WEBVTT 00:11.277 --> 00:11.711 HIS. 00:11.711 --> 00:13.813 >>> HI, I'M JOAN CARTAN-HANSEN, AND WELCOME TO SCIENCE TREK THE 00:13.813 --> 00:16.082 WEB SHOW, AND JOINING ME TODAY TO ANSWER YOUR QUESTIONS ABOUT 00:16.082 --> 00:18.818 THE EARTH, ARE VIRGINIA GILLERMAN AND JEFFERY JOHNSON. 00:18.818 --> 00:20.120 THANK YOU BOTH FOR BEING HERE. 00:20.120 --> 00:21.888 I APPRECIATE YOU TAKING THE TIME. 00:21.888 --> 00:23.089 >> THANKS FOR INVITING US. 00:23.089 --> 00:23.723 >> THANK YOU. 00:23.723 --> 00:24.290 >> OK. 00:24.290 --> 00:32.399 LET'S GO TO YOUR QUESTIONS. 00:32.399 --> 00:34.668 >> SHILA WOULD LIKE TO KNOW WHY IS THE EARTH ROUND? 00:34.668 --> 00:39.105 >> WHEN THE EARTH FORMED, IT WAS A HOT GLOB OF MATERIAL. 00:39.105 --> 00:44.110 AND GRAVITY PULLED IT TOGETHER IN THE FORM THAT WAS MOST 00:44.110 --> 00:44.644 CONVENIENT. 00:44.644 --> 00:48.114 THEY COULD NOT PULL IT TOGETHER IN THE FORM OF A CUBE BECAUSE 00:48.114 --> 00:50.583 THAT WOULD BE UNNATURAL FOR THE GRAVITATIONAL FIELD. 00:50.583 --> 00:55.488 IT PULLED IT TOGETHER IN THE SHAPE OF A SPHERE, A SLIGHTLY 00:55.488 --> 01:00.527 DISTORTED SPHERE, BUT FOR, FOR MOST PURPOSES, A PERFECT SPHERE, 01:00.527 --> 01:06.700 THAT IS THE EASIEST SHAPE FOR GRAVITY TO PULL AN OBJECT INTO. 01:06.700 --> 01:12.238 >> I AM PURDUE, AND MY QUESTION IS -- HOW DO EARTHQUAKES WORK? 01:12.238 --> 01:16.976 >> EARTHQUAKES ARE WHEN ROCKS MOVE PAST EACH OTHER, AND THEY 01:16.976 --> 01:22.082 WILL FRACTURE, RELEASE ENERGY BY FRACTURING QUICKLY, AND JEFF 01:22.082 --> 01:23.016 WILL TELL US MORE. 01:23.016 --> 01:24.451 >> EARTHQUAKES HAPPEN WHEN ROCKS BREAK. 01:24.451 --> 01:27.554 ROCKS CAN BREAK ON VERY SMALL SCALES. 01:27.554 --> 01:30.724 IF YOU HAD, LET'S SAY, A ROCK THAT WAS THE SIZE OF A 01:30.724 --> 01:34.627 REFRIGERATOR, THAT ALL OF A SUDDEN BROKE, YOU WOULD HAVE A 01:34.627 --> 01:36.629 MAGNITUDE OF ONE EARTHQUAKE. 01:36.629 --> 01:40.734 NOW, IMAGINE YOU HAVE ROCK THAT EXTENDS FOR HUNDREDS OF MILES 01:40.734 --> 01:45.105 THAT BREAKS, YOU WOULD ALSO HAVE A VERY SIMILAR EARTHQUAKE, BUT 01:45.105 --> 01:47.273 IT WOULD BE MUCH, MUCH LARGER. 01:47.273 --> 01:52.212 IN BOTH CASES, SMALL AND LARGE, THE EARTH'S ROCKS ARE BREAKING. 01:52.212 --> 01:54.381 AND BREAKING FAST. 01:54.381 --> 01:58.418 >> DEBRA WOULD LIKE TO KNOW, IS THE EARTH THE ONLY PLANET WITH 01:58.418 --> 01:58.885 WATER? 01:58.885 --> 02:03.323 >> IT'S NOT THE ONLY PLANET WITH WATER, IT'S THE ONLY ONE THAT, 02:03.323 --> 02:06.860 THAT WE KNOW OF THAT, THAT HAS A, HAS ABUNDANT WATER, FOR 02:06.860 --> 02:10.697 EXAMPLE, ABOUT THREE QUARTERS OF OUR SURFACE IS COVERED WITH 02:10.697 --> 02:11.064 WATER. 02:11.064 --> 02:14.434 WE HAVE SOME EVIDENCE THAT ON A PLANET LIKE MARS, THERE WAS 02:14.434 --> 02:17.804 WATER IN THE PAST, OR THERE MIGHT BE WATER THAT'S BOUND UP 02:17.804 --> 02:23.076 WITH THE ROCKS OR FROZEN CARBON DIOXIDE. 02:23.076 --> 02:27.180 BUT, I DON'T THINK WE KNOW OF ANY OTHER PLANETS WITH ROTS OF 02:27.180 --> 02:30.283 LIQUID WATER ON THE SURFACE LIKE, LIKE THE EARTH HAS. 02:30.283 --> 02:31.351 BUT, WE'RE STILL LOOKING. 02:31.351 --> 02:35.288 THERE IS A LOT OF PLANETS, WE JUST DON'T KNOW THAT MUCH ABOUT. 02:35.288 --> 02:39.526 >> AND ONE EXCEPTION THAT I CAN THINK OF, IS UROPA, WHICH IS A 02:39.526 --> 02:43.730 MOON OF JUPITER, WHICH DOES HAVE PLENTY OF WATER ICE, AND MAYBE 02:43.730 --> 02:46.933 EVEN AN OCEAN BENEATH THAT WATER ICE. 02:46.933 --> 02:50.737 MOST OF MARS' WATER IS PROBABLY TIED UP RIGHT NOW IN ICE. 02:50.737 --> 02:54.274 NOT VERY USABLE FOR, FOR ANY SORTS OF LIFE THAT MAY, THAT MAY 02:54.274 --> 02:57.110 LIVE THERE. 02:57.110 --> 02:59.713 >> HI, I AM MIA. 02:59.713 --> 03:03.616 AND MY QUESTION IS, WHICH PART OF THE EARTH IS THE MOST 03:03.616 --> 03:06.319 IMPORTANT TO LIVE? 03:06.319 --> 03:08.988 >> I WOULD SAY THE SURFACE OF THE EARTH, THAT INCLUDES THE 03:08.988 --> 03:10.156 ROCKS THAT WE STAND ON. 03:10.156 --> 03:14.227 THE SOIL THAT'S PRODUCED FROM THOSE ROCKS, AND THE OCEANS, AND 03:14.227 --> 03:16.229 THE SPHERE THAT WE BREATHE. 03:16.229 --> 03:23.269 WE, ESSENTIALLY, LIVE AT, AT THE JUNCTION OF ALL OF THOSE VERY 03:23.269 --> 03:28.008 COMPLEX GEOCHEMICAL AND GEO LOGIC SYSTEMS. 03:28.008 --> 03:31.811 IT MIGHT BE THE DIVERSITY THAT HAS HELPED TO CREATE LIFE AND 03:31.811 --> 03:37.717 CREATED THE DELICATE BALANCE THAT WE USE IN OUR DAILY LIVES. 03:37.717 --> 03:44.357 >> SAM ASKS, WHERE DOES THE AIR COME FROM TO SUPPORT LIFE? 03:44.357 --> 03:48.528 >> SAM, THE AIR COMES FROM THE OXYGEN IN OUR AIR COMES FROM 03:48.528 --> 03:52.732 PHOTO SYNTHETIC PROCESSES, AND MOST OF THE OXYGEN THAT WE NEED 03:52.732 --> 03:58.004 AS HUMANS TO SURVIVE ON COMES AS A BY-PRODUCT, OR A POLLUTION 03:58.004 --> 04:00.140 FROM PLANT MATTER. 04:00.140 --> 04:05.078 SO, OXYGEN ORIGINALLY CAME FROM WATER AND CARBON DIOXIDE, WHICH 04:05.078 --> 04:10.684 WAS SPEWED OUT BY VOLCANOES OVER MANY, MANY EONS, AND PLANTS, 04:10.684 --> 04:13.720 TREES, BLUE-GREEN ALGAE AND OTHER VEGETATION TURNED THOSE 04:13.720 --> 04:17.424 RAW MATERIALS INTO THE OXYGEN THAT WE NEED. 04:17.424 --> 04:23.630 >> I AM SABRINA FROM HILLCRUST ELEMENTARY. 04:23.630 --> 04:27.000 HOW ARE DINOSAUR FOSSILS STILL UNDERI DON'T YOU UNDERSTAND? 04:27.000 --> 04:30.704 >> THEY ARE BECAUSE 24E6 NOT BEEN EROIDED OR WASHED DOWN FROM 04:30.704 --> 04:34.641 THE MOUNTAINTOPS OR WHEREVER THEY ARE FOUND YET. 04:34.641 --> 04:38.178 FOSSILS FORM UNDERGROUND, AND BACK WHEN THE DINOSAURS WERE 04:38.178 --> 04:40.714 STILL LIVING, AND THEY WOULD DIE. 04:40.714 --> 04:43.550 THEIR BONES WOULD FALL TO THE BOTTOM OF THE OCEAN. 04:43.550 --> 04:48.521 OR THE RIVER BOTTOM, WHEREVER THEY WERE LIVING. 04:48.521 --> 04:53.660 OVER TIME, THOSE BONES WOULD GET COVERED WITH DIRT, MUD, SAND, 04:53.660 --> 04:58.231 ETC., AND THOSE SEDIMENTS WOULD LIQUIFY, OR TURN INTO ROCK. 04:58.231 --> 05:03.303 AS THEY DO SO, ANY WATER THAT MIGHT HAVE SAY DISSOLVED SILICA 05:03.303 --> 05:10.477 IN IT, IE QUARTS, CAN PERCOLATE THROUGH THOSE, AND INTERACT WITH 05:10.477 --> 05:14.681 THOSE BONES, AND REPLACE THEM WITH FOSSILIZING MATERIAL. 05:14.681 --> 05:21.888 SO, THOSE FOSSILS ARE, ACTUALLY, FORMED UNDERGROUND. 05:21.888 --> 05:27.527 UNTIL THEY ARE EITHER FOUND BY A PALEONTOLOGIST OR A SCIENCE KID 05:27.527 --> 05:33.700 OUT FOR A NATURE HIKE, OR ERODED OFF, THEN THEY WILL REMAIN 05:33.700 --> 05:34.100 UNDERGROUND. 05:34.100 --> 05:39.072 >> I AM RYLEE, AND HOW DOES, HOW DO THE LAYERS OF THE SPHERE ALL 05:39.072 --> 05:39.539 CONNECT? 05:39.539 --> 05:42.008 >> HOW DO THE SPHERES OF THE EARTH CONNECT? 05:42.008 --> 05:44.544 THERE ARE A LOT OF SPHERE WORDS. 05:44.544 --> 05:47.814 THERE IS THE ATMOSPHERE, WHICH COMPRISES THE EARTH'S GASES, 05:47.814 --> 05:51.351 THERE IS THE HYDROSPHERE, WHICH IS THE EARTH'S OCEANS, THERE IS 05:51.351 --> 05:54.387 THE CRYOSPHERE, WHICH IS THE ICE CAPS. 05:54.387 --> 05:59.292 AND THEN BENEATH WE HAVE THE LITHOSPHERE, WHICH IS THE ROCKY 05:59.292 --> 06:02.762 OR RIGID PORTION OF THE EARTH THAT COMPRISES OUR TECTONIC 06:02.762 --> 06:03.129 PLATES. 06:03.129 --> 06:07.400 BEFORE THIS WE HAVE THE ESTHENOSPHERE, WHICH IS THE 06:07.400 --> 06:11.404 REGION ON TOP OF WHICH OUR TECTONIC PLATES FLOAT. 06:11.404 --> 06:16.976 >> AND UNDER THAT, YOU CONTINUE WITH THE MANTLE AND THE CORE, 06:16.976 --> 06:21.314 WHICH ARE OTHER SPHERICAL-SHAPED ROCKY OR MOLTEN ROCK REGIONS 06:21.314 --> 06:22.215 WITHIN THE EARTH. 06:22.215 --> 06:26.252 THEY JUST DON'T HAVE THE WORDS SPHERE IN THEM FOR SOME REASON. 06:26.252 --> 06:30.056 >> ALYSON WOULD LIKE TO KNOW, HOW DOES THE EARTH ROTATE? 06:30.056 --> 06:33.360 >> NOW, THE EARTH ROTATES BECAUSE IT'S ALWAYS ROTATED. 06:33.360 --> 06:36.162 THIS IS NOT A VERY SATISFACTORY ANSWER. 06:36.162 --> 06:40.166 BUT, WHEN THE EARTH WAS FORMED SOME 4.6 BILLION YEARS AGO, IT 06:40.166 --> 06:43.737 HAD SOMETHING WE CALL ANGULAR MOMENTUM ASSOCIATED WITH IT. 06:43.737 --> 06:47.907 THAT MEANS A TENDENCY TO SPIN, AND NOW, AS ALL OF THE PARTICLES 06:47.907 --> 06:52.078 IN OUR SOLAR SYSTEM ARE CREATED TO FORM PLANETS, IT ALL SORT OF 06:52.078 --> 06:55.648 CAME CLOSER TO THE SUN AND BEGAN TO SPIN FASTER. 06:55.648 --> 06:59.386 THINK OF AN ICE SKATER WITH HIS OR HER ARMS EXTENDED OUTWARD, 06:59.386 --> 07:02.956 AND AS THOSE ARMS COME IN CLOSER, THE ROTATION OR THE 07:02.956 --> 07:06.693 ANGULAR MOMENTUM IS CONSERVED BUT THE SPIN BECOMES FASTER. 07:06.693 --> 07:11.331 AND WE ARE SEEING THE RESULT OF THAT INITIAL ROTATION IN TODAY'S 07:11.331 --> 07:12.866 EARTH ROTATION. 07:12.866 --> 07:16.036 THE EARTH WILL CONTINUE TO ROTATE FOR A LONG, LONG TIME, 07:16.036 --> 07:20.340 UNLESS IT COLLIDES WITH SOME OTHER BODIES. 07:20.340 --> 07:24.611 >> LEXI WOULD LIKE TO KNOW, DO ALL PLANETS HAVE MOONS? 07:24.611 --> 07:27.947 >> NO, NOT ALL PLANETS HAVE MOONS. 07:27.947 --> 07:28.848 VENUS DOESN'T HAVE ANY. 07:28.848 --> 07:33.987 AND EARTH HAS ONE AND, AND SOME PLANETS, LIKE JUPITER AND SATURN 07:33.987 --> 07:36.056 HAVE MANY MOONS. 07:36.056 --> 07:38.358 SO, IT VARIES. 07:38.358 --> 07:41.261 >> BETSY WOULD LIKE TO KNOW, WHY IS THE EARTH NOT BEING STUCK 07:41.261 --> 07:43.329 INTO THE SUN? 07:43.329 --> 07:46.800 >> BETSY, THE EARTH IS ALWAYS FALLING TOWARDS THE SUN. 07:46.800 --> 07:50.870 BELIEVE IT OR NOT, THE SUN'S PULL OF GRAVITY CAUSES THE EARTH 07:50.870 --> 07:54.074 TO MOVE TOWARDS IT ALL THE TIME. 07:54.074 --> 07:57.377 BUT, I WOULD NOT LOSE ANY SLEEP OVER IT BECAUSE AT THE SAME 07:57.377 --> 08:00.213 TIME, THE EARTH HAS SOMETHING CALLED INERTIA. 08:00.213 --> 08:04.050 IT IS MOVING IT IN A DIRECTION THAT IS AWAY FROM THE SUN. 08:04.050 --> 08:07.654 SO, EVEN THOUGH THE EARTH IS CONTINUOUSLY FALLING TOWARDS THE 08:07.654 --> 08:12.459 SUN, IT IS MOVING AROUND THE SUN, AND ULTIMATELY, IT IS 08:12.459 --> 08:15.295 ORBITING IN A CIRCLE AROUND THE SUN. 08:15.295 --> 08:16.963 >> I'M SORRY BUT WE HAVE RUN OUT OF TIME. 08:16.963 --> 08:20.500 MY THANKS TO JEFF AND VIRGINIA FOR ANSWERING QUESTIONS TODAY. 08:20.500 --> 08:22.035 >> THANKS VERY MUCH FOR HAVING US. 08:22.035 --> 08:25.238 >> THANK YOU, AND THANK YOU TO THE STUDENTS WHO SUBMITTED GREAT 08:25.238 --> 08:26.673 QUESTIONS. 08:26.673 --> 08:29.709 THANKS, ALSO, TO THE FOLKS HERE AT BOISE STATE UNIVERSITY'S 08:29.709 --> 08:32.312 EARTH, SCIENCE, RESEARCH LAB FOR HOSTING US. 08:32.312 --> 08:35.682 IF YOU WANT TO LEARN MORE, CHECK OUT THE EARTH AREA ON THE 08:35.682 --> 08:36.316 SCIENCE TREK WEBSITE. 08:36.316 --> 08:40.053 YOU WILL FIND LINKS, GAMES, AND EARTH BROADCAST SHOWS, AND LOTS 08:40.053 --> 08:40.620 MORE. 08:40.620 --> 08:43.523 EVERY WEEK, CHECK OUT MY BLOG FOR THE LATEST SCIENCE NEWS FOR 08:43.523 --> 08:45.992 KIDS. 08:45.992 --> 08:46.860 ALL AT IDAHOPTV.ORG. 08:46.860 --> 08:52.699 THANKS FOR JOINING US FOR SCIENCE TREK, THE WEB SHOW.