- IN THE PAST, COMETS HAVE SOMETIMES GOTTEN A BAD RAP.
A LOT OF PEOPLE TEND TO BE SUPERSTITIOUS ABOUT THEM,
BLAMING UNFORTUNATE EVENTS
AND NATURAL DISASTERS ON THEIR PRESENCE.
HOWEVER, NASA SAYS THERE IS NOTHING TO FEAR.
AS A MATTER OF FACT, NASA IS QUITE EXCITED
ABOUT COMETS AND WHAT THEY CAN TEACH US.
FIND OUT ABOUT THESE FROZEN MYSTERIES NEXT ON "REAL WORLD."
COMETS ARE COSMIC SNOWBALLS MADE UP OF FROZEN GASES,
ROCK, AND DUST, AND WHEN THEY GET CLOSE ENOUGH TO THE SUN,
ALL THOSE ICES BEGIN TO SUBLIMATE, OR BURN OFF,
AS A DUSTY GAS AND CAN EVEN CREATE
A TEMPORARY ATMOSPHERE AROUND THE COMET CALLED A COMA.
SOLAR WINDS BLOW THOSE GASES AWAY FROM THE SUN,
CREATING THOSE FAMOUS COMET TAILS,
BUT WHAT'S SO INTERESTING ABOUT A BIG CHUNK OF ICE
AND ROCK HURTLING THROUGH SPACE?
- COMETS ARE THE LEFTOVERS OF THOSE ICY CHUNKS,
THOSE ICY BITS THAT WENT INTO MAKING UP THE PLANETS,
SO ONE OF THE GREAT REASONS TO STUDY THEM
IS THAT WE WOULD REALLY LIKE TO KNOW HOW MUCH
OF THE VARIOUS PARTS OF WHAT WENT INTO
MAKING PLANETS ENDED UP ON THE EARTH,
HOW MUCH ENDED UP ON MARS,
HOW MUCH ENDED UP ON VENUS,
AND DOES THAT HELP EXPLAIN
WHY THE DIFFERENT PLANETS ARE SO DIFFERENT?
- JUST AS NO TWO PLANETS ARE EXACTLY ALIKE,
NO TWO COMETS ARE ALIKE EITHER.
COMETS COME IN DIFFERENT SIZES
AND ARE MADE UP OF DIFFERENT MATERIALS.
ALTHOUGH THE COMET'S COMA AND TAIL ARE FASCINATING TO SEE,
SCIENTISTS DETERMINE THE SIZE OF A COMET
BY MEASURING THE DIAMETER OF ITS NUCLEUS.
THE DIAMETER IS THE DISTANCE ACROSS
A SPHERE RIGHT THROUGH THE MIDDLE.
BECAUSE OF SOLAR RADIATION,
COMETS LOSE MASS AS THEY ORBIT THE SUN.
THIS MASS LOSS CAN TELL US A LOT ABOUT THE LIFE OF A COMET
AND WHERE IT MIGHT HAVE COME FROM.
- EVERY TIME A COMET COMES IN NEAR THE SUN,
IT'S GONNA LOSE SOME MASS.
SO THE LIFETIME OF A COMET,
HOW LONG IT'S ACTUALLY GONNA SURVIVE AS AN ENTITY
IN THE SOLAR SYSTEM DEPENDS ENTIRELY
ON HOW MUCH MASS IT LOSES EVERY TIME IT COMES AROUND THE SUN.
SOME COMETS COME IN SO CLOSE TO THE SUN,
THEY LOSE SO MUCH MASS THAT THEY DON'T EVEN SURVIVE
THE TRIP AROUND THE SUN.
WHEREAS OTHERS, LIKE THE FAMOUS HALLEY'S COMET,
CAN SURVIVE MANY, MANY TRIPS AROUND THE SUN
BECAUSE THEY DON'T LOSE NEARLY AS MUCH MASS.
- FROM TIME TO TIME, A COMET IS IN JUST THE RIGHT PLACE
IN OUR SOLAR SYSTEM THAT HUMANS CAN LOOK UP
AND SEE A BRIGHT OBJECT IN THE SKY.
ONE COMET THAT HAS NASA LOOKING TO THE SKY IS COMET ISON.
- AND THIS IS PROBABLY COMET ISON'S FIRST TRIP PAST THE SUN.
IT'S A YOUNG COMET.
WE SPEAK OF THEM AS BEING YOUNG BECAUSE THEY'VE ONLY BEEN
PAST THE SUN ONCE OR MAYBE A COUPLE OF TIMES.
THIS IS PROBABLY COMET ISON'S ONLY TRIP PAST THE SUN.
IT'S ON WHAT WE CALL A HYPERBOLIC TRAJECTORY,
WHICH MEANS THAT AFTER IT GOES AROUND THE SUN,
WE'RE ACTUALLY GONNA LOSE IT FROM THE SOLAR SYSTEM.
IT'S GONNA BE COMPLETELY EJECTED FROM THE SOLAR SYSTEM
AND GO WANDERING AROUND THROUGH INTERSTELLAR SPACE.
SO COMET ISON CAME FROM VERY FAR OUT
IN THE OUTER, OUTERMOST REGIONS OF THE SOLAR SYSTEM.
IT'S COME IN.
THIS IS ITS 15 SECONDS OF FAME,
AND THEN IT'S GONNA BE GONE FOREVER,
SO IT'S VERY INTERESTING TO STUDY THESE OBJECTS,
BECAUSE WE DON'T GET VERY MANY OPPORTUNITIES.
- THIS COMET HAS SPENT THE LAST FEW MILLION YEARS
COMING TO US FROM THE FAR REACHES OF THE OORT CLOUD,
WHERE IT HAS BEEN IN DEEP FREEZE FOR BILLIONS OF YEARS.
BUT AS THE COMET GETS CLOSER TO THE SUN,
IT WILL BOIL AND EVAPORATE AND LOSE MUCH OF ITS MASS
AS THE MATERIAL FROM THE BEGINNING OF TIME
STREAMS ACROSS THE SOLAR SYSTEM.
NASA HAS USED SEVERAL OF THE TOOLS IN ITS BAG
TO GET A BETTER LOOK AT THE HEAVENLY PHENOMENON.
SPACECRAFT LIKE DEEP IMPACT, SPITZER, SWIFT,
AND EVEN THE HUBBLE SPACE TELESCOPE
HAVE OBSERVED COMET ISON AND HAVE GIVEN US
SOME PRETTY INTERESTING PICTURES OF THIS UNIQUE COMET.
BUT THAT'S NOT ALL.
NASA INTENDS TO OBSERVE COMET ISON
WITH ALL AVAILABLE TOOLS AT THEIR DISPOSAL,
INCLUDING SOHO, STEREO,
SDO, CHANDRA SPACE TELESCOPE,
MESSENGER, THE INTERNATIONAL SPACE STATION,
MARS RECONNAISSANCE ORBITER,
AND EVEN THE MARS CURIOSITY ROVER.
COMET ISON WILL HELP SCIENTISTS GATHER
THE MOST COMPREHENSIVE PACKAGE OF DATA
EVER COLLECTED ABOUT A SINGLE COMET.
WHO KNOWS WHAT WE'LL LEARN, BUT JUST WATCHING A COMET
ISN'T ENOUGH FOR NASA OR OUR INTERNATIONAL PARTNERS IN SPACE.
THE EUROPEAN SPACE AGENCY HAS LAUNCHED A COMETARY FIRST.
THE ROSETTA SPACECRAFT WILL RENDEZVOUS WITH A COMET
AND LAND ROBOTIC INSTRUMENTS ON THE SURFACE.
NASA HAS SEVERAL INSTRUMENTS ABOARD ROSETTA,
INSTRUMENTS THAT WILL HELP US UNDERSTAND
HOW A COMET DEVELOPS ITS COMA AND TAILS,
HOW A COMET'S CHEMICALS INTERACT WITH EACH OTHER
AND WITH THE SUN,
AND HOW THE COMET WAS FORMED IN THE FIRST PLACE.
- WE HAVE VISITED COMETS WITH LITTLE FLYBY KINDS OF PROBES,
BUT THIS IS THE FIRST ATTEMPT
TO ACTUALLY NOT ONLY GO INTO ORBIT AROUND THE COMET NUCLEUS
AND OBSERVE IT VERY CLOSELY, BUT ALSO TO LAND ON THE SURFACE,
AND SO IT'S GONNA PROVIDE US, REALLY,
THE MOST IN-DEPTH UNDERSTANDING OF WHAT COMETS ARE MADE OF
AND HOW THEY BEHAVE AND WHAT THEIR DYNAMICS ARE
AND HOW THEY EVOLVE OVER TIME.
ONE OF THE BIGGEST CHALLENGES, ACTUALLY,
HAS BEEN THE DURATION OF THIS MISSION.
BECAUSE WE'RE TRYING TO CATCH UP WITH A COMET,
IT'S NOT JUST STRAIGHTFORWARD.
YOU CAN'T JUST DRIVE TO THE COMET.
YOU'VE GOT TO SYNC UP YOUR ORBIT WITH THE COMET
SO AS IT'S GOING AROUND THE SUN, YOU JOIN UP WITH IT--
SMOOTHLY, BECAUSE WE DON'T WANT TO FLY PAST IT REAL FAST.
WE ACTUALLY WANT TO GO INTO ORBIT AROUND IT,
SO WE HAVE TO SMOOTHLY CATCH UP WITH IT.
AND THAT'S NOT EASY.
COMETS TEND TO BE GOING PRETTY QUICKLY.
THEY'RE ON RATHER ODD ORBITS
COMPARED TO THINGS LIKE THE EARTH,
AND SO ROSETTA'S TRAJECTORY HAS TAKEN IT PAST THE EARTH
A COUPLE OF TIMES.
IT'S TAKEN A ZING PAST-- A SLING PAST MARS,
AND WE'VE BEEN USING THESE PLANETARY ENCOUNTERS
TO SYNC UP THE ORBIT WITH THE COMET.
- SO WHILE YOU'RE WAITING FOR NEWS ABOUT THE COMET ISON
OR THAT NEXT EXCITING COMET MISSION,
CHECK OUT COMET QUEST, A GAME CREATED BY NASA'S SPACE TEAM.
JUST LIKE THE REAL ROSETTA MISSION,
YOU CAN HITCH A RIDE ON A COMET AS IT JOURNEYS TOWARDS THE SUN,
AND JUST LIKE NASA, YOU MAY HAVE TO USE
A LITTLE BIT OF MATH TO MEET THE CHALLENGE.
I'M DIEGO, AND SEE YOU NEXT TIME ON "REAL WORLD."
- AND NOW FOR AN UPDATE ABOUT COMET ISON.
AS NASA DETERMINES THE FINAL STATUS OF ISON,
MOST AGREE THAT THE COMET WAS DESTROYED
AS IT ROUNDED THE SUN, LEAVING BEHIND
ONLY PIECES OF RUBBLE,
BUT EVEN THOSE DUSTY FRAGMENTS HAVE A STORY TO TELL.
COMET ISON, WHICH BEGAN ITS JOURNEY FROM THE OORT CLOUD
SOME 3 MILLION YEARS AGO,
MADE ITS CLOSEST APPROACH TO THE SUN ON NOVEMBER 28, 2013.
REGARDLESS OF ITS FATE,
COMET ISON DID NOT DISAPPOINT RESEARCHERS.
OBSERVATORIES AROUND THE WORLD AND IN SPACE
GATHERED THE LARGEST SET OF COMET OBSERVATIONS OF ALL TIME,
WHICH SHOULD PROVIDE ENOUGH DATA FOR PROFESSIONAL
AND AMATEUR ASTRONOMERS TO STUDY FOR YEARS TO COME.