WEBVTT 00:05.271 --> 00:06.639 >>> PRESENTATION OF SCIENCE TREK ON IDAHO PUBLIC TELEVISION IS 00:06.639 --> 00:09.542 MADE POSSIBLE THROUGH THE GENEROUS SUPPORT OF THE LAURA 00:09.542 --> 00:12.278 MOORE CUNNINGHAM FOUNDATION, COMMITTED TO FULFILLING THE 00:12.278 --> 00:18.184 MOORE FAMILY LEGACY OF BUILDING THE GREAT STATE OF IDAHO. 00:18.184 --> 00:22.088 >>> THE EARTH IS OUR HOME, BUT IT'S MADE UP OF MANY COMPLEX 00:22.088 --> 00:24.457 SYSTEMS WORKING TOGETHER TO KEEP US ALIVE. 00:24.457 --> 00:26.826 FIND OUT MORE ABOUT THE EARTH. 00:26.826 --> 00:30.563 STAY TUNED. 00:30.563 --> 00:40.206 SCIENCE TREK IS NEXT. 00:43.143 --> 00:45.311 >>> HI, I'M JOAN CARTAN-HANSEN, AND WELCOME TO SCIENCE TREK, AND 00:45.311 --> 00:47.747 WELCOME TO BOISE STATE UNIVERSITY'S EARTH, SCIENCE, 00:47.747 --> 00:48.648 RESEARCH LAB. 00:48.648 --> 00:51.051 WE'RE HERE TO ANSWER YOUR QUESTIONS ABOUT THE EARTH, BUT 00:51.051 --> 00:55.955 BEFORE WE DO, LET'S LEARN A BIT MORE. 00:55.955 --> 01:00.326 >> LET'S SEE IF WE CAN KEEP IT UP IN THE AIR, AND WHO FOR THE 01:00.326 --> 01:03.997 LONGEST. 01:03.997 --> 01:04.798 >> OK. 01:04.798 --> 01:09.803 >> DID YOU KNOW THE EARTH IS 93 MILLION MILES FROM THE SUN? 01:09.803 --> 01:12.906 THE EARTH IS THE THIRD PLANET FROM THE SUN. 01:12.906 --> 01:17.077 THE EARTH'S ORBIT IS MORE LIKE AN ELLIPSE RATHER THAN A PERFECT 01:17.077 --> 01:17.544 CIRCLE. 01:17.544 --> 01:21.348 THE EARTH SPINS ON AN AXIS, AND AN IMAGINARY LINE THAT GOES FROM 01:21.348 --> 01:23.450 POLE TO POLE. 01:23.450 --> 01:26.720 THE EARTH IS AT A TILT, IT'S THE TILT THAT GIVES US OUR SEASONS 01:26.720 --> 01:28.822 AS THE EARTH TRAVELS AROUND THE SUN. 01:28.822 --> 01:32.359 WHEN THE NORTHERN HEMISPHERE TILTS AWAY FROM THE SUN, YOU 01:32.359 --> 01:32.926 HAVE WINTER. 01:32.926 --> 01:36.830 AND AS THE NORTHERN HEMISPHERE TILTS TOWARDS THE SUN, WE GET 01:36.830 --> 01:37.197 SUMMER. 01:37.197 --> 01:40.667 AND BECAUSE THE EARTH IS SPINNING ON ITS AXIS, ONE SIDE 01:40.667 --> 01:45.038 OF THE PLANET FACES THE SUN AND THE OTHER IS IN THE SHAD OV, 01:45.038 --> 01:49.009 THAT'S WHAT GIVES US DAY AND NIGHT. 01:49.009 --> 01:53.580 >> DID YOU KNOW THAT OXYGEN ONLY MAKES UP 20% OF OUR AIR? 01:53.580 --> 01:57.951 >> THE EARTH IS COVERED BY A BLANKET OF GASES KNOWN AS THE 01:57.951 --> 01:58.351 SPHERE. 01:58.351 --> 02:01.888 THE TROPOSPHERE IS THE LOWEST LEVEL, THAT'S WHERE YOU WILL 02:01.888 --> 02:02.956 FIND THE AIR WE BREATHE. 02:02.956 --> 02:06.726 THE AIR IS 20% OXYGEN AND 70% NITROGEN, AND THE REST IS MADE 02:06.726 --> 02:07.894 UP OF OTHER GASES. 02:07.894 --> 02:12.432 ALL OF THE EARTH'S WEATHER HAPPENS IN THE TROPOSPHERE. 02:12.432 --> 02:15.235 THE NEXT LAYER IS THE STRATOSPHERE. 02:15.235 --> 02:18.805 THIS LAYER CONTAINS OZONE, A GAS THAT PROTECTS US FROM THE 02:18.805 --> 02:20.707 HARMFUL ULTRAVIOLET RAYS OF THE SUN. 02:20.707 --> 02:22.809 AFTER THAT, IS THE MESOSPHERE. 02:22.809 --> 02:26.346 THIS IS THE LAYER WHERE METEORITES USUALLY BURN UP FROM 02:26.346 --> 02:28.081 SPACE CREATING SHOOTING STARS. 02:28.081 --> 02:31.718 THEN THERE IS THE THERMO SPHERE, AND FINALLY THE EXOSPHERE. 02:31.718 --> 02:37.457 THIS IS THE OUTO MOST LAYER AT THE EDGE OF SPACE. 02:37.457 --> 02:39.025 >> LET ME PLAY! 02:39.025 --> 02:41.728 >> NO WAY. 02:41.728 --> 02:46.466 >> SO, DID YOU KNOW THAT THE EARTH'S CRUST IS ALWAYS MOVING? 02:46.466 --> 02:49.135 >> THE EARTH HAS FOUR MAIN LAYERS. 02:49.135 --> 02:52.472 AT THE CENTER IS AN EXTREMELY HOT CORE. 02:52.472 --> 02:54.908 THE CORE IS MADE UP OF TWO REGIONS. 02:54.908 --> 02:59.145 THE INNER CORE IS MADE UP OF SOLID, IRON, AND NICKEL. 02:59.145 --> 03:01.581 THE OUTER CORE IS MADE UP OF LIQUID IRON. 03:01.581 --> 03:04.951 THEY THINK THAT THE CIRCULATION OF THAT LIQUID CAUSES THE 03:04.951 --> 03:07.987 MAGNETIC FIELD AROUND THE EARTH. 03:07.987 --> 03:11.057 THE NEXT LAYER IS THE MANTLE, AND THEN THE OUTER LAYER, THE 03:11.057 --> 03:14.361 LAYER WE LIVE ON, IS KNOWN AS THE CRUST. 03:14.361 --> 03:18.431 THE CRUST IS ABOUT FOUR TO 40 MILES THICK AND MAKES UP LESS 03:18.431 --> 03:20.600 THAN 1% OF THE EARTH'S MASS. 03:20.600 --> 03:24.971 IT'S BROKEN UP INTO PIECES KNOWN AS TECTONIC PLATES. 03:24.971 --> 03:27.640 TECTONIC PLATES ARE PUSHED AND PULLED AROUND BY THE SLOW AND 03:27.640 --> 03:30.243 STEADY MOVEMENT OF THE UNDERLYING ROCK. 03:30.243 --> 03:34.647 AS THE PLATES MOVE, STRESSES BUILD UP. 03:34.647 --> 03:37.650 EARTHQUAKES HAPPEN WHEN THE STRESSES GROW BIG ENOUGH THAT 03:37.650 --> 03:42.255 THE PLATES SLIDE PAST ONE ANOTHER QUICKLY, AND WE FEEL 03:42.255 --> 03:43.923 THAT SHAKING. 03:43.923 --> 03:46.826 MOST VOLCANOS APPEAR ALONG PLATE BOUNDARIES. 03:46.826 --> 03:50.363 LOTS OF THINGS CAN CHANGE THE EARTH'S SURFACE. 03:50.363 --> 03:55.902 SOME HAPPENS QUICKLY FROM STRONG THINGS LIKE EARTHQUAKES AND 03:55.902 --> 03:56.369 VOLCANOES. 03:56.369 --> 03:58.672 OTHERS HAPPEN OVER PERIODS OF TIME BECAUSE OF PROCESSES LIKE 03:58.672 --> 04:01.041 EROSION FROM WIND OR WATER. 04:01.041 --> 04:04.611 YOU CAN SEE PATTERNS IN ROCK FORMATIONS AND FOSSILS IN ROCK 04:04.611 --> 04:08.515 LAYERS THAT SHOW CHANGES IN THE EARTH'S SURFACE OVER TIME. 04:08.515 --> 04:12.519 HUMANS CHANGE THE LOOK OF EARTH'S SURFACE, TOO. 04:12.519 --> 04:16.089 BUILDINGS, FARMS, AND MINES ARE A FEW WAYS WE HAVE CHANGED THE 04:16.089 --> 04:16.990 LOOK OF THE EARTH. 04:16.990 --> 04:21.628 DID YOU KNOW THAT MOST OF THE EARTH'S SURFACE IS COVERED WITH 04:21.628 --> 04:22.162 WATER? 04:22.162 --> 04:27.267 >> 70% OF THE EARTH'S SURFACE IS COVERED BY OCEAN. 04:27.267 --> 04:31.071 ONLY .008% OF THE EARTH'S FRESH WATER IS FOUND IN LAKES, RIVERS, 04:31.071 --> 04:32.539 AND STREAMS. 04:32.539 --> 04:35.608 THAT'S THE WATER THAT WE NEED TO LIVE. 04:35.608 --> 04:38.111 SO, WHEN YOU THINK ABOUT THE EARTH, THINK ABOUT THE SYSTEMS 04:38.111 --> 04:40.814 THAT MAKE UP THE PLANET. 04:40.814 --> 04:44.984 THE GEOSPHERE, THE SOIL, SEDIMENTS AND SOLID AND MOLTEN 04:44.984 --> 04:45.552 ROCK. 04:45.552 --> 04:47.921 THE HYDROSPHERE, THE WATER ON EARTH. 04:47.921 --> 04:53.093 THE ATMOSPHERE, THE LEVELS OF AIR AND GASES AROUND THE EARTH, 04:53.093 --> 05:00.667 AND THE BIOSPHERE, ALL THE ECO-SYSTEMS AND LIVING THINGS ON 05:00.667 --> 05:01.768 EARTH. 05:01.768 --> 05:04.137 >> THAT'S A LOT TO THINK ABOUT. 05:04.137 --> 05:05.772 >> PLEASE LET ME PLAY! 05:05.772 --> 05:09.576 >> YOU WILL GET YOUR, GO AND GET YOUR OWN BALL. 05:09.576 --> 05:09.943 >> OK. 05:09.943 --> 05:14.414 YOU ARE GOING TO PLAY THAT LOOKS LIKE THIS, I AM GOING TO PLAY 05:14.414 --> 05:20.053 WITH ONE THAT LOOKS LIKE THE SUN. 05:20.053 --> 05:21.421 >> WHAT IS THAT ALL ABOUT? 05:21.421 --> 05:27.260 YOU KNOW. 05:27.260 --> 05:30.630 >> AND JOINING ME NOW TO ANSWER YOUR QUESTIONS ABOUT THE EARTH 05:30.630 --> 05:33.733 ARE VIRGINIA GILLERMAN, A GEOLOGIST WITH THE IDAHO 05:33.733 --> 05:36.870 GEOLOGICAL SURVEY, AND JEFFERY JOHNSON, ASSISTANT RESEARCH 05:36.870 --> 05:39.272 PROFESSOR OF GEOPHYSICS AT BOISE STATE UNIVERSITY. 05:39.272 --> 05:40.807 THANK YOU FOR JOINING US. 05:40.807 --> 05:41.441 >> THANK YOU VERY MUCH. 05:41.441 --> 05:41.875 >> THANK YOU. 05:41.875 --> 05:42.909 >> THIS IS GOING TO BE FUN. 05:42.909 --> 05:49.449 >> LET'S GO TO YOUR QUESTIONS. 05:49.449 --> 05:54.554 >> HI, MY NAME IS JEFF, AND I GO TO KAMIAH ELEMENTARY SCHOOL IN 05:54.554 --> 05:58.024 KAMIAH, IDAHO, AND MY QUESTION IS -- WHAT MAKES THE EARTH 05:58.024 --> 05:58.658 ROTATE? 05:58.658 --> 06:02.228 >> THE EARTH ROTATES BECAUSE IT'S ALWAYS ROTATED, AND THAT'S, 06:02.228 --> 06:05.131 THAT'S REALLY A PRETTY POOR ANSWER. 06:05.131 --> 06:08.301 BUT, IT IS INTERESTING TO NOTE THAT THE EARTH IS ROTATING ABOUT 06:08.301 --> 06:12.972 THE SAME RATE THAT IT IS NOW, AS IT DID WHEN THE EARTH FORMED 06:12.972 --> 06:14.341 4.6 BILLION YEARS AGO. 06:14.341 --> 06:16.976 THE FACT OF THE MATTER IS, IT'S SPINNING LIKE A TOP, AND THERE 06:16.976 --> 06:20.613 IS NOTHING OUT THERE, NO FRICTION THAT'S SLOWING IT DOWN, 06:20.613 --> 06:24.150 AND IT WILL CONTINUE TO SPIN UNTIL THE EARTH MAY BE BILLIONS, 06:24.150 --> 06:27.420 TRILLIONS OF YEARS FROM NOW, IMPACTS WITH ANOTHER BODY. 06:27.420 --> 06:32.258 >> HI, I AM BILLY, AND I AM FROM [INAUDIBLE] CHARTER SCHOOL, AND 06:32.258 --> 06:35.328 MY QUESTION IS -- WHAT ARE TECTONIC PLATES? 06:35.328 --> 06:39.065 >> TECTONIC PLATES, BILLY, ARE WHAT GEOLOGISTS CALL THE RIGID 06:39.065 --> 06:45.805 LAYERS OF ROCK, WHICH FLOAT ON A HOTTER AND MORE FLUID 06:45.805 --> 06:49.876 SEMI-LIQUID ROCK UNDERNEATH. 06:49.876 --> 06:52.612 THE TECTONIC PLATES ARE CONSTANTLY IN MOTION, AND WHEN 06:52.612 --> 06:56.516 ONE OF THEM DIVES UNDER THE OTHER, LIKE ON, ON THE, THE 06:56.516 --> 07:00.687 EASTERN, OR WESTERN COAST OF SOUTH AMERICA, THEY CAN FORM 07:00.687 --> 07:05.658 MOUNTAIN RANGES LIKE THE ANDES AND VOLCANOES LIKE ECUADOR OR 07:05.658 --> 07:07.694 SIMILAR THINGS ARE HAPPENING IN JAPAN. 07:07.694 --> 07:11.831 SO, IT'S, IT'S THE BOUNDARIES BETWEEN THESE TECTONIC PLATES 07:11.831 --> 07:15.235 THAT CREATES SOME OF OUR MOST INTERESTING GEOLOGY. 07:15.235 --> 07:17.937 >> AND ONE OF THE COOL THINGS ABOUT TECTONIC PLATES IS JUST 07:17.937 --> 07:20.974 HOW FAST THAT THEY MOVE. 07:20.974 --> 07:24.411 TECTONIC PLATES ARE MOVING CONSTANTLY, BUT YOU AND I, WE 07:24.411 --> 07:25.145 CANNOT FEEL THEM. 07:25.145 --> 07:30.083 THEY MOVE AT THE SAME SPEED AS YOUR FINGERNAILS GROW. 07:30.083 --> 07:33.887 >> JAMISON WOULD LIKE TO KNOW, HOW BIG IS THE EARTH? 07:33.887 --> 07:41.261 >> THE EARTH HAS A RADIUS OF 6,371 KILOMETERS ON AVERAGE. 07:41.261 --> 07:44.798 THIS IS SOME 4,000 MILES IN TERMS OF THE RADIUS. 07:44.798 --> 07:46.332 HOW FAR IS THAT? 07:46.332 --> 07:50.737 THAT'S ABOUT THE DISTANCE FROM IDAHO TO NEW YORK AND BACK, AND 07:50.737 --> 07:52.806 SO IT'S A CONSIDERABLE SIZE. 07:52.806 --> 07:56.009 ONE THING THAT YOU MAY NOT BE AWARE OF IS THAT THE EARTH HAS A 07:56.009 --> 08:00.013 RADIUS THAT IS, THAT IS A LITTLE BIT BIGGER AT THE EQUATORS THAN 08:00.013 --> 08:05.485 AT THE POLES SO, OF THE EARTH AS BEING A SPHERE THAT'S SLIGHTLY 08:05.485 --> 08:05.952 SQUASHED. 08:05.952 --> 08:10.390 >> I AM ADDISON, AND MY QUESTION IS, WILL THE EARTH CONTINENTS 08:10.390 --> 08:11.591 EVER MEET AGAIN? 08:11.591 --> 08:14.494 >> THE EDGES OF THE CONTINENTS MEET, THEY MEET THE OCEAN 08:14.494 --> 08:20.033 PLATES, AND SOMETIMES, THEY MEET OTHER CONTINENTAL PLATES LIKE IN 08:20.033 --> 08:24.304 THE HIMALAYAS, BUT OVER THE LAST COUPLE OF BILLION YEARS, 08:24.304 --> 08:27.874 GEOLOGISTS ARE FINDING OUT, THE EARTH'S CONTINENTS AND PLATES 08:27.874 --> 08:31.678 HAVE MOVED TOGETHER AND THEN BEEN DRIVEN APART SEVERAL TIMES. 08:31.678 --> 08:39.085 SO, WE FORMED SUPER CONTINENTS LIKE RODINIA AND PANCIA, WHERE 08:39.085 --> 08:43.857 THE CONTINENTAL MASSES, THE LAND THAT YOU SEE THAT HAS ROCKS THAT 08:43.857 --> 08:49.796 HAVE MORE SILICON AND ALUMINUM AND SANDSTONE AREAS, THOSE 08:49.796 --> 08:55.001 CONTINENTAL AREAS HAVE BEEN PUSHED TOGETHER INTO THE SUPER 08:55.001 --> 08:59.439 COULD NOT NENTSZ, AND OVER TIME THOSE WILL BREAK APART AGAIN, 08:59.439 --> 09:01.574 SORT OF LIKE BILLIARD BALLS, YOU KNOW. 09:01.574 --> 09:04.911 HITTING EACH OTHER AND THEN BOUNCING OFF EACH OTHER. 09:04.911 --> 09:07.213 SO, THEY WILL MEET AGAIN, AND THEY WILL BREAK APART AGAIN. 09:07.213 --> 09:10.383 IT MAY TAKE A FEW MILLION YEARS. 09:10.383 --> 09:13.119 >> AND IN INDIA AND ASIA RIGHT NOW ARE COLLIDING WITH ONE 09:13.119 --> 09:16.656 ANOTHER, BUT IT'S A SLOW MOTION COLLISION. 09:16.656 --> 09:19.592 THOSE TWO CONTINENTS ARE COMING TOGETHER AT A RATE OF ONLY A FEW 09:19.592 --> 09:25.131 INCHES A YEAR, AND THEY ARE CAUSING THE CONTINUING UPLIFT IN 09:25.131 --> 09:27.867 GROWTH OF THE HIMALAYA MOUNTAINS. 09:27.867 --> 09:31.037 >> HARRIS WOULD LIKE TO KNOW, HOW WAS THE EARTH FORMED? 09:31.037 --> 09:35.975 >> HARRIS, THE EARTH WAS FORMED A LONG, LONG TIME AGO, 09:35.975 --> 09:42.482 4.6 BILLION YEARS AGO, THE EARTH ACCUMULATED FROM INTERSTELLAR 09:42.482 --> 09:46.152 GASES AND DEBRIS AND ACCUMULATED AND GREW INTO THE BLOB THAT WE 09:46.152 --> 09:48.254 LIVE ON TODAY. 09:48.254 --> 09:52.325 >> ALLEY WOULD LIKE TO KNOW, HOW DID GRAVITY GET TO EARTH AND WHO 09:52.325 --> 09:55.061 OR WHAT CREATED IT? 09:55.061 --> 09:58.631 >> GRAVITY IS A FUNDAMENTAL FORCE THAT EXISTS ANY TIME THAT 09:58.631 --> 10:00.700 YOU HAVE MASS. 10:00.700 --> 10:04.537 SO, WE HAVE GRAVITY ASSOCIATED WITH OUR OWN HUMAN BODIES, BUT 10:04.537 --> 10:07.907 THE EARTH'S MASS IS SO MUCH LARGER, THAT THE GRAVITATIONAL 10:07.907 --> 10:09.642 FORCE IS VERY MUCH NOTICEABLE. 10:09.642 --> 10:12.979 THIS IS WHY WE DON'T FLOAT OFF INTO SPACE. 10:12.979 --> 10:18.084 SO, WE HAVE GRAVITY BECAUSE THE EARTH IS VERY BIG AND MASSIVE. 10:18.084 --> 10:20.987 OTHER PLANETS ALSO HAVE GRAVITY, AND GRAVITY CAN EITHER BE 10:20.987 --> 10:24.557 GREATER OR SMALLER, DEPENDING UPON HOW BIG THE PLANETS ARE. 10:24.557 --> 10:27.460 SO, IF YOU LIVE ON ANOTHER PLANET THAT'S BIGGER, YOU WILL 10:27.460 --> 10:32.032 HAVE A GREATER FORCE OF GRAVITY, AND YOU WILL WEIGH HEAVIER. 10:32.032 --> 10:37.037 >> HI, I'M KELLEN, AND MY QUESTION IS -- WHAT PURPOSE DO 10:37.037 --> 10:39.673 THE LAYERS OF THE ATMOSPHERE SERVE? 10:39.673 --> 10:43.943 >> WELL, KELLEN, THE ATMOSPHERE IS REALLY CRITICAL FOR US HUMAN 10:43.943 --> 10:48.915 BEINGS BECAUSE IT PROVIDES THE OXYGEN THAT WE NEED TO BREATHE 10:48.915 --> 10:54.120 AND TO LIVE FROM, AND IT ALSO PROVIDES CARBON DIOXIDE, WHICH 10:54.120 --> 10:59.693 PLANTS BREATHE AND USE IN PHOTO SYNTHESIS, AND IT HAS OZONE, 10:59.693 --> 11:03.263 THAT HELP TO PROTECT US FROM THE SUN'S HARMFUL RADIATION. 11:03.263 --> 11:08.268 SO, WE WOULD NOT BE HERE WITHOUT THE ATMOSPHERE. 11:08.268 --> 11:11.237 >> I WAS GOING TO ADD THAT THE WEATHER IS HAPPENING IN OUR 11:11.237 --> 11:12.072 ATMOSPHERE, AS WELL. 11:12.072 --> 11:13.006 >> WEATHER, OF COURSE. 11:13.006 --> 11:20.647 THAT'S A REALLY IMPORTANT FUNCTION. 11:20.647 --> 11:25.185 >> YOU MAY FEEL LIKE YOU ARE STANDING STILL, BUT AS THE EARTH 11:25.185 --> 11:27.253 SPINS, YOU ARE MOVING FAST, DEPENDING ON WHERE YOU ARE ON 11:27.253 --> 11:30.256 THE GLOBE, YOU COULD BE SPINNING AT OVER 1,000 MILES PER HOUR, 11:30.256 --> 11:33.727 AND WE ALL TRAVEL AT 67,000 MILES PER HOUR AS THE EARTH 11:33.727 --> 11:40.934 MOVES AROUND THE SUN. 11:40.934 --> 11:45.005 >> HI, MY NAME IS ZOE, AND MY QUESTION IS -- HOW DOES THE 11:45.005 --> 11:47.540 EARTH'S ATMOSPHERE COMPARE TO OTHER PLANETS? 11:47.540 --> 11:50.577 >> EARTH'S ATMOSPHERE IS THE BEST ATMOSPHERE THAT WE KNOW OF 11:50.577 --> 11:52.679 FOR SUSTAINING LIFE. 11:52.679 --> 11:56.383 NOW, OTHER PLANETS WITHIN OUR SOLAR SYSTEM ALSO HAVE 11:56.383 --> 11:56.850 ATMOSPHERES. 11:56.850 --> 11:59.219 MOST OF THEM ARE MUCH, MUCH THINNER THAN THE EARTH'S 11:59.219 --> 12:01.988 ATMOSPHERE, AND NONE OF THEM HAVE OXYGEN, WHICH IS NECESSARY 12:01.988 --> 12:03.723 FOR LIFE. 12:03.723 --> 12:07.894 ONE OF THE SOLAR SYSTEMS PLANETS THAT HAS A THICK ATMOSPHERE IS 12:07.894 --> 12:11.598 VENUS, AND VENUS HAS LOTS AND LOTS OF CARBON DIOXIDE, AND AS 12:11.598 --> 12:16.436 FAR AS WE KNOW, THIS IS NOT A GAS THAT'S VERY GOOD FOR MOST 12:16.436 --> 12:20.273 TYPES OF LIFE FORMS. 12:20.273 --> 12:24.277 >> KYLE WOULD LIKE TO KNOW IS IT POSSIBLE TO LIVE ON ANOTHER 12:24.277 --> 12:24.744 PLANET? 12:24.744 --> 12:27.881 >> IT'S NOT POSSIBLE FOR HUMANS, LIKE WE ARE, TO LIVE ON ANY OF 12:27.881 --> 12:30.283 THE OTHER PLANETS THAT WE KNOW ABOUT. 12:30.283 --> 12:32.185 CERTAINLY NOT IN THIS SOLAR SYSTEM. 12:32.185 --> 12:35.822 THEY DON'T HAVE THE RIGHT AMOUNT OF OXYGEN IN THE ATMOSPHERE. 12:35.822 --> 12:37.557 SOME OF THEM ARE WAY TOO HOT. 12:37.557 --> 12:39.726 SEVERAL HUNDRED DEGREES EVERY DAY. 12:39.726 --> 12:41.561 OR WAY TOO COLD. 12:41.561 --> 12:46.733 AND, AND OUR LIFE, OUR, OUR HUMANS AND OUR ANIMALS AND OUR 12:46.733 --> 12:51.671 PLANTS HAVE EVOLVED UNDER THE SPECIAL CIRCUMSTANCES ON EARTH. 12:51.671 --> 12:56.576 SO, WITHOUT EXTRAORDINARY MEASURES AS IN A SPACE STATION 12:56.576 --> 12:59.212 OR SUITS, WE CANNOT LIVE ON OTHER PLANETS IN THE SOLAR 12:59.212 --> 13:01.047 SYSTEM. 13:01.047 --> 13:07.320 >> I AM INDY, AND MY QUESTION IS -- HOW DOES THE ATMOSPHERE KEEP 13:07.320 --> 13:08.688 IN OXYGEN? 13:08.688 --> 13:14.094 >> WELL, INDY, THE SPHERE HAS A VERY IMPORTANT ROLE IN KEEPING 13:14.094 --> 13:17.063 IN THE OXYGEN. 13:17.063 --> 13:21.701 SOME OF THAT IS DUE TO CARBON DIOXIDE AND OTHER GASES IN THE 13:21.701 --> 13:22.268 ATMOSPHERE. 13:22.268 --> 13:24.904 AND, AND I BELIEVE THAT SOME OF IT IS SIMPLY DUE TO GRAVITY 13:24.904 --> 13:29.442 BECAUSE GRAVITY STILL WOULD EXERT SOME PULL ON, ON EVEN 13:29.442 --> 13:32.178 GASES, IS THAT CORRECT, JEFF? 13:32.178 --> 13:34.981 >> GRAVITY, ULTIMATELY, KEEPS THE ATMOSPHERE NEXT TO THE 13:34.981 --> 13:39.085 EARTH, BUT, IT'S IMPORTANT TO NOTE THAT WE ARE LOSING OXYGEN 13:39.085 --> 13:42.822 TO, TO, DUE TO, DUE TO TRAVEL OUTSIDE OF OUR ATMOSPHERE. 13:42.822 --> 13:46.659 AND, AND AS WELL AS BY ABSORPTION OF OXYGEN IN OUR 13:46.659 --> 13:47.193 ROCKS. 13:47.193 --> 13:51.464 SO, THERE IS A CONSTANT BALANCE BETWEEN PRODUCTION OF OXYGEN 13:51.464 --> 13:58.038 FROM PLANTS AND LOSS OF OXYGEN DUE TO ESCAPE FROM THE PLANET, 13:58.038 --> 14:01.708 AS WELL AS THE PROCESSES WHICH LOCK UP THAT OXYGEN IN OUR 14:01.708 --> 14:02.208 ROCKS. 14:02.208 --> 14:02.976 >> AND HI. 14:02.976 --> 14:07.147 MY NAME IS CHLOE, AND I GO TO HILLCREST ELEMENTARY SCHOOL. 14:07.147 --> 14:10.250 HOW DOES THE VOLCANO SHOOT OUT LAVA? 14:10.250 --> 14:11.885 >> OH, I GET THIS ONE, CHLOE. 14:11.885 --> 14:16.256 I LOVE TO STUDY VOLCANOES, AND I STUDY HOW VOLCANOES PRODUCE LAVA 14:16.256 --> 14:20.093 AND HOW THAT LAVA GETS EJECTED FROM A VOLCANIC VENT. 14:20.093 --> 14:24.531 SO, REALLY, THERE IS ONE QUICK ANSWER, AND THAT IS VOLCANIC 14:24.531 --> 14:29.069 GASES DRIVE EXPLOSIONS, AND THOSE GASES CAN BE STEAM, CARBON 14:29.069 --> 14:32.706 DIOXIDE, OR SULFUR DIOXIDE, BUT PRESSURIZED GASES BLOW MATERIAL 14:32.706 --> 14:36.276 OUT OF A VOLCANIC VENT WITH MORE ENERGY AND MORE POWER THAN YOU 14:36.276 --> 14:38.244 CAN EVEN IMAGINE. 14:38.244 --> 14:44.718 >> MY NAME IS SOPHIE AND MY QUESTION IS, HOW DO HOT SPOTS 14:44.718 --> 14:45.285 MOVE? 14:45.285 --> 14:48.288 >> SOPHIE HOT SPOTS DON'T REALLY MOVE. 14:48.288 --> 14:53.026 IT'S, ACTUALLY, THE TECTONIC PLATES THAT MOVE OVER THE HOT 14:53.026 --> 14:56.262 SPOTS, SO A HOT SPOT LOOKS LIKE A PENCIL, THAT EXTENDS DEEP INTO 14:56.262 --> 14:57.030 THE EARTH. 14:57.030 --> 15:02.769 AND AS THE PLATE MOVES OVER IT, IT CREATES AN APPARENT HOT SPOT 15:02.769 --> 15:03.236 TRACK. 15:03.236 --> 15:09.609 AND FOR EXAMPLE, THE YELLOWSTONE HOT SPOT IS CURRENTLY UNDER 15:09.609 --> 15:11.611 YELLOWSTONE NATIONAL PARK. 15:11.611 --> 15:14.314 BUT 15 MILLION YEARS AGO, THE CONTINENT WAS SITUATED SUCH THAT 15:14.314 --> 15:18.585 HOT SPOT WAS ABOUT WHERE THE JUNCTION OF OREGON, IDAHO, AND 15:18.585 --> 15:20.520 NEVADA IS, IS TODAY. 15:20.520 --> 15:24.691 WE CAN TRACK THE MOVEMENT OF THE PLATE OVER THAT HOT SPOT BY 15:24.691 --> 15:29.262 LOOKING AT AGES OF ROCKS, THE PARTICULAR TYPE OF VOLCANIC 15:29.262 --> 15:33.066 ROCK, ALONG THAT, THAT, THAT HOT SPOT TRACK. 15:33.066 --> 15:39.739 >> HI, I AM OSCAR, AND I WAS WONDERING HOW COME YELLOWSTONE 15:39.739 --> 15:43.610 IS SO GEE LOGICALLY ACTIVE AND WHY THERE IS NO OTHER PLACE IN 15:43.610 --> 15:45.345 THE WORLD LIKE IT. 15:45.345 --> 15:48.448 >> YELLOWSTONE IS VERY ACTIVE. 15:48.448 --> 15:51.718 WE THINK IT'S ACTIVE BECAUSE WE CAN SEE IT TODAY. 15:51.718 --> 15:55.722 BUT, THERE ARE OTHER PLACES IN THE EARTH THAT ARE SIMILAR TO 15:55.722 --> 16:01.294 YELLOWSTONE THAT HAVE SIMILAR ROCKS, FOR EXAMPLE, THE, THE 16:01.294 --> 16:08.868 VOLCANIC ZONE IN NEW ZEALAND, WHICH IS ALSO UNDER LANE BY WHAT 16:08.868 --> 16:12.572 GEOLOGISTS WHERE THERE IS A LARGE MASS OF LIQUID ROCK OR 16:12.572 --> 16:16.976 MAGMA THAT IS HIGH IN SILICON AND ALUMINUM. 16:16.976 --> 16:21.881 AND, AND IN THAT CASE, ALSO, LIKE YELLOWSTONE, THE, THE HOT 16:21.881 --> 16:26.319 MAGMA CHAMBER HAS HEATED THE GROUNDWATER AND PRODUCED 16:26.319 --> 16:30.323 GEYSERS, HOT POOLS, MUD POTS, AND SIMILAR FEATURES THAT IF YOU 16:30.323 --> 16:34.794 VISIT NEW ZEALAND, YOU CAN WALK THROUGH. 16:34.794 --> 16:41.267 SO, YELLOWSTONE IS ONE OF THE PLACES THAT IS VOLCANOICALLY AND 16:41.267 --> 16:43.436 GEOTHEY REMEMBERALLY ACTIVE RIGHT NOW. 16:43.436 --> 16:45.605 THERE HAVE BEEN OTHER PLACES LIKE IT IN THE PAST, AND THERE 16:45.605 --> 16:50.610 IS A FEW OTHER PLACES LIKE IT IN THE WORLD TODAY. 16:50.610 --> 16:54.914 >> I JUST LIKE TO ADD THAT YELLOWSTONE IS SPECIAL IN THAT 16:54.914 --> 16:58.018 IT HAS THE MOST GEYSERS IN THE ENTIRE WORLD. 16:58.018 --> 17:02.956 IN FACT, 50% OF EARTH'S GEYSERS HAPPEN TO BE IN YELLOWSTONE. 17:02.956 --> 17:04.024 IT IS WONDERFUL. 17:04.024 --> 17:06.860 IT'S IN OUR BACKYARD, AND I AM VERY PROUD TO BE LIVING NOT SO 17:06.860 --> 17:14.567 FAR AWAY FROM YELLOWSTONE. 17:14.567 --> 17:17.604 >> THE FIELD OF STUDY THAT DEALS WITH THE REPRESENTATION AND 17:17.604 --> 17:21.975 MEASUREMENT OF THE EARTH IS GEOCITY. 17:21.975 --> 17:24.077 IT IS A SCIENCE THAT GOES WAY BACK. 17:24.077 --> 17:29.315 >> A LONG TIME AGO IN EGYPT, A MAN FIGURE OUT WHEN THE SUN WAS 17:29.315 --> 17:32.619 ABOVE ONE CITY, YOU COULD STAND AT A NEARBY CITY TO THE NORTH 17:32.619 --> 17:37.257 AND MEASURE THE ANGLE OF THE SHADOW SAYS AND MULTIPLY THAT BY 17:37.257 --> 17:39.626 THE DISTANCE TO GET THE DISTANCE AROUND THE ENTIRE EARTH. 17:39.626 --> 17:43.530 WITH THAT, THE SCIENCE OF GEODESY WAS BORN. 17:43.530 --> 17:45.899 IT DEALS WITH THE MEASUREMENT AND REPRESENTATION OF THE EARTH, 17:45.899 --> 17:49.336 OR TO PUT IT MORE SIMPLY, THE SCIENCE OF WHERE THINGS ARE AND 17:49.336 --> 17:51.971 JUST AS IMPORTANTLY, WHERE THEY HAVE BEEN AND WHERE THEY ARE 17:51.971 --> 17:53.006 GOING. 17:53.006 --> 17:56.443 6 THROUGH GEODESY, WE LEARN THE SIZE AND SHAPE OF THE EARTH, THE 17:56.443 --> 18:00.113 DIRECTION OF THE ROTATION, AND THE DISTANCE FROM THE SUN, AND 18:00.113 --> 18:02.315 MORE. 18:02.315 --> 18:05.752 WE THROUGH TRIANGULATION, WE CAN CREATE MAPS OF COUNTRIES, AND 18:05.752 --> 18:08.321 EVEN FIGURED OUT THE EARTH IS NOT A PERFECT SPHERE, AND AFTER 18:08.321 --> 18:11.958 SOME ARGUMENTS AND EXPEDITIONS TO PERU, WE MEASURED THAT IT'S 18:11.958 --> 18:13.927 JUST A BIT THICKER IN THE MIDDLE. 18:13.927 --> 18:18.498 BUILDING ON THIS INFORMATION, WE FOUND TONS OF PRACTICAL USES FOR 18:18.498 --> 18:19.032 GEODESY. 18:19.032 --> 18:22.502 USUALLY STARS AS A REFERENCE POINT, AND ACCURATE WATCHES, WE 18:22.502 --> 18:25.772 COULD RELIABLY DETERMINE LATITUDE AND LONGITUDE SO SHIPS 18:25.772 --> 18:27.774 COULD CROSS OCEANS TO GET TO WHERE THEY NEEDED. 18:27.774 --> 18:30.243 THE EXPLORERS VISITED UNCHARTERED REGIONS, AND MAPPED 18:30.243 --> 18:33.246 THEM AND FOUND THE TALLEST MOUNTAIN IN THE WORLD. 18:33.246 --> 18:37.584 LATER, ENGINEERS BUILT RAILROADS TO GET US TO THESE PLACES. 18:37.584 --> 18:40.687 WITH THE SAME REFERENCE SURFACE, RAIL TUNNELS COULD BE STARTED ON 18:40.687 --> 18:45.058 BOTH SIDES OF THE MOUNTAIN, AND SOMEHOW MEET IN THE MIDDLE. 18:45.058 --> 18:45.892 LIFE WAS GOOD. 18:45.892 --> 18:48.695 ONCE WE INVENTED RADIO TELESCOPES AND SATELLITES, 18:48.695 --> 18:49.629 THINGS GOT EVEN BETTER. 18:49.629 --> 18:52.632 WHEN SCIENTISTS USED A BUNCH OF SMALL RADIO DISHES LIKE ONE BIG 18:52.632 --> 18:56.870 ONE TO LOOK, SOMEBODY GOT THE IDEA YOU COULD USE THESE 18:56.870 --> 18:59.572 MEASUREMENTS TO DETERMINE VERY ACCURATELY THE DISTANCE BETWEEN 18:59.572 --> 19:03.376 THE TELESCOPES, AND NOW WE CAN LOOK AT THE MOVEMENT OF THE 19:03.376 --> 19:08.014 EARTH'S CHANGES, AND HOW THE EARTH TRAVELS ON ITS AXIS. 19:08.014 --> 19:10.450 SATELLITES BECAME VERY IMPORTANT BY ANALYZING THEIR ORBITS, WE 19:10.450 --> 19:14.554 CAN LEARN ABOUT OUR PLANET'S CHANGING SIZE AND SHAPE AND 19:14.554 --> 19:18.458 GRAVITY, AND BY MAKING LASER MEASUREMENTS, WE CAN LOOK AT 19:18.458 --> 19:21.461 CHANGES IN THE HEIGHT OF THE OCEANS AND ICE SHEETS TO HOW THE 19:21.461 --> 19:29.936 TIETH -- TIETS -- TIDES WORK, IS A GEODESY HAS A HUGE IMPACT ON 19:29.936 --> 19:32.405 OUR LIVES AND ALL BECAUSE SOMEBODY A LONG TIME AGO DECIDED 19:32.405 --> 19:38.778 TO LOOK DOWN A WELL. 19:38.778 --> 19:43.683 >> I AM FENA, AND MY QUESTION IS -- WHY WAS THERE VOLCANIC 19:43.683 --> 19:47.420 ACTIVITY IN IDAHO'S GEOLOGIC HISTORY BUT THERE ARE NOT ANY 19:47.420 --> 19:48.988 VOLCANOES IN IDAHO NOW? 19:48.988 --> 19:53.326 >> THERE HAVE BEEN PERIODS IN THE PAST, NOTABLY, ABOUT 19:53.326 --> 19:58.732 2 MILLION YEARS AGO, WHEN THE VOLCANOES OF THE SNAKE RIVER 19:58.732 --> 20:01.534 PLAIN WERE POPPING UP ALL OVER THE PLACE. 20:01.534 --> 20:06.706 15 MILLION YEARS AGO, WHEN THE COLUMBIA RIVER, BASALTS POURED 20:06.706 --> 20:09.642 OUT AND FLOWED TO THE PACIFIC OCEAN, AND ABOUT 45 MILLION 20:09.642 --> 20:14.547 YEARS AGO, WHEN THE CHALLIS VOLCANIC EPISODE OCCURRED. 20:14.547 --> 20:18.084 SO, THERE'S BEEN TIMES WHEN IT'S BEEN MUCH MORE ACTIVE THAN IT IS 20:18.084 --> 20:19.719 RIGHT NOW. 20:19.719 --> 20:20.820 BUT, YOU NEVER KNOW. 20:20.820 --> 20:24.524 MAYBE WE'LL GET A, A BIG VOLCANIC ERUPTION TOMORROW. 20:24.524 --> 20:28.194 >> YOU KNOW, I WOULD NOT LOSE SLEEP OVER THE IDEA OF A BIG 20:28.194 --> 20:29.662 VOLCANIC ERUPTION TOMORROW. 20:29.662 --> 20:34.100 BUT, IT IS IMPORTANT TO NOTE THAT IDAHO DOES HAVE RECENT 20:34.100 --> 20:38.004 VOLCANIC ACTIVITY, AS EARLY AS, AS RECENT AS 2000 YEARS AGO, 20:38.004 --> 20:42.042 THERE WERE LAVAS THAT ERUPTED FROM CRATERS OF THE MOON 20:42.042 --> 20:45.745 NATIONAL MONUMENT THAT HAS VERY, VERY FRESH LAVA FLOWS. 20:45.745 --> 20:49.916 AND 2000 YEARS AGO IS REALLY A BLINK OF THE EYE IN TERMS OF THE 20:49.916 --> 20:52.485 GEOLOGIC HISTORY. 20:52.485 --> 20:55.855 >> GABBY WOULD LIKE TO KNOW HOW DO WE GET EARTHQUAKES? 20:55.855 --> 20:59.526 >> EARTHQUAKES HAPPEN WHEN ROCKS BREAK VERY, VERY QUICKLY. 20:59.526 --> 21:03.630 WHEN THAT HAPPENS, THE EARTH MOVES VERY RAPIDLY, AND 21:03.630 --> 21:07.100 GENERATES SEISMIC WAVES, WHICH WE CAN RECORD WITH, WITH 21:07.100 --> 21:13.073 DELICATE AND HIGH FIDELITY INSTRUMENTATION CALLED 21:13.073 --> 21:13.606 SIZEOMETERS. 21:13.606 --> 21:15.542 THAT IS NOTHING MORE THAN AN INSTRUMENT THAT RECORDS THE 21:15.542 --> 21:20.447 SHAKING OF THE GROUND WITH MUCH MORE SENSITIVITY THAN HUMANS 21:20.447 --> 21:20.814 CAN. 21:20.814 --> 21:26.619 >> I AM AALIYAH AND I HAVE A QUESTION, WHY DOES CALIFORNIA 21:26.619 --> 21:28.822 HAVE SO MANY EARTHQUAKES AND IDAHO HAS SO FEW. 21:28.822 --> 21:31.891 >> YOU ARE ASKING WHY DOES IDAHO NOT HAVE MANNY EARTHQUAKES AS 21:31.891 --> 21:32.525 CALIFORNIA. 21:32.525 --> 21:37.297 IT'S FOR THE SIMPLE REASON THAT IDAHO IS LOCATED IN THE INTERIOR 21:37.297 --> 21:39.366 OF A CONTINENT. 21:39.366 --> 21:43.103 CALIFORNIA IS RIGHT ON THE VERY EDGE OF WHERE NORTH AMERICA AND 21:43.103 --> 21:44.738 PACIFIC TECTONIC PLATES MEET. 21:44.738 --> 21:48.742 AND IT JUST SO HAPPENS THAT MOST OF EARTH'S EARTHQUAKES HAPPEN 21:48.742 --> 21:50.310 ALONG THESE BOUNDARIES. 21:50.310 --> 21:55.048 THAT IS NOT TO SAY THAT IDAHO DOESN'T HAVE ANY EARTHQUAKES OR 21:55.048 --> 21:57.550 WON'T HAVE EARTHQUAKES IN THE FUTURE, BUT THE NUMBER OF 21:57.550 --> 22:01.888 EARTHQUAKES IN IDAHO IS FAR LESS THAN IT IS IN, SAY, CALIFORNIA, 22:01.888 --> 22:05.325 AND THE SIZE OF THE EARTHQUAKES THAT OCCUR HERE, ARE GENERALLY 22:05.325 --> 22:06.326 MUCH SMALLER. 22:06.326 --> 22:10.363 THE MOST RECENT, LARGEST EARTHQUAKES TO HAVE OCCURRED IN 22:10.363 --> 22:14.000 IDAHO HAPPENED IN 1983. 22:14.000 --> 22:16.970 AND IT WAS A MAGNITUDE OF 7.3 EARTHQUAKE. 22:16.970 --> 22:21.274 BUT THEY HAPPEN VERY INFREQUENTLY. 22:21.274 --> 22:25.912 >> CARA ASKS, WHY DOES THE EARTH MOVE BUT WE DON'T FEEL IT MOVE? 22:25.912 --> 22:30.116 >> THE EARTH MOVES, AND IT MOVES OVER ALL SORTS OF TIME SCALES, 22:30.116 --> 22:33.653 AND IT MOVES IN VERY INTERESTING FASHIONS. 22:33.653 --> 22:37.023 WE DO EXPERIENCE EARTH MOVEMENTS WHEN EARTHQUAKES OCCUR, AND THAT 22:37.023 --> 22:41.928 IS WHEN, WHEN SUDDEN BREAKAGE OF ROCKS CAUSE A SEISMIC WAVE TO 22:41.928 --> 22:47.934 PROPGATE AND SHAKE IT, BUILDINGS CAN BE KNOCKED OVER, AND THOSE 22:47.934 --> 22:49.736 MOVEMENTS CAN BE VERY, VERY INTENSE. 22:49.736 --> 22:55.308 NOW, THE EARTH ALSO MOVES VERY SLOWLY DUE TO PLATE TECTONIC 22:55.308 --> 22:55.675 MOVEMENTS. 22:55.675 --> 22:59.579 THOSE MOVEMENTS ARE SO VERY SLOW, THAT MOST OF US WILL NEVER 22:59.579 --> 23:00.613 SENSE THEM. 23:00.613 --> 23:05.051 THOSE PLATE TECTONIC MOVEMENTS OCCUR AT RATES OF ONLY A FEW 23:05.051 --> 23:06.486 INCHES PER YEAR. 23:06.486 --> 23:08.688 VERY, VERY SLOW. 23:08.688 --> 23:12.792 >> AND, OF COURSE, THE EARTH IS MOVING, SIMPLY BY ROTATING EACH 23:12.792 --> 23:13.526 DAY. 23:13.526 --> 23:18.164 BUT, IT HAPPENS ON SUCH A LARGE MASS, AND AT SUCH A, A SLOW RATE 23:18.164 --> 23:20.900 THAT WE DON'T FEEL IT. 23:20.900 --> 23:25.905 >> HI, I AM JENNA, AND I AM PART OF ANSWER -- ANTHONY CHARTER 23:25.905 --> 23:29.242 SCHOOL, AND MY QUESTION IS WHY IS THE SKY BLUE? 23:29.242 --> 23:32.012 >> THE SKY IS THE BLUE BECAUSE THE SUN WHEN RADIATES OUR 23:32.012 --> 23:36.349 SUNLIGHT IN THE FORM OF LIGHT, WHICH COMPRISES ALL COLORS OF 23:36.349 --> 23:41.087 THE RAINBOW, INTERACTS WITH THE SPHERE. 23:41.087 --> 23:44.524 OUR ATMOSPHERE HAS OXYGEN IN IT WHEN SCATTERS THE BLUE PORTION 23:44.524 --> 23:48.261 OF THE VISIBLE LIGHT, AND THAT THAT SCATTERED ENERGY COMES 23:48.261 --> 23:50.897 DOWN, AND WE CAN SEE IT WITH OUR EYES. 23:50.897 --> 23:55.201 IF YOU WERE TO LOOK AT THE SUN OUTSIDE OF THE SPHERE, IT WOULD 23:55.201 --> 23:56.636 LOOK WHITE. 23:56.636 --> 23:59.939 >> DEVON ASKS, HOW DID THE EARTH GET ITS NAME? 23:59.939 --> 24:02.308 >> I HAD TO LOOK THIS ONE UP. 24:02.308 --> 24:08.415 AND FROM WHAT I COULD READ, THE NAME COMES FROM AN OLD ENGLISH 24:08.415 --> 24:15.355 WORD, CLOSE TO EARTHA, I'M NOT SURE I'M PRONOUNCING IT RIGHT, 24:15.355 --> 24:20.994 BUT THE TERM GOES BACK AT LEAST OVER 1,000 YEARS, PROBABLY AT 24:20.994 --> 24:25.598 LEAST 1500 YEARS THAT WE CAN TRACE IT THROUGH THE LANGUAGES, 24:25.598 --> 24:30.804 INCLUDING OLD AND MIDDLE ENGLISH FROM SIMILAR SOUNDING WORDS. 24:30.804 --> 24:37.911 THERE WAS, I BELIEVE, A, A MYTHOLOGICAL GOD OF THE EARTH, 24:37.911 --> 24:41.915 WITH A SOMEWHAT SIMILAR NAME, BUT, EARLIER THAN THAT, I'M NOT 24:41.915 --> 24:42.549 REAL SURE. 24:42.549 --> 24:46.186 IT IS A GOOD QUESTION FOR A LINGUISTICS' EXPERT. 24:46.186 --> 24:50.123 >> AND THE EARTH IS, INDEED, THE ONLY PLANET IN THE SOLAR SYSTEM 24:50.123 --> 24:57.030 THAT HAS A NAME THAT DOES NOT COME FROM GREEK OR ROMAN 24:57.030 --> 24:57.530 MYTHOLOGY. 24:57.530 --> 25:01.835 >> MY QUESTION IS, HOW DOES THE MAGNETIC FIELD CHANGE FROM NORTH 25:01.835 --> 25:02.502 TO SOUTH? 25:02.502 --> 25:05.505 >> THIS QUESTION IS A FUNDAMENTALLY IMPORTANT QUESTION 25:05.505 --> 25:08.608 FOR WHICH THERE IS NO CONSENSUS ANSWER. 25:08.608 --> 25:12.879 WHAT WE DO KNOW IS THAT THE EARTH'S MAGNETIC FIELD REVERSES 25:12.879 --> 25:13.613 ITSELF. 25:13.613 --> 25:17.684 LAST REVERSED ITSELF 700,000 YEARS AGO, AND WHEN THIS 25:17.684 --> 25:24.057 HAPPENS, COMPASS DIRECTIONS WILL SLIP FROM NORTH TO SOUTH, AND 25:24.057 --> 25:27.427 THE MAY GETTIZATION WILL CHANGE OF THE EARTH, SUCH THAT MOLTEN 25:27.427 --> 25:31.331 ROCKS WHICH FREEZE CAN RECORD THE HISTORY OF THE EARTH'S 25:31.331 --> 25:36.269 MAGNIFICENTIC -- MAGNITUDIC FIELD, AND THIS IS HOW WE KNOW 25:36.269 --> 25:39.739 ABOUT THE BLAST TAKE TECTONIC MOVEMENTS, AND WE CAN RECORD THE 25:39.739 --> 25:41.975 CHANGING EARTH'S MAGNETIC FIELD. 25:41.975 --> 25:44.911 >> VIRGINIA, BEFORE WE RUN OUT OF TIME LET ME ASK YOU, WHY DID 25:44.911 --> 25:47.347 YOU PICK A JOB THAT DEALS WITH GEOLOGY? 25:47.347 --> 25:49.349 >> I JUST LIKE ROCKS. 25:49.349 --> 25:51.718 I LIKE BEING OUTDOORS. 25:51.718 --> 25:54.654 AND I LIKE USING MY MIND IN SOLVING PROBLEMS. 25:54.654 --> 25:59.459 AND I FOUND THAT GEOLOGY WAS A PLACE WHERE I COULD BE OUTDOORS, 25:59.459 --> 26:04.864 AND I COULD OBSERVE THINGS, AND I WAS USING MY MIND AT THE SAME 26:04.864 --> 26:07.667 TIME THAT I WAS ENJOYING BEING OUTDOORS. 26:07.667 --> 26:09.235 SO, I JUST LIKED IT. 26:09.235 --> 26:12.505 AND I'M LUCKY THAT I FOUND A JOB WHERE I CAN, ACTUALLY, GET PAID 26:12.505 --> 26:15.041 FOR DOING GEOLOGY. 26:15.041 --> 26:17.310 >> JEFF, IF SOMEONE IS INTERESTED IN FINDING A JOB IN 26:17.310 --> 26:20.980 EARTH SCIENCE, WHAT SHOULD HE OR SHE STUDY IN SCHOOL? 26:20.980 --> 26:24.484 >> SCIENCE IS ONE OF THE CAREERS THAT IS JUST SO EXCITING FOR A 26:24.484 --> 26:27.420 NUMBER OF REASONS. 26:27.420 --> 26:31.524 YOU HAVE ENTIRE FREEDOM TO EXPLORE NEW AREAS OF RESEARCH 26:31.524 --> 26:34.227 THAT NO ONE ELSE KNOWS ABOUT. 26:34.227 --> 26:39.532 IN ORDER TO BECOME A SCIENTIST, THE BEST SKILLS TO LEARN IN 26:39.532 --> 26:43.903 SCHOOL ARE ALL SKILLS, INCLUDING MATH, INCLUDING SCIENCE, AND 26:43.903 --> 26:46.606 BELIEVE IT OR NOT, INCLUDING WRITING SKILLS. 26:46.606 --> 26:50.443 EVEN SCIENTISTS, WHO ARE THE MARTYRS IN TERMS OF THE MATH AND 26:50.443 --> 26:54.714 SCIENCE, NEED TO BE ABLE TO CONVEY THEIR IDEAS TO OTHER 26:54.714 --> 26:57.917 PEOPLE AND TELL THEIR STORY TO THE WORLD. 26:57.917 --> 27:00.754 >> THANK YOU, VIRGINIA AND JEFF FOR ANSWERING QUESTIONS. 27:00.754 --> 27:02.455 I APPRECIATE YOU TAKING THE TIME TODAY. 27:02.455 --> 27:05.025 >> THANK YOU, JOAN AND TO ALL THE STUDENTS WHO SUBMITTED GREAT 27:05.025 --> 27:06.126 QUESTIONS TODAY. 27:06.126 --> 27:06.960 >> GREAT QUESTIONS. 27:06.960 --> 27:08.395 KEEP STUDYING SCIENCE. 27:08.395 --> 27:09.129 >> YES. 27:09.129 --> 27:11.865 >> OUR THANKS, ALSO, TO THE FOLKS HERE AT BOISE STATE 27:11.865 --> 27:14.401 UNIVERSITY'S EARTH SCIENCE RESEARCH LAB FOR HOSTING US. 27:14.401 --> 27:17.237 YOU CAN LEARN LOTS MORE ABOUT THE EARTH AND LOTS OF OTHER 27:17.237 --> 27:20.206 SCIENCE TOPICS ON THE SCIENCE TREK WEBSITE. 27:20.206 --> 27:23.877 WE'LL ANSWER MORE QUESTIONS ABOUT THE EARTH ON SCIENCE TREK 27:23.877 --> 27:24.611 THE WEB SHOW. 27:24.611 --> 27:27.981 IF YOU WANT TO SUBMIT A QUESTION FOR SCIENCE TREK, IT'S EASY. 27:27.981 --> 27:30.150 YOU AND YOUR CLASS CAN WIN PRIZES. 27:30.150 --> 27:34.254 YOU CAN SEND US AN EMAIL OR A VIDEO QUESTION AND RECORD IT ON 27:34.254 --> 27:37.424 YOUR WEB CAM OR CELL PHONE, AND IF YOU ARE AN EDUCATOR, WE'LL 27:37.424 --> 27:38.525 LEND YOU A CAMERA. 27:38.525 --> 27:42.529 THE LAST PRIZE WINNER WAS DILLON IN MRS. JACOB'S CLASS AT KAMIAH 27:42.529 --> 27:43.229 ELEMENTARY. 27:43.229 --> 27:46.166 SO TO FIND OUT ABOUT THE EARTH AND HOW TO SEND IN QUESTIONS AND 27:46.166 --> 27:48.435 WIN, GO TO THE SCIENCE TREK WEBSITE. 27:48.435 --> 27:51.905 EACH WEEK, CHECK OUT MY BLOG FOR THE LATEST SCIENCE NEWS FOR 27:51.905 --> 27:52.272 KIDS. 27:52.272 --> 27:56.443 YOU WILL FIND IT ALL AT IDAHOPV.ORG/SCIENCETREK. 27:56.443 --> 27:57.744 THANKS FOR JOINING US. 27:57.744 --> 28:02.182 WE'LL SEE YOU NEXT TIME ON SCIENCE TREK. 28:22.602 --> 28:24.137 >>> PRESENTATION OF SOIRG ON IDAHO PUBLIC TELEVISION IS MADE 28:24.137 --> 28:27.240 POSSIBLE THROUGH THE GENEROUS SUPPORT OF THE LAURA MOORE 28:27.240 --> 28:29.042 CUNNINGHAM FOUNDATION. 28:29.042 --> 28:32.078 COMMITTED TO FULFILLING THE MOORE FAMILY LEGACY OF BUILDING 28:32.078 --> 28:37.851 THE GREAT STATE OF IDAHO. 28:37.851 --> 28:40.720 >>> IF YOU WANT TO LEARN MORE ABOUT THIS TOPIC OR WATCH OUR 28:40.720 --> 28:44.357 VIDEOS, CHECK OUT THE SCIENCE TREK WEBSITE AT