WEBVTT

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[dramatic percussion music]

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- HI, WELCOME
TO "NASA LAUNCHPAD."

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I'M YOUR HOST, JUSTIN TULLY.

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SO WHEN I SAY "KEPLER,"
WHAT FLASHES IN YOUR MIND?

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JOHANNES KEPLER, RIGHT?

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GERMAN MATHEMATICIAN,
ASTRONOMER, ASTROLOGER,

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AND KEY FIGURE

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IN THE 17TH-CENTURY
SCIENTIFIC REVOLUTION.

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HIS LAWS OF PLANETARY MOTION

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LED NEWTON
TO HIS LAW OF GRAVITATION.

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BUT YOU KNEW ALL THAT, RIGHT?

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BUT THERE'S A NEW KEPLER
IN TOWN.

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ACTUALLY, IT'S NAMED
AFTER THE OLD KEPLER,

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AND ACTUALLY,
IT'S NOT IN TOWN ANYMORE

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SINCE IT WAS LAUNCHED
INTO SPACE ON MARCH 6, 2009.

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ANYWAY, IT'S NASA'S
NEW KEPLER SPACECRAFT,

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AND IT'S NASA'S FIRST MISSION

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CAPABLE OF FINDING EARTH-SIZE
AND SMALLER PLANETS

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AROUND OTHER STARS.

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THE KEPLER MISSION
WILL BE LOOKING CONTINUOUSLY

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AT OVER 100,000 STARS
IN ONE REGION OF THE SKY,

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IN THE CYGNUS
AND LYRA CONSTELLATIONS.

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THE FIELD OF VIEW
IS EXTREMELY LARGE

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FOR AN ASTRONOMICAL TELESCOPE.

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MOST TELESCOPES,
SUCH AS HUBBLE SPACE TELESCOPE,

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ONLY VIEW A SMALL REGION
AT ONE TIME.

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IT'S ABOUT THE SIZE OF A GRAIN
OF SAND HELD AT ARM'S LENGTH.

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KEPLER COVERS
A MUCH LARGER FIELD,

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ABOUT A HAND AT ARM'S LENGTH.

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THE FIELD OF VIEW
IS OVERHEAD AT MIDNIGHT

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IN THE MIDDLE OF SUMMER

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FOR THOSE
IN THE MID-NORTHERN LATITUDES

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AND EARLIER IN THE EVENING
IN LATE SUMMER AND FALL.

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KEPLER USES
THE TRANSIT METHOD

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TO DETECT THE EXISTENCE
OF A PLANET.

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A TRANSIT OCCURS
WHEN A PLANET

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PASSES IN FRONT
OF ITS PARENT STAR

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AND BLOCKS A BIT OF STARLIGHT
WHILE DOING SO.

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WITHIN OUR OWN SOLAR SYSTEM,

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WE CAN OBSERVE
PLANETARY TRANSITS

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OF MERCURY AND VENUS
FROM EARTH

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WHEN THEY PASS
IN FRONT OF THE SUN.

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THE PHENOMENON
IS MUCH LIKE AN ECLIPSE.

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ALTHOUGH THE PLANETS
ARE LARGER THAN OUR MOON,

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THEY ARE ALSO
MUCH FARTHER AWAY,

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SO THE TRANSIT JUST LOOKS
LIKE A SMALL BLACK DISK

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MOVING OVER THE FACE
OF THE SUN.

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KEPLER WILL OBSERVE
THE SAME PHENOMENA

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IN ORDER TO DETECT
EARTH-SIZE PLANETS

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BUT FROM VERY FAR AWAY.

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IN FACT, THE DISTANT SUNS
THAT KEPLER WILL OBSERVE

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ARE SO FAR AWAY THAT THE STARS
ARE JUST POINTS OF LIGHT.

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DETECTING AN EARTH-SIZE PLANET
TRANSITING A DISTANT STAR

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IS LIKE OBSERVING A GNAT FLYING
IN FRONT OF A CAR'S HEADLIGHT

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SEEN FROM MANY MILES AWAY.

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THE PROBLEM
IS THAT THE ORIENTATIONS

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OF PLANET ORBITS
IN OTHER SOLAR SYSTEMS

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ARE RANDOMLY ALIGNED.

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SOME MAY EVEN ORBIT FACE-ON.

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ONLY ABOUT 1% OF THE PLANETS
ARE ALIGNED

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SO THAT THEY CAN BE DETECTED
BY THE TRANSIT METHOD.

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HENCE, TO DETECT
A LARGE NUMBER OF PLANETS,

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WE CAN'T JUST LOOK
AT A FEW STARS.

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HUNDREDS OR EVEN THOUSANDS
OF STARS ARE NOT ENOUGH.

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WITH KEPLER, THE SCIENTISTS
WILL BE OBSERVING

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OVER 100,000 STARS AT ONCE
TO FIND EARTH-SIZE PLANETS.

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KEPLER DOES NOT DIRECTLY OBSERVE
THE IMAGE OF A PLANET.

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RATHER, IT OBSERVES
THE EFFECT THE PLANET HAS

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ON ITS PARENT STAR.

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IF THE ORBIT OF THE PLANET
IS ALIGNED

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ALONG KEPLER'S LINE OF SIGHT
TO THE STAR,

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IT WILL BLOCK
A VERY TINY AMOUNT OF LIGHT

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COMING FROM THE STAR
TO THE KEPLER TELESCOPE.

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THE TELESCOPE
WILL IMAGE THE LIGHT

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FROM MANY STARS AT ONCE.

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IT USES 42 CCDs,
CHARGE-COUPLED DEVICES,

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DETECTORS SIMILAR TO THOSE
IN COMMERCIAL DIGITAL CAMERAS.

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BUT THESE ARE MUCH LARGER,

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HAVING A TOTAL
OF 95 MEGAPIXELS.

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WITH THE CCDs,
KEPLER IS CAPABLE

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OF OBSERVING
OVER 100,000 STARS ALL AT ONCE

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AND MEASURING THEIR BRIGHTNESS
TO AN ACCURACY

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OF BETTER
THAN 1 PART IN 100,000,

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OR 10 PARTS PER MILLION.

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THIS IS EQUIVALENT
TO WATCHING A FOOTBALL GAME

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FROM THE CAMERA BLIMP

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AND DETECTING EVERY TIME
JUST ONE PERSON

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WALKS IN OR OUT
OF THE STADIUM.

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THE RESULTS FROM KEPLER
WILL COME

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FROM MEASURING THE BRIGHTNESS
OF THE STARS.

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THE DATA WILL LOOK LIKE AN EKG
SHOWING THE HEARTBEAT.

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WHENEVER A PLANET PASSES
IN FRONT OF ITS PARENT STAR

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AS VIEWED FROM OUR SOLAR SYSTEM,

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IT PRODUCES A TINY PULSE,
OR BEAT.

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FROM THE REPEATED BEATS,
WE CAN DETECT AND CONFIRM

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THE EXISTENCE
OF EARTH-SIZE PLANETS

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AND LEARN ABOUT THE ORBIT
AND SIZE OF THE PLANET.

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A HABITABLE PLANET,

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ONE THAT CAN HAVE LIQUID WATER
ON ITS SURFACE,

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MUST BE BETWEEN ABOUT 80%
AND 200% THE DIAMETER OF EARTH.

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PLANETS THAT ARE SMALLER
THAN 8/10 OF AN EARTH DIAMETER

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HAVE LESS THAN HALF
AN EARTH MASS

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AND DO NOT HAVE
ENOUGH GRAVITY

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TO HOLD ON
TO A LIFE-SUSTAINING ATMOSPHERE.

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PLANETS THAT ARE MORE THAN TWICE
THE DIAMETER OF EARTH

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HAVE ABOUT TEN EARTH MASSES

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AND ENOUGH GRAVITY
TO HOLD ON TO HYDROGEN,

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THE MOST ABUNDANT ELEMENT
IN THE UNIVERSE.

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SUCH LARGE PLANETS
TURN INTO GAS GIANTS

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LIKE JUPITER AND SATURN.

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THE HABITABLE ZONE
IS THE DISTANCE FROM A STAR

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WHERE ONE CAN HAVE LIQUID WATER
ON THE SURFACE OF A PLANET.

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IF A PLANET IS TOO CLOSE
TO ITS PARENT STAR,

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IT WILL BE TOO HOT,
AND WATER WOULD HAVE EVAPORATED.

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IF A PLANET IS TOO FAR
FROM A STAR,

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IT'S TOO COLD,
AND THE WATER IS FROZEN.

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STARS COME IN A WIDE VARIETY

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OF SIZES, MASSES,
AND TEMPERATURES.

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STARS THAT ARE SMALLER, COOLER,
AND LOWER MASS THAN THE SUN

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HAVE THEIR HABITABLE ZONE

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MUCH CLOSER TO THE STAR
THAN THE SUN.

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STARS THAT ARE LARGER, HOTTER,
AND MORE MASSIVE THAN THE SUN

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HAVE THEIR HABITABLE ZONE
MUCH FARTHER OUT FROM THE STAR.

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SO KEEP YOUR EARS AND EYES OPEN
FOR NEWS ABOUT KEPLER.

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WHO KNOWS?

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A FEW YEARS DOWN THE ROAD,

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WHEN ALL THAT THOSE LIGHT CURVES
ARE PROCESSED,

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MAYBE WE'LL HAVE FOUND
A FEW PLANETS

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THAT ARE SIMILAR TO EARTH.

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HOW EXCITING WOULD THAT BE, HUH?

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THAT'S IT FOR NOW.

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FOR "NASA LAUNCHPAD,"
I'M JUSTIN TULLY.

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WE'LL CATCH YOU NEXT TIME.