Series titles
THIS IS THE SUN AS MOST OF US KNOW IT... A FEATURELESS, GOLDEN DISK...
THE BRINGER OF DAY... THE FIERY TORCH OF SUNSET...
THE SOURCE OF LIGHT AND LIFE...
THE ULTIMATE "REASON FOR THE SEASONS", WHOSE PASSAGE ACROSS THE SKY IS THE VERY SYMBOL OF REGULARITY.
THE SUN WAS RA TO THE EGYPTIANS... A GOD TO SOCIETIES EAST AND WEST... THE RULER OF THE HEAVENS.
...AN ALL-SEEING EYE UNDER WHOSE GAZE TIME AND HUMAN SOCIETIES PASS LIKE EDDIES IN A STREAM...
(music shock cut)
BUT THIS IS THE SUN KNOWN TO MODERN SCIENCE.
THE SUN AS WE NOW KNOW IT IS ANYTHING BUT FEATURELESS. IT'S A PLACE OF AWESOME CHANGE.
VAST FLARES UNLEASH COLOSSAL ENERGIES...
TELESCOPES SHOW US VISIBLE LAYERS BOILING IN CEASELESS TURMOIL...
SPACECRAFT REVEAL SHIMMERING MAGNETIC FIELDS...
NOW WE CAN TRACK ITS BEHAVIOR THROUGHOUT ITS 11-YEAR SUNSPOT CYCLE.
TODAY WE KNOW OUR SUN IS A MAGNETIC, VARIABLE STAR, AND THAT EVEN THE "QUIET" SUN IS VERY ACTIVE.
THESE AMAZING IMAGES COME FROM A NEW GENERATION OF SOLAR SPACECRAFT, LIKE "SOHO."
AND THE PICTURES ARE STUDIED BY A NEW GENERATION OF SPACE SCIENTISTS, LIKE BARBARA THOMPSON AND HER COLLEAGUES AT NASA'S GODDARD SPACEFLIGHT CENTER
name title: BARBARA THOMPSON
NASA Goddard Space Flight Center
Once in a while, you sit back and you realize how enormous the Sun is, and that it's an actual star. You're not looking at some little small object, like it looks like on the screen. This is a whole star.
chapter head graphic:
HOW DOES THE SUN WORK?
sub-heads: Fusion, Convection, Magnetism
IN THIS PROGRAM YOU'LL DISCOVER HOW THE SUN WORKS, AND THE FORCES WHICH POWER IT.
chapter head: sun (as in a dictionary)
YOU'LL SEE THAT OUR SUN IS A STAR... AND LEARN ABOUT ITS SIZE, COLOR AND TEMPERATURE...
chapter head: THE SUN-EARTH CONNECTION
YOU'LL FIND OUT HOW THE SUN AFFECTS THE EARTH... AND HOW WE STUDY IT.
chapter head: HOW DOES THE SUN WORK?
THE ULTIMATE SOURCE OF THE LIGHT AND HEAT ON WHICH WE RELY IS FOUND IN THE CORE OF THE SUN.
HERE TEMPERATURES REACH NEARLY 16 MILLION DEGREES, AND PRESSURE MAKES THE GASES 13 TIMES DENSER THAN LEAD-THOUGH THERE'S NOTHING SOLID HERE.
IN THESE EXTREME CONDITIONS, THE SIMPLEST OF ATOMIC PARTICLES-PROTONS, THE NUCLEI OF HYDROGEN ATOMS-SMASH INTO EACH OTHER AT SUCH GREAT SPEED THAT THEY FUSE TOGETHER.
IN A CHAIN OF REACTIONS, HELIUM, THE SECOND MOST ABUNDANT GAS IN THE UNIVERSE, IS CREATED-AND A SMALL AMOUNT OF MASS IS LOST. AND THAT MASS, AS EXPRESSED IN ALBERT EINSTEIN'S FAMOUS E=mc2, (capital E equals little m little c squared) BECOMES ENERGY.
THOUGH THE AMOUNT OF MASS LOST IS LESS THAN 1%, SINCE 700 MILLION TONS OF HYDROGEN BECOME HELIUM EVERY SECOND, A TREMENDOUS AMOUNT OF ENERGY IS CREATED!
SOME OF THIS ENERGY LEAVES THE CORE, AND LITERALLY BOUNCES AROUND IN THE RADIATIVE ZONE-WITH SOME PARTICLES TAKING AS LONG AS 170,000 YEARS TO MAKE IT UP TO THE NEXT LAYER.
HERE CONVECTION CURRENTS TRANSPORT HEAT ENERGY TO THE SUN'S SURFACE... THIS TIME TAKING ONLY 10 DAYS!
THE HOT MATERIAL-SEEN HERE AS WHITE-RISES, COOLS AND THEN SINKS BACK DOWN... WE CALL THESE SHAPES "GRANULES."
EACH IS ABOUT 1,000 KILOMETERS ACROSS, AND LASTS FOR JUST A FEW MINUTES BEFORE DISAPPEARING.
YOU CAN SEE EXACTLY THE EXACT SAME CONVECTION PATTERNS IN A POT OF BOILING SOUP ON A STOVE!
IF WE COULD HOVER JUST ABOVE THE TOP OF THE SUN, THIS IS WHAT IT MIGHT LOOK LIKE.
HUGE CELLS OF HOT GAS BILLOW UP, A LITTLE LIKE CUMULUS STORM CLOUDS HERE ON EARTH.
THIS IS THE "PHOTOSPHERE"-"THE SHELL OF LIGHT" AND IT'S ABOUT 300 KM THICK, AND 6,000 DEGREES.
OFF IN THE DISTANCE YOU CAN SEE A PROMINENCE-GASES SOMEWHAT COOLER THAN PHOTOSPHERE, HELD UP BY MAGNETIC FIELD LINES EMERGING FROM DEEP DOWN BELOW IN THE SUN.
THE PHOTOSPHERE IS THE REGION WHICH RELEASES THE VISIBLE SUNLIGHT WHICH EVENTUALLY-8.3 MINUTES LATER-REACHES US HERE ON EARTH.
"Sun Spots" graphic
OUR SUN IS HUGE AND VERY FAR AWAY... HOW CAN WE BRING ITS SIZE AND DISTANCE DOWN TO EARTH?
THE SUN'S DIAMETER IS ONE POINT FOUR MILLION KILOMETERS-THAT'S 109 TIMES THE SIZE OF EARTH'S!
AND ONE MILLION EARTH'S WOULD FIT INSIDE THE SUN.
AS FOR DISTANCE, IF THE SUN WAS A BASKETBALL AT THE OTHER END OF THE COURT, OUR PLANET WOULD BE A BALL-BEARING, AT THIS END.
LIGHT, THE FASTEST THING IN THE UNIVERSE, TAKES 8.3 MINUTES TO TRAVEL FROM THE SUN TO EARTH...
BUT AT 55 MILES PER HOUR, IT WOULD TAKE YOU 193 YEARS TO DRIVE TO THE SUN, OUR NEAREST, DAYTIME, STAR!
WE'VE SAID THE PHOTOSPHERE IS 6,000 DEGREES, BUT WITH THE SUN SO FAR AWAY, HOW CAN WE TELL JUST HOW HOT IT REALLY IS?
name title:
CRAIG DeFOREST
NASA Goddard Space Flight Center
Sometimes people ask, "How can me measure the temperature of the surface of the Sun?" Well we can't measure it directly, we can't put a thermometer there. But we can measure the color at which it's glowing. Now things that are hot, glow. They glow at a particular color that's characteristic of their temperature. So what that means is, if you turned something, like an incandescent light bulb on, and it glows orange, that's the same temperature as anything in the Universe that's glowing orange.
Here's a set of safety goggles. Alright, so the surface of the Sun glows a sort of orangey-yellow color because it's at about six thousand degrees Kelvin. Well we can't get that hot here with this equipment, we can only get up to about 5300 Fahrenheit, which is about 3500 Kelvin. So we can't quite make it glow as hot as the surface (of the Sun), but there are other types of equipment that can get that hot.
(lights blow-torch: roar)
All right, now the tip of this flame is about 3500 degrees Kelvin and we're going to apply it to this ordinary bathroom tile, and you can see that the tile is starting to glow. Alright. It might look like the flame to you, but if I move this, you can see that the tile itself is hot, and not just the flame. Now we can't measure this tile directly here, because I don't have a pyrometer, a thermometer that could measure it, but in the laboratory we could. And by comparing the temperature of the tile, to the color at which it's glowing, we can determine the temperature of the Sun, and other distant stars that are millions of times farther away.
SO A STAR'S COLOR IS A CLUE TO ITS TEMPERATURE... AND ASTRONOMERS ARRANGE STARS BY COLOR AND TEMPERATURE IN ORDER TO STUDY THEM.
OUR SUN IS IN THE MIDDLE OF THIS DIAGRAM, INDICATED BY THE ARROW.
BLUE STARS ARE THE HOTTEST: SOME OF THEM REACH 20,000 DEGREES, 3 TO 4 TIMES HOTTER THAN THE SUN. THESE STARS BURN UP QUICKLY, AND DIE YOUNG.
STARS COOLER THAN THE SUN GLOW MORE ORANGE. SOME RED STARS ARE ONLY 3,000 DEGREES, JUST LIKE THAT TILE.
THOUGH DIM, SOME RED GIANTS CAN BE 1,000 TIMES THE DIAMETER OF OUR STAR.
OUR SUN IS "IN BETWEEN", IN COLOR, SIZE AND TEMPERATURE.
BUT WE THINK OUR STAR IS JUST LIKE ALL OTHER STARS IN THE WAY THAT ITS ACTIVITY IS DRIVEN BY MAGNETISM.
THAT'S BECAUSE STARS ARE "PLASMA."
titles: "PLASMA", "SOLID", "LIQUID" AND "GASEOUS."
PLASMA IS THE 4TH STATE OF MATTER IN OUR UNIVERSE, ALONG WITH THE MUCH MORE FAMILIAR "SOLID", "LIQUID" AND "GASEOUS."
IN THE SUN'S PLASMA, ATOMS HAVE LOST THEIR NORMAL COMPLEMENT OF ELECTRONS.
THEY'RE NO LONGER ELECTRICALLY NEUTRAL BUT CAN BECOME ELECTRICALLY CHARGED.
A SIMPLE HANDS-ON EXPERIMENT WILL SHOW YOU THAT BY PASSING ELECTRICITY THROUGH A METAL YOU CAN TURN IT INTO A MAGNET. SOMETHING SIMILAR HAPPENS ON THE SUN.
ELECTRICALLY-CHARGED PLASMA WHIRLS AROUND, AND GENERATES VAST MAGNETIC FIELDS.
THE SUN'S EQUATOR AND POLES ROTATE AT DIFFERENT RATES.
NEW DATA FROM SPACECRAFT HAS ENABLED US TO GIVE THE SUN A KIND OF CAT-SCAN AND SEE THAT GASES AT DIFFERENT DEPTHS ALSO ROTATE AT DIFFERENT SPEEDS-CREATING MORE MAGNETISM, RATHER LIKE A DYNAMO DOWN HERE ON EARTH.
OVER TIME, MAGNETIC FIELD LINES GET WOUND UP, TIGHTER AND TIGHTER.
EVENTUALLY, SOME OF THEM BREAK, AND RE-CONNECT IN NEW PATTERNS.
WE NOW KNOW THAT SUNSPOTS ARE CAUSED BY STRONG, LOCAL MAGNETIC FIELDS, THOUSANDS OF TIMES STRONGER THAN EARTH'S MAGNETIC FIELD.
THESE FIELDS SLOW DOWN THE TURBULENT CONVECTION PATTERNS, AND TURN DOWN THE HEAT.
BECAUSE THEY ARE TWO TO THREE THOUSAND DEGREES COOLER, SUNSPOTS APPEAR DARKER THAN THEIR HOTTER SURROUNDINGS.
MAGNETIC FORCES ALSO SHAPE THE PROMINENCES WE'VE SEEN.
SOMETIMES, JUST LIKE ELASTIC BANDS WOUND TOO TIGHT, THEY BREAK, RELEASING VAST ENERGIES.
name title: ART POLAND
These magnetic field we see, especially over these prominences, these cool gases, these cool clouds, every once in a while, these things blow off of the Sun, ejecting a million tons of matter at a million miles an hour, out into space. In fact I think it's a billion tons of matter at a million miles an hour, out into space. Sometimes these come crashing into the Earth even.
Chapter head graphic THE SUN-EARTH CONNECTION
ONE WAY THESE EXPLOSIONS ON THE SUN CAN AFFECT EARTH IS BY IMPACTING THE SATELLITES ON WHICH OUR GLOBAL CIVILISATION DEPENDS.
AND THE CLUE THAT SOMETHING'S HAPPENING IS THE AURORA, THE "NORTHERN" OR "SOUTHERN" LIGHTS.
THESE MASSIVE ERUPTIONS OF MATTER AND ENERGY ARE CALLED CME'S-"CORONAL MASS EJECTIONS"-AND THEY ARE FIRST SEEN BY THE SOHO SPACECRAFT.
THIS DISTINCTIVE HALO PATTERN MEANS THE CME IS HEADED DIRECTLY FOR EARTH-AND WE MAY BE IN FOR SOME STORMY "SPACE WEATHER"!
SOMETIMES WHEN THEY ARRIVE AT EARTH, THE MAGNETIC FIELD IN THE SOLAR WIND INTERACTS WITH EARTH'S OWN MAGNETIC FIELD AND RESULTS IN THE CHARGING OF PARTICLES ALREADY PRESENT IN EARTH'S RADIATION FIELDS.
IT'S THESE CHARGED PARTICLES WHICH THEN CREATE THE AURORAS SEEN AROUND EARTH'S NORTH AND SOUTH POLES.
THIS KIND OF DISTURBANCE CAN UNLEASH ENERGY BACK TOWARD EARTH FROM THE NIGHT-SIDE OF THE PLANET... RIGHT INTO THE REGIONS OF LOW-EARTH ORBIT WHERE SOME OF OUR MOST IMPORTANT SATELLITES RESIDE.
SOMETIMES THE EFFECTS ARE FELT STILL CLOSER TO HOME.
IN MARCH 1989, EARTH EXPERIENCED A STRONG GEOMAGNETIC STORM.
"HYDROQUEBEC," THE 3RD LARGEST POWER GRID IN NORTH AMERICA, FAILED.
MILLIONS OF HOMES LOST ELECTRICITY.
GENERATORS AS FAR SOUTH AS NEW JERSEY WERE FRIED.
HOSPITALS SWITCHED TO EMERGENCY POWER.
WITHIN MINUTES STORMY SPACE WEATHER STRETCHED CLEAR AROUND THE PLANET.
THE REASON? JUST LIKE EARTH, THE SUN HAS SEASONS, AND THIS VAST BLACKOUT HAPPENED DURING THE PEAK OF THE PREVIOUS "SOLAR MAXIMUM."
EVERY 11 YEARS, THE NUMBER OF SUNSPOTS RISES AND FALLS... AND THE SPOTS ALSO CHANGE POSITION ON THE SUN.
AT THE HEIGHT OF THE CYCLE THERE ARE MORE SUNSPOTS, MORE STORMS ON THE SUN, AND THE GREATER LIKELIHOOD OF EFFECTS DOWN HERE ON EARTH.
HERE'S A TIMELAPSE PORTRAIT OF HOW THE SUN'S FACE CHANGES...
FROM RELATIVELY STABLE...
TO MORE ACTIVE...
TO PEAK ACTIVITY.
YOU DON'T HAVE TO BE A SOLAR ASTRONOMER TO RECOGNIZE THE DIFFERENCE:
ON THE LEFT, THE SUN IN CALMER YEARS...
AND ON THE RIGHT, WITH ACTIVITY RAMPING UP.
IN 2000 AND 2001 WE'RE ONCE MORE IN "SOLAR MAXIMUM", AND TRUE TO FORM, ON JULY 14, 2000, THE BIGGEST SUN STORM IN 10 YEARS HIT.
BUT THIS TIME "PLANET EARTH" WAS WATCHING, AND READY TO ACT.
TELESCOPES SINGLED OUT SUNSPOT GROUP 9077 AS READY TO BLOW...
THE "SOHO" SATELLITE RECORDED THE FLARE BEGINNING... AND SPREADING.
THEN IT SAW THE TELL-TALE HALO OF A "CME", AND A SPRAY OF ENERGETIC PROTONS ZAPPED THE CAMERA.
MEANWHILE THE "TRACE" SATELLITE TOOK THESE INCREDIBLE CLOSE-UP VIEWS... SHOWING HOW >TANGLED< MAGNETIC FIELD LINES HAD >BROKEN APART< AND >RECONNECTED<, RELEASING PHENOMENAL ENERGIES.
MOVING AT 4 MILLION MILES PER HOUR THE STORM HIT EARTH AND THE "POLAR" SATELLITE SAW AURORAS AS FAR SOUTH AS FLORIDA.
THERE WERE GLITCHES ON SPACECRAFT, BUT FEWER PROBLEMS DOWN HERE ON EARTH, THANKS-IN PART-TO A NEW EARLY WARNING SYSTEM IN WHICH NOAA AND NASA WORK TOGETHER TO FORECAST "SPACE WEATHER," JUST LIKE HURRICANES OR WINTER WEATHER.
WITH SUNSPOT NUMBERS PEAKING AND "SOLAR MAXIMUM" AT ITS HEIGHT, A NEW SATELLITE TOOK TO THE SKIES.
"IMAGE" LIVED UP TO ITS NAME.
FOR THE FIRST TIME IT SENT BACK DYNAMIC PICTURES SHOWING EARTH AND THE SPACE WEATHER THAT SURROUNDS IT.
WITH ANTENNAS LONGER THAN THE EMPIRE STATE BUILDING IS TALL "IMAGE" HAS GIVEN US THE "BIG PICTURE" OF OUR PLANET, SWIMMING IN A SEA OF CHARGED PARTICLES.
AND NOT JUST STILLS... BUT MOVIES.
HERE, AN AURORA AT THE PEAK OF A SPACE STORM...
AND HERE'S WHAT'S CALLED A SUB-STORM SWEEPING AROUND THE OVAL WHICH INDICATES THE PRESENCE OF AN AURORA.
Barbara Thompson:
Now we have the instrumentation that will actually allow us to see this energy emerging below the surface of the Sun, being erupted from the Sun, and being transported through the solar wind, and finally being dumped on Earth, and then dissipated throughout the Earth's magnetosphere and atmosphere. And that's something that we've never been able to really see before.
FOR THE FIRST TIME IN HISTORY, WE NOW HAVE DRAMATIC REAL-TIME PICTURES OF WHAT IT'S LIKE TO BE A PLANET AND A SPECIES DEEPLY CONNECTED TO OUR SUN... A RELATIONSHIP SO CLOSE WE MIGHT CALL IT...
"LIVING WITH A STAR"...
