PLATES HERE.

OVER HALF A MILLION --
1886 TO 1992.

Narrator: THESE RECORDS
REVEAL THAT ASTRONOMERS

WERE OBSERVING TABBY'S STAR
LONG BEFORE ANYBODY REALIZED

THAT THERE WAS ANYTHING
UNUSUAL ABOUT IT.

TABBY'S STAR HAS BEEN IMAGED
ON THESE PLATES

ABOUT 2,700 TIMES.

AND THESE OLD PLATES
CONTAIN A SECRET --

THE STAR'S RECENT FLICKERING
IS JUST HALF THE STORY.

Grindlay: SO HERE IS
A RELATIVELY EARLY PLATE

FROM THE HARVARD COLLECTION
TAKEN ON NOVEMBER 26, 1890.

THESE ARE PHOTO NEGATIVE PLATES.

STARS ARE BLACK. SKY IS WHITE.

AND IF I COMPARE THIS TO A PLATE

TAKEN AUGUST 24, 1989,

100 YEARS OF HISTORY

OF TABBY'S STAR
RIGHT IN FRONT OF US.

♪♪

JOSH IS ONE OF THE FEW PEOPLE
ON THE PLANET

ABLE TO DECIPHER THE SECRETS
WITHIN THESE PLATES.

Grindlay: SO I FIRST HAVE TO GO
IN HERE TO MY 1890 PLATE,

FIND TABBY'S STAR.

Narrator: HAS TABBY'S STAR
CHANGED OVER THE YEARS?

JOSH MEASURES THE DIAMETER
OF THE STAR

TO WORK OUT ITS BRIGHTNESS.

Grindlay: WHEN YOU MAGNIFY THEM

AND LOOK AT THEM IN DETAIL,
IT'S AN INCREDIBLE SIGHT.

Narrator: BY ANALYZING THESE
AND OVER 1,000 OTHER PLATES

OF TABBY'S STAR, SOMETHING
EXTRAORDINARY IS REVEALED.

Grindlay:
WHEN I LOOK OVER HERE

AT THE VERY END
OF THE HARVARD PLATE TAKING

AND FIND TABBY'S STAR
AND DO THE SAME THING,

COMPARED TO THE PLATE
THAT I JUST LOOKED AT FROM 1890,

TABBY'S STAR
IS ABOUT 10% FAINTER.

♪♪

Narrator:
IT'S AN ASTOUNDING REVELATION.

NOT ONLY IS TABBY'S STAR HOME
TO AN ENORMOUS MYSTERY OBJECT,

IT'S ALSO DOING SOMETHING
RARELY SEEN BEFORE IN A STAR.

IT'S SLOWLY LOSING
ITS BRIGHTNESS.

ONE THING WE TYPICALLY DON'T SEE
IS A STAR DIMMING

OVER MANY YEARS AND DECADES.

Thaller:
THERE WASN'T JUST ONE MYSTERY.

NOW THERE WERE TWO, AND THAT'S
EXACTLY WHAT SCIENTISTS LIKE.

Narrator: WHAT COULD EXPLAIN
BOTH STRANGE BEHAVIORS?

DOES IT POINT TO A DRAMATIC AND
VIOLENT PAST FOR TABBY'S STAR?

OR WILL ALIEN HUNTERS FINALLY
HAVE THE PROOF THEY NEED

TO CONFIRM THAT
WE'RE NOT ALONE IN THE UNIVERSE?

♪♪

♪♪

♪♪

♪♪

Narrator:
SCIENTISTS AROUND THE WORLD

RACE TO UNLOCK THE MYSTERIES
OF TABBY'S STAR.

AT FIRST, ASTRONOMERS THOUGHT
ITS LIGHT WAS JUST DIPPING

ERRATICALLY -- APPARENTLY BEING
BLOCKED BY AN UNKNOWN OBJECT.

BUT A NEW DISCOVERY
HAS THROWN A CURVEBALL.

IT SEEMS THE STAR

WAS ALSO SUBSTANTIALLY
BRIGHTER 100 YEARS AGO.

♪♪

WE BELIEVE THAT IT IS LIKELY

THAT THE TWO STRANGE BEHAVIORS
ARE CONNECTED.

IF YOU HAVE TWO VERY STRANGE
THINGS GOING ON,

IT'S MOST LIKELY DUE
TO ONE CAUSE,

NOT TWO COMPLETELY CRAZY THINGS.

COULD A VAST ALIEN MEGASTRUCTURE
BE ORBITING THE STAR?

♪♪

THIS IDEA EXPLAINS THE SHORT
DURATION DIPS IN BRIGHTNESS.

AS THE MEGASTRUCTURE SPINS,

IT PERIODICALLY ECLIPSES
THE STAR'S LIGHT.

BUT COULD THE NEWLY DISCOVERED,
CENTURY-LONG DIMMING

OF TABBY'S STAR ALSO ADD FUEL
TO THIS ALIEN ARGUMENT?

THE SECOND MYSTERY
ALLOWED OUR IMAGINATIONS

TO RUN A LITTLE BIT WILD.

WAS IT POSSIBLE WE HAD EVIDENCE
THAT OVER MANY, MANY DECADES,

THESE ALIENS HAD BEEN BUILDING
UP THIS SUPER STRUCTURE?

Narrator: AN ALIEN MEGASTRUCTURE
WOULD TAKE TIME TO CONSTRUCT.

♪♪

OVER 100 YEARS AGO,

ALIEN ENGINEERS START
WITH A SINGLE SOLAR PANEL,

BUT THE BUILDING'S
ONLY JUST BEGUN.

THEY ADD MORE AND MORE PANELS
UNTIL THE STRUCTURE

IS AS BIG AS THE EARTH.

NOW IT BLOCKS OUT PERHAPS
0.01% OF THE STAR'S LIGHT.

♪♪

AND THIS ENERGY-HUNGRY
SUPER CIVILIZATION

ISN'T GOING TO STOP.

SHELL BY SHELL,

THE MEGASTRUCTURE GROWS
AROUND THE STAR.

AND OVER THE COURSE
OF 100 YEARS,

THE STAR APPEARS
TO GRADUALLY DIM.

♪♪

BUT EXTRAORDINARY CLAIMS
REQUIRE EXTRAORDINARY EVIDENCE,

AND SCIENTISTS AROUND THE WORLD

ARE HUNTING FOR
A NATURAL EXPLANATION

BEFORE BLAMING E.T.

ALIENS ARE ALWAYS
THE LAST-RESORT HYPOTHESIS.

Narrator: SO, COULD THERE BE
A NATURAL EXPLANATION

FOR BOTH STRANGE BEHAVIORS?

IN BOSTON, MASSACHUSETTS,

NICK STONE THINKS HE MIGHT
HAVE CRACKED THE CASE.

Stone: I THINK
THAT THE LONG-TERM DIMMING

WE'VE OBSERVED IN TABBY'S STAR

IS THE SIGNATURE
OF A VIOLENT PAST.

♪♪

WE THINK THAT TABBY'S STAR

WAS IMPACTED
BY ONE OF ITS FORMER PLANETS

YEARS, DECADES, MAYBE CENTURIES
OR MILLENNIA AGO.

Narrator:
PLANETS ON UNSTABLE ORBITS

CAN SOMETIMES COLLIDE
WITH THEIR OWN STARS.

TO WATCH A PLANET CRASH
INTO A STAR

WOULD BE A PROFOUNDLY DRAMATIC
EVENT TO WITNESS,

AND WE MIGHT ACTUALLY BE DOING
THAT WITH TABBY'S STAR,

JUST VERY FAR AWAY.

THE STAR'S RESPONSE
WOULD BE DRAMATIC.

IT WOULD RAPIDLY BRIGHTEN
AND BECOME MUCH HOTTER.

THE BIGGER THE PLANET, THE MORE
ENERGY YOU PUMP INTO THE STAR,

AND THE MORE VIOLENT THE CHANGE
IN THE STAR'S POWER OUTPUT IS.

Narrator:
IF NICK'S RIGHT, MANY YEARS AGO,

A GAS GIANT AS BIG AS JUPITER
SMASHES INTO TABBY'S STAR.

♪♪

THE PLANET DISAPPEARS INTO
THE MASS OF BOILING PLASMA.

♪♪

ITS OUTER LAYERS STRIP AWAY

UNTIL ONLY THE CORE REMAINS.

THE FRICTION OF THE PLANET'S
CORE SUPERCHARGES TABBY'S STAR.

IT TURNS BLUE-WHITE
WITH INTENSE HEAT

AND FLARES UP
TO 100 TIMES BRIGHTER.

BUT THE STAR'S NEWFOUND
BRILLIANCE IS FLEETING.

♪♪

TABBY'S STAR WOULD EVENTUALLY
SETTLE DOWN

AND RETURN
TO ITS NORMAL STATE,

BUT THAT PROCESS WOULD
TAKE THOUSANDS OF YEARS.

IF A PLANET DID HIT
TABBY'S STAR,

IT EXPLAINS WHY THE STAR
WAS BRIGHTER A CENTURY AGO.

BUT THIS LONG-TERM DIMMING
IS ONLY HALF THE STORY.

♪♪

WHAT ABOUT THE RECENT,

MORE DRAMATIC DIPS
IN THE STAR'S BRIGHTNESS?

♪♪

NICK HAS AN IDEA FOR THAT, TOO.

HE OBSERVES JUPITER FOR CLUES,

FOCUSING NOT ONLY
ON THE GAS GIANT,

BUT ALSO ON THE PLANET'S MOONS.

JUPITER IS THE LARGEST PLANET
IN OUR OWN SOLAR SYSTEM,

SO IT'S EASILY VISIBLE
THROUGH ANY KIND OF TELESCOPE.

AND YOU CAN ALSO SEE
ITS LARGEST MOONS.

THESE ARE SOME OF THE LARGEST
AND MOST EXTREME MOONS

IN THE ENTIRE SOLAR SYSTEM.

Narrator: NICK SUSPECTS THAT
THE MOONS OF A GIANT PLANET

MIGHT NOT FOLLOW
THEIR PARENT INTO A STAR.

TO CONFIRM HIS HUNCH,
HE USES A COMPUTER SIMULATION

TO SEE WHAT WOULD HAPPEN
TO JUPITER'S MOONS

IF OUR LARGEST PLANET
WERE TO MEET A FIERY END.

Stone: WE WANTED TO UNDERSTAND
WHAT WOULD OCCUR

IF JUPITER
WERE TO COLLIDE WITH OUR SUN.

Narrator: WHAT NICK DISCOVERS
IS STAGGERING.

THREE OF JUPITER'S MOONS DON'T
FOLLOW THE PLANET INTO THE SUN.

♪♪

Stone: CALLISTO,
BEING THE OUTERMOST

OF THE FOUR LARGE MOONS
OF JUPITER,

IS THE FIRST ONE TO GET
STRIPPED AWAY FROM JUPITER

DUE TO THE INFLUENCE
OF THE SUN'S GRAVITY.

AND NOW IT'S BEEN PUT ON
AN ORBIT AROUND THE SUN.

NOW GANYMEDE HAS BEEN PUT
ONTO AN UNSTABLE ORBIT,

AND THERE GOES GANYMEDE.

GANYMEDE'S AWAY.

AND NOW TO EUROPA.

Narrator: IN THE SIMULATION,
THE MOONS CALLISTO, GANYMEDE,

AND EUROPA DON'T HIT THE SUN.

INSTEAD, THEY END UP
ORBITING IT.

COULD SOMETHING SIMILAR HAVE
HAPPENED AROUND TABBY'S STAR?

AND HOW COULD THESE MOONS

BLOCK OUT OVER 20%
OF THE STAR'S LIGHT?

THE ANSWER COULD LIE IN WHAT
THE MOONS ARE MADE FROM.

♪♪

IF THESE MOONS ARE MADE
FROM ICE,

THE STAR'S INTENSE RADIATION

WOULD BLAST
THEIR FROZEN SURFACES.

DEEP BELOW, A SUBTERRANEAN
OCEAN BEGINS TO BOIL.

A VAST CLOUD OF VAPOR AND DUST
BURSTS FROM THE SURFACE

AND ENGULFS THE MASSIVE MOON.

THE MOON ACTS LIKE
A COLOSSAL COMET,

PERHAPS 1.2 MILLION MILES
ACROSS.

THIS JUGGERNAUT CASTS
A GIANT SHADOW

THAT DIMS THE LIGHT
OF TABBY'S STAR.

THIS IS A GREAT THEORY BECAUSE
THE FIRST ONE

THAT WAS PUT FORTH TO EXPLAIN
BOTH THE LONG-TERM DIMMING

AND THE SHORT-TERM DIPS.

Narrator: IF NICK'S RIGHT,

THE CENTURY-LONG DIMMING
OF TABBY'S STAR

IS CAUSED BY A VIOLENT COLLISION
WITH A PLANET

OVER 100 YEARS AGO.

AND TODAY, WE'RE SEEING
THAT PLANET'S LEFTOVER MOONS

ECLIPSING THE STAR'S LIGHT
AS THEY ORBIT.

THIS THEORY SEEMS TO TICK
ALL THE BOXES,

BUT THERE'S A PROBLEM.

THE ODDS DON'T ADD UP.

IT WOULD BE EXTRAORDINARILY
LUCKY TO CATCH A STAR

SHORTLY AFTER
SUCH A CATACLYSMIC EVENT.

Stone: I THINK THE BIGGEST
WEAKNESS OF OUR MODEL

IS THAT IT RELIES ON AN
INTRINSICALLY VERY RARE EVENT --

A COLLISION BETWEEN A PLANET
AND ITS STAR.

IN THAT SENSE,
THE KEPLER SATELLITE

HAD TO GET A LITTLE LUCKY
IN ORDER TO SEE SOMETHING

AS RARE AS THE AFTERMATH
OF A PLANET/STAR COLLISION.

Narrator: SCIENTISTS
ARE STRUGGLING TO FIND

A NATURAL SOLUTION
TO THE MYSTERY OF TABBY'S STAR.

♪♪

BUT THE IDEA THAT THE STAR
HAS A VAST ALIEN SOLAR FARM

AROUND IT
IS STILL IN THE RUNNING.

IT'S TIME TO TEST
IF THIS THEORY IS TRUE.

♪♪

♪♪

♪♪

♪♪

Narrator:
THE STRANGEST STAR IN THE GALAXY

HAS SCIENTISTS PERPLEXED.

♪♪

ITS BRIGHTNESS DIPS,

AS IF SOMETHING
IS PASSING IN FRONT OF IT.

♪♪

COULD IT BE AN
EXTRATERRESTRIAL MEGASTRUCTURE?

♪♪

IN NORTHERN CALIFORNIA,
SETH SHOSTAK IS AN ALIEN HUNTER.

HIS LIFE HAS ONE MISSION --

PROVING WE'RE NOT ALONE
IN THE UNIVERSE.

Shostak: OF COURSE
I THINK THEY'RE OUT THERE.

THERE ARE A TRILLION PLANETS
IN OUR GALAXY.

THERE ARE TWO TRILLION
OTHER GALAXIES WE CAN SEE,

EACH WITH A TRILLION PLANETS.

YOU WANT TO STAND THERE
AND TELL ME,

"BY THE WAY, THIS IS
THE ONLY INTERESTING PLANET"?

Narrator: SETH COMES TO
THE ALLEN TELESCOPE ARRAY

TO USE THESE DISHES TO EAVESDROP

ON ANY RADIO COMMUNICATIONS
COMING FROM THE MEGASTRUCTURE.

Shostak: RADIO WAVES CAN
GO THROUGH THE ENTIRE UNIVERSE

WITHOUT MUCH IMPEDIMENT AT ALL.

WE'RE LOOKING FOR UNNATURAL
RADIO EMISSIONS --

EMISSIONS THAT ARE MADE
BY SOMEBODY WITH A TRANSMITTER,

KLINGONS.

ALL RIGHT, JON. LOOKS LIKE
YOU'RE ALL SET UP HERE.

MAYBE WE COULD
GO TO TABBY'S STAR.

Narrator: SETH AND ENGINEER
JON RICHARDS SET THEIR SIGHTS

ON TABBY'S STAR.

Shostak: OKAY,
ARE THE TELESCOPES SETTLED?

Richards: YEP.

SO WE'RE LOOKING AT
THE CONSTELLATION

OF CYGNUS HERE, I BELIEVE.

AND RIGHT UP HERE,
THIS KIND OF NONDESCRIPT STAR

IS TABBY'S STAR.

I DON'T SEE ANY ALIENS,
BUT ON THE OTHER HAND,

ON THIS SCALE,
YOU PROBABLY WOULDN'T.

THEY SCAN THE STAR ACROSS
BILLIONS OF RADIO FREQUENCIES.

ALL RIGHT, SO WE'RE DOING IT.

Narrator: ARE THEY
ABOUT TO FIND THE FIRST EVIDENCE

OF ALIEN LIFE?

TO LOOK AT SOMETHING LIKE
TABBY'S STAR AND EVEN SUSPECT

THAT IT COULD BE AN ADVANCED
ALIEN CIVILIZATION,

THAT TOUCHES SOMETHING
DEEP INSIDE OF OUR PSYCHES.

YOU SHOULD NOT THROW AWAY IDEAS

SIMPLY BECAUSE
THEY SEEM FARFETCHED.

THEY MIGHT BE RIGHT.

Narrator:
BUT AFTER WEEKS OF HUNTING,

THEY HAVEN'T FOUND ANYTHING YET.

♪♪

YEAH, WE'VE DONE 'EM ALL.
YEAH.

WE DID NOT SEE ANY EVIDENCE OF
E.T. FROM TABBY'S STAR.

♪♪

Shostak: TABBY'S STAR
IS QUITE FAR AWAY,

SO THE TRANSMITTER
WOULD HAVE TO BE QUITE --

QUITE STRONG FOR US TO FIND IT,
BUT WE KEEP LOOKING.

I MEAN, YOU DON'T WANT TO --
YOU DON'T WANT TO WALK AWAY

FROM AN OBJECT AS INTERESTING
AS TABBY'S STAR.

Narrator: IT SEEMS
THE MYSTERIOUS DIMMING

OF TABBY'S STAR
IS PROBABLY NOT ALIEN IN ORIGIN.

Oluyesi: WE'D ALL LIKE
TO FIND LIFE OUT THERE.

THE ALIEN MEGASTRUCTURE
IS PROBABLY NOT THE WAY

WE'RE GONNA FIND IT,
BUT IT GOT US A LITTLE EXCITED.

Narrator: WE'LL HAVE TO WAIT FOR
OUR FIRST GLIMPSE OF E.T. --

FOR NOW, AT LEAST.

Boyajian: WE'RE GONNA FIND
ALIENS ONE DAY. IT'S JUST --

I DON'T REALLY THINK THAT
IT'S GONNA BE THIS STAR.

WHATEVER IS GOING ON WITH
THIS STAR IS GONNA BE

REALLY COOL AND INTERESTING,
BUT I DON'T THINK IT'S ALIENS.

Narrator: SO WHERE DOES THIS
LEAVE SCIENTISTS

HOPING TO SOLVE THE PUZZLE
OF TABBY'S STAR?

THE THEORY THAT COMETS
ARE THE CAUSE HAS PROBLEMS.

IT'S STILL NOT CERTAIN THERE'S
A SECOND STAR TO CREATE A SWARM.

AND HOW COULD COMETS ACCOUNT
FOR THE 100-YEAR DIMMING?

THE IDEA THAT WE'RE SEEING
AN UNTETHERED MOON

ALSO SEEMS LIKE A LONG SHOT.

WE'D HAVE TO GET VERY LUCKY
TO WITNESS SUCH A RARE EVENT.

AND NOW, WITH NO ARTIFICIAL
SIGNALS BEING DETECTED,

THE ALIEN THEORY HAS BEEN
DEALT A MAJOR BLOW.

THAT ONE STAR HAS BEEN
THE SOURCE OF SO MUCH INTRIGUE

THAT ITS MYSTERIES SEEM ONLY
TO DEEPEN WITH TIME, NOT LESSEN.

Narrator: BUT COULD THE MYSTERY
SOON BE SOLVED?

ONE GROUP OF ASTRONOMERS
HAS BEEN MONITORING

THE STAR'S EVERY MOVE.

♪♪

THEY FIND YET ANOTHER
STRANGE BEHAVIOR,

BUT ONE THAT MAY
FINALLY SOLVE THE PUZZLE.

♪♪

♪♪

♪♪

Narrator: IN WEST TEXAS,

ANGELLE TANNER IS PART OF A TEAM
OF ASTRONOMERS

THAT MAKES AN ASTONISHING
DISCOVERY

IN THE QUEST TO SOLVE
THE DEEPENING MYSTERY

OF TABBY'S STAR,

AND THEY DO IT USING

SOME DECIDEDLY MODEST-LOOKING
TECHNOLOGY.

WE ARE HEADING OVER
TO THE LAS CUMBRES TELESCOPE.

Narrator: THIS ISN'T
THE LAS CUMBRES TELESCOPE.

THIS IS.

IT MAY BE SMALL, BUT IT FORMS
PART OF A NETWORK.

THERE ARE OTHER
LAS CUMBRES TELESCOPES

IN PLACES SUCH AS CHILE, HAWAII,
SOUTH AFRICA, AND AUSTRALIA.

EACH IS ROBOTIC, AND THIS
GLOBAL NETWORK ALLOWS SCIENTISTS

TO MONITOR
THE ENTIRE NIGHT SKY 24/7.

WHAT'S VERY NICE ABOUT USING
A NETWORK OF TELESCOPES

IS THAT IT'S ALWAYS
DARK SOMEWHERE.

SO IF THERE ARE CLOUDS IN TEXAS,

IT MIGHT BE CLEAR
IN SOUTH AFRICA,

SO WE'LL CONTINUOUSLY BE ABLE
TO OBSERVE TABBY'S STAR.

Narrator: ANGELLE AND THE TEAM

CAREFULLY OBSERVE
TABBY'S STARLIGHT DIPPING.

THIS TIME, THEY MONITOR THE
COLOR OF THE LIGHT AS IT DIMS.

THEIR OBSERVATIONS REVEAL
SOMETHING EXTRAORDINARY.

IT SEEMS THE STAR'S NOT ONLY
DIMMING, IT'S CHANGING COLOR.

WHAT WE'VE NOTICED LOOKING
AT THE DIPS OF DIFFERENT COLORS

IS THAT THE BLUE LIGHT
IS DIPPING DEEPER

THAN THE RED LIGHT.

SO AS STUFF GOES IN FRONT
OF THE STAR,

IT'S ACTUALLY MAKING THE STAR
APPEAR A LITTLE BIT MORE RED,

AND THAT KIND OF TELLS US
WHAT THE STUFF IS MADE OUT OF.

Narrator:
THE STAR TURNS RED AS IT DIMS.

AND THIS NEW DISCOVERY POINTS
VERY FIRMLY TO A CULPRIT

BECAUSE WE SEE EXACTLY THE SAME
EFFECT WHEN OUR OWN STAR SETS,

AND THE STAR'S LONG RAYS FILTER
THROUGH THE EVENING AIR.

Tanner: HAVING THE SUNSET HERE
IS VERY ANALOGOUS

TO WHAT'S GOING ON
WITH TABBY'S STAR.

THE LIGHT FROM THE SUN
IS ACTUALLY GOING THROUGH

MORE OF THE EARTH'S ATMOSPHERE

THAN IF THE SUN
WAS STRAIGHT ABOVE.

AND NOW WE'RE SEEING THE SUN
ACTUALLY TURN RED

AS IT HITS THE HORIZON.

SUNLIGHT SCATTERS THROUGH
OUR ATMOSPHERE,

AND THE ATMOSPHERE ACTUALLY
SCATTERS AWAY THE BLUE LIGHT,

BUT THE RED LIGHT
COMES RIGHT ON THROUGH.

TABBY'S STAR WAS DOING
SOMETHING SIMILAR.

Narrator: IT'S THE PARTICLES
IN OUR ATMOSPHERE

THAT MAKE OUR SUN APPEAR RED.

AND THAT MEANS WHATEVER BLOCKS
THE LIGHT FROM TABBY'S STAR

MUST BE MADE OF PARTICLES, TOO.

IF THIS WERE A SOLID STRUCTURE
BLOCKING THE STAR,

YOU WOULD EXPECT
RED AND BLUE LIGHT

TO BE BLOCKED JUST AS MUCH.

Narrator: IF SMALL PARTICLES
CAUSE THE DIMMING,

THAT CAN ONLY MEAN ONE THING.

TABBY'S STAR MUST BE SURROUNDED
BY DUST.

THIS DUST COULD BE AN ENORMOUS
DOUGHNUT-SHAPED CLOUD

ORBITING AROUND TABBY'S STAR.

THE RED RAYS PENETRATE THE HAZE,

MAKING THE STAR APPEAR
TO CHANGE COLOR.

AND IF THERE ARE
DENSER PATCHES IN THE CLOUD,

THEY SPORADICALLY DIP
THE STAR'S LIGHT,

WHICH COULD ACCOUNT
FOR THE IRREGULAR DIMMING.

WE THINK THAT THIS DUST
IS PROBABLY VERY SIMILAR

TO THE DUST THAT YOU MIGHT
HAVE IN YOUR HOUSE.

VERY SMALL, VERY TINY
MICROSCOPIC GRAINS OF DUST.

Narrator:
IT'S A CONCLUSIVE RESULT,

BUT IT'S NOT CASE CLOSED.

ASTRONOMERS NOW NEED TO WORK
OUT WHERE THE DUST COMES FROM.

WE'RE NOT QUITE SURE WHERE
THIS DUST IS ORIGINATING FROM

AND HOW IT IS PRODUCED.

THIS IS TELLING US THAT
THERE'S SOMETHING

PROBABLY A LOT MORE COMPLEX
THAT'S GOING ON

THAT WE'RE NOT QUITE SURE
WHAT THAT IS YET.

WHAT COULD CREATE
SUCH A PATCHY HALO?

MAYBE IT IS COMETS OR ICY MOONS

SPEWING OUT DUSTY PLUMES
AS THEY ORBIT TABBY'S STAR.

OR MAYBE THERE'S ANOTHER CAUSE,

ONE THAT SCIENTISTS HAVEN'T
EVEN THOUGHT OF YET.

FOR NOW, AT LEAST,
THE PUZZLE REMAINS UNSOLVED.

UNTIL THEY FIND THAT TRUTH,

ASTRONOMERS WILL CONTINUE
TO MONITOR

TABBY'S STAR'S EVERY FLARE
AND FLICKER.

IN THE END OF THE DAY,
IT'S OBSERVATION,

IT'S THEORIZING,
IT'S CALCULATING ITS MEASUREMENT

THAT WILL TELL YOU
WHAT THE TRUTH IS.

THIS STRANGE LITTLE STAR,
1,500 LIGHT-YEARS FROM EARTH,

HAS TESTED OUR SCIENTISTS
AND THEIR THEORIES TO THE LIMIT.

Oluyesi: THIS EXPERIENCE OF
TRYING TO UNDERSTAND WHAT WE SEE

WHEN WE OBSERVE TABBY'S STAR

IS A GREAT EXAMPLE
OF SEEING SCIENCE IN ACTION.

YOU START OFF WITH
AN OBSERVATION

THAT YOU JUST CAN'T EXPLAIN,

AND YOU JUST PUT
EVERY IDEA OUT THERE --

EVEN ONE AS CRAZY
AS AN ALIEN MEGASTRUCTURE.

♪♪

♪♪

Narrator:
AND AS FOR TABBY HERSELF,

THE LACK OF ANSWERS IS NOT
A CAUSE OF FRUSTRATION.

IT'S THE REASON SHE GETS UP
IN THE MORNING.

WE KNOW THAT NATURE IS A LOT
MORE CREATIVE THAN WE CAN BE,

AND SO JUST --
THESE KINDS OF DISCOVERIES ARE,

YOU KNOW, WHAT KEEPS US GOING
AS THINKERS AND EXPLORERS,

AS THE PEOPLE THAT WE ARE.

WE'RE CURIOUS ABOUT THIS,

AND WE WANT TO UNDERSTAND
WHERE WE COME FROM,

AND WHAT OUR UNIVERSE
HAS TO OFFER US.

♪♪

WE'RE DETECTIVES OF SPACE.

[ LAUGHS ]
THIS IS WHY I DO WHAT I DO.

IT'S -- IT'S A BLAST.

Narrator:
ONLY ONE THING IS CERTAIN --

ONCE THE CASE OF TABBY'S
STRANGELY DIMMING STAR

IS FINALLY CRACKED,

WE'LL LEARN SOMETHING
ABOUT OUR GALAXY

THAT WE NEVER KNEW BEFORE.

Adjusted CORNELDVD