1 00:00:00,000 --> 00:00:12,734 (MUSIC) 2 00:00:12,767 --> 00:00:13,667 JOAN CARTAN-HANSEN: HI, I'M JOAN 3 00:00:13,667 --> 00:00:14,567 CARTAN-HANSEN. 4 00:00:14,567 --> 00:00:15,834 AND WELCOME TO SCIENCE TREK: THE 5 00:00:15,834 --> 00:00:16,734 WEB SHOW . 6 00:00:16,734 --> 00:00:17,901 AND WELCOME TO CRATERS OF THE 7 00:00:17,901 --> 00:00:19,033 MOON NATIONAL MONUMENT. 8 00:00:19,033 --> 00:00:20,234 AS RECENTLY AS 2,000 YEARS AGO 9 00:00:20,234 --> 00:00:21,501 THIS PLACE WAS ALIVE WITH ACTIVE 10 00:00:21,501 --> 00:00:23,501 VOLCANOS. 11 00:00:23,501 --> 00:00:24,634 JOINING US ARE TWO SCIENTISTS AT 12 00:00:24,634 --> 00:00:25,934 BOISE STATE UNIVERSITY JEFF 13 00:00:25,934 --> 00:00:28,133 JOHNSON AND BRITTANY BRAND. 14 00:00:28,133 --> 00:00:30,467 THANK YOU BOTH FOR JOINING US. 15 00:00:30,467 --> 00:00:31,667 BRITTANY BRAND: IT'S GREAT TO BE 16 00:00:31,667 --> 00:00:32,501 HERE. 17 00:00:32,501 --> 00:00:33,467 JEFF JOHNSON: THANKS FOR THE 18 00:00:33,467 --> 00:00:34,634 OPPORTUNITY. 19 00:00:34,634 --> 00:00:35,534 CARTAN-HANSEN: OKAY. 20 00:00:35,534 --> 00:00:36,701 LET'S GO TO YOUR QUESTIONS. 21 00:00:36,701 --> 00:00:39,501 (MUSIC) 22 00:00:40,868 --> 00:00:42,067 COLLINS: MY NAME IS COLLINS, AND 23 00:00:42,067 --> 00:00:43,267 I GO TO CYNTHIA MANN ELEMENTARY 24 00:00:43,267 --> 00:00:44,334 SCHOOL. 25 00:00:44,334 --> 00:00:47,067 AND MY QUESTION IS DO VOLCANOES 26 00:00:47,067 --> 00:00:50,467 ERUPT BECAUSE OF EARTHQUAKES? 27 00:00:50,467 --> 00:00:51,801 JOHNSON: SO VOLCANOES AND 28 00:00:51,801 --> 00:00:55,133 EARTHQUAKES LIVE SIDE BY SIDE. 29 00:00:55,133 --> 00:00:56,334 VOLCANOES WHEN THEY ARE GETTING 30 00:00:56,334 --> 00:00:57,734 READY TO ERUPT ALWAYS PRODUCE 31 00:00:57,734 --> 00:01:00,167 LITTLE EARTHQUAKES; SOMETIMES 32 00:01:00,167 --> 00:01:02,634 MEDIUMSIZED EARTHQUAKES. 33 00:01:02,634 --> 00:01:03,601 AND THIS IS A GOOD THING FOR 34 00:01:03,601 --> 00:01:04,667 PEOPLE WHO ARE INTERESTED IN 35 00:01:04,667 --> 00:01:05,834 TRYING TO FORECAST VOLCANIC 36 00:01:05,834 --> 00:01:07,667 ERUPTIONS, BECAUSE A VOLCANO 37 00:01:07,667 --> 00:01:09,100 THAT'S BECOMING RESTLESS WILL 38 00:01:09,100 --> 00:01:11,400 START TO SHAKE THE GROUND AS THE 39 00:01:11,400 --> 00:01:13,334 ROCK IS BROKEN AND THE MAGMA IS 40 00:01:13,334 --> 00:01:16,501 COMING TOWARDS THE SURFACE. 41 00:01:16,501 --> 00:01:17,834 DENNIS: HI, MY NAME IS DENNIS. 42 00:01:17,834 --> 00:01:18,901 I GO TO A.J. 43 00:01:18,901 --> 00:01:20,634 WINTERS ELEMENTARY. 44 00:01:20,634 --> 00:01:23,100 AND MY QUESTION IS WHAT CAUSES A 45 00:01:23,100 --> 00:01:27,033 VOLCANO TO ERUPT? 46 00:01:27,033 --> 00:01:28,501 BRAND: A VOLCANO WILL ERUPT WHEN 47 00:01:28,501 --> 00:01:30,133 MOLTEN MAGMA MAKES ITS WAY TO 48 00:01:30,133 --> 00:01:32,167 THE SURFACE. 49 00:01:32,167 --> 00:01:33,534 NOW, MAGMA IS WHAT WE CALL 50 00:01:33,534 --> 00:01:35,300 "MOLTEN ROCK" WHEN IT'S INSIDE 51 00:01:35,300 --> 00:01:37,667 THE GROUND; AND "LAVA" IS WHAT 52 00:01:37,667 --> 00:01:38,901 WE CALL IT WHEN IT ERUPTS 53 00:01:38,901 --> 00:01:40,534 OUTSIDE OF THE VOLCANO AND ONTO 54 00:01:40,534 --> 00:01:42,534 THE GROUND. 55 00:01:42,534 --> 00:01:44,467 MAGMA IS LIQUID, AND IT'S MOVING 56 00:01:44,467 --> 00:01:46,467 UP THROUGH ROCK, WHICH MEANS 57 00:01:46,467 --> 00:01:48,133 IT'S LESS DENSE, THIS LIQUID 58 00:01:48,133 --> 00:01:49,300 MAGMA IS LESS DENSE THAN THE 59 00:01:49,300 --> 00:01:51,300 SURROUNDING ROCK. 60 00:01:51,300 --> 00:01:52,434 WHEN YOU HAVE SOMETHING THAT'S 61 00:01:52,434 --> 00:01:53,601 LESS DENSE THAN WHAT'S AROUND 62 00:01:53,601 --> 00:01:54,634 IT, IT'S GOING TO RISE TOWARDS 63 00:01:54,634 --> 00:01:55,901 THE SURFACE, KIND OF LIKE A 64 00:01:55,901 --> 00:01:57,234 HOTAIR BALLOON RISING THROUGH 65 00:01:57,234 --> 00:01:59,634 COLD AIR. 66 00:01:59,634 --> 00:02:00,901 IN THE CASE OF MAGMA, WHEN IT 67 00:02:00,901 --> 00:02:02,033 MAKES ITS WAY TO THE SURFACE 68 00:02:02,033 --> 00:02:03,267 IT'S GOING TO START TO PUSH ON 69 00:02:03,267 --> 00:02:04,934 PUSH ON THE CRUST, AND THE 70 00:02:04,934 --> 00:02:06,434 PRESSURE INSIDE OF THAT MAGMA 71 00:02:06,434 --> 00:02:07,968 BODY WILL EVENTUALLY EXCEED THE 72 00:02:07,968 --> 00:02:11,734 PRESSURE OF THE ROCK HOLDING IT 73 00:02:11,734 --> 00:02:13,634 IN AND BREAK THROUGH TO ERUPT AT 74 00:02:13,634 --> 00:02:16,033 A VOLCANO. 75 00:02:16,033 --> 00:02:17,167 IT'S KIND OF LIKE FILLING UP A 76 00:02:17,167 --> 00:02:18,400 WATER BALLOON A LITTLE BIT TOO 77 00:02:18,400 --> 00:02:19,634 FULL AND THE WATER BALLOON 78 00:02:19,634 --> 00:02:22,000 BURSTING. 79 00:02:22,000 --> 00:02:23,033 THE SAME KIND OF PROCESS WITH 80 00:02:23,033 --> 00:02:24,167 MAGMA ERUPTING ONTO THE SURFACE 81 00:02:24,167 --> 00:02:26,434 AS LAVA. 82 00:02:26,434 --> 00:02:27,367 QUINN: HI, MY NAME IS QUINN, AND 83 00:02:27,367 --> 00:02:28,767 I GO TO GATEWAY ELEMENTARY. 84 00:02:28,767 --> 00:02:29,801 I WAS JUST WONDERING WHAT ARE 85 00:02:29,801 --> 00:02:31,400 THE KEY REASONS WHY SOME 86 00:02:31,400 --> 00:02:32,734 VOLCANOES STRONGLY AFFECT GLOBAL 87 00:02:32,734 --> 00:02:35,734 CLIMATE AND SOME DON'T? 88 00:02:35,734 --> 00:02:36,801 JOHNSON: SO THERE ARE TWO 89 00:02:36,801 --> 00:02:37,934 INGREDIENTS THAT ARE NECESSARY 90 00:02:37,934 --> 00:02:40,234 FOR A VOLCANO AND ITS ERUPTION 91 00:02:40,234 --> 00:02:42,767 TO AFFECT CLIMATE GLOBALLY. 92 00:02:42,767 --> 00:02:43,801 FIRST OF ALL, YOU NEED A BIG 93 00:02:43,801 --> 00:02:45,033 ERUPTION; YOU NEED TO SEND 94 00:02:45,033 --> 00:02:46,133 MATERIAL UP INTO THE 95 00:02:46,133 --> 00:02:47,300 STRATOSPHERE, WHICH IS MORE THAN 96 00:02:47,300 --> 00:02:49,834 6 MILES ABOVE SEA LEVEL. 97 00:02:49,834 --> 00:02:50,801 SECONDLY, YOU NEED TO ERUPT 98 00:02:50,801 --> 00:02:52,701 SULFUR GAS IN LARGE QUANTITIES 99 00:02:52,701 --> 00:02:54,934 SO THAT THAT SULFUR GAS REACTS 100 00:02:54,934 --> 00:02:56,834 WITH THE ATMOSPHERE AND CREATES 101 00:02:56,834 --> 00:02:59,133 SULFATE PARTICLES, WHICH 102 00:02:59,133 --> 00:03:01,801 EFFECTIVELY BLOCK SUNLIGHT FROM 103 00:03:01,801 --> 00:03:04,534 REACHING THE EARTH. 104 00:03:04,534 --> 00:03:05,701 CORTNEY: HI, MY NAME IS CORTNEY, 105 00:03:05,701 --> 00:03:06,901 AND I GO TO CYNTHIA MANN 106 00:03:06,901 --> 00:03:08,167 ELEMENTARY SCHOOL. 107 00:03:08,167 --> 00:03:09,634 AND MY QUESTION IS HOW LONG DOES 108 00:03:09,634 --> 00:03:11,567 IT TAKE UNTIL LAVA TURNS INTO 109 00:03:11,567 --> 00:03:13,934 ROCK? 110 00:03:13,934 --> 00:03:15,634 BRAND: WELL, IT REALLY DEPENDS. 111 00:03:15,634 --> 00:03:16,701 ONE THING TO KEEP IN MIND IS 112 00:03:16,701 --> 00:03:17,868 THAT WHEN LAVA ERUPTS ONTO THE 113 00:03:17,868 --> 00:03:19,467 SURFACE IT'S SO HOT THAT JUST 114 00:03:19,467 --> 00:03:21,701 INTERACTING WITH THE COOL AIR 115 00:03:21,701 --> 00:03:23,300 AROUND IT, THE SURFACE WILL COOL 116 00:03:23,300 --> 00:03:25,267 VERY QUICKLY MAYBE WITHIN 117 00:03:25,267 --> 00:03:26,934 MINUTES IT WILL FORM A CRUST 118 00:03:26,934 --> 00:03:28,300 THAT'S SOLID ENOUGH THAT YOU 119 00:03:28,300 --> 00:03:29,934 COULD ACTUALLY WALK ON IT, BUT 120 00:03:29,934 --> 00:03:31,968 IT MIGHT MELT YOUR BOOTS BECAUSE 121 00:03:31,968 --> 00:03:33,400 THERE'S STILL A LOT OF MOLTEN 122 00:03:33,400 --> 00:03:34,667 STUFF JUST UNDERNEATH THAT 123 00:03:34,667 --> 00:03:36,000 CRUST, WHICH IS GOING TO TAKE 124 00:03:36,000 --> 00:03:37,434 LONGER TO COOL. 125 00:03:37,434 --> 00:03:39,000 SO LAVA FLOWS IN HAWAII, FOR 126 00:03:39,000 --> 00:03:40,901 EXAMPLE, THE CRUST WILL COOL 127 00:03:40,901 --> 00:03:42,367 VERY QUICKLY, WITHIN MINUTES OF 128 00:03:42,367 --> 00:03:43,467 FLOWING ACROSS THE SURFACE, BUT 129 00:03:43,467 --> 00:03:45,167 THE CENTER MOLTEN PART CAN BE 130 00:03:45,167 --> 00:03:47,667 MOLTEN FOR QUITE A BIT LONGER. 131 00:03:47,667 --> 00:03:50,033 IN ANOTHER CASE, SOMETIMES 132 00:03:50,033 --> 00:03:52,100 VOLCANOES CAN GENERATE LAVA 133 00:03:52,100 --> 00:03:53,667 LAKES. 134 00:03:53,667 --> 00:03:54,767 AND THIS IS WHERE LAVA WILL 135 00:03:54,767 --> 00:03:56,100 ACTUALLY ERUPT OUT OF A VENT AND 136 00:03:56,100 --> 00:03:57,467 FILL IN THE CRATER OF A VOLCANO. 137 00:03:57,467 --> 00:04:00,033 IN THIS CASE, IF THE VOLCANO IS 138 00:04:00,033 --> 00:04:01,767 SHUT OFF AND THE LAVA IS SHUT 139 00:04:01,767 --> 00:04:04,334 OFF, THE CENTER OF THAT LAVA 140 00:04:04,334 --> 00:04:05,701 LAKE WILL TAKE A VERY LONG TIME 141 00:04:05,701 --> 00:04:07,834 TO COOL. 142 00:04:07,834 --> 00:04:08,968 SO A GOOD EXAMPLE OF THIS IS THE 143 00:04:08,968 --> 00:04:11,300 KILAUEA IKI ERUPTION IN HAWAII, 144 00:04:11,300 --> 00:04:13,167 WHICH WAS JUST A FLANK VENT FROM 145 00:04:13,167 --> 00:04:14,767 KILAUEA. 146 00:04:14,767 --> 00:04:16,100 IN THIS ERUPTION THERE WAS A 147 00:04:16,100 --> 00:04:17,334 LAVA LAKE THAT WAS 150 FEET 148 00:04:17,334 --> 00:04:19,033 THICK. 149 00:04:19,033 --> 00:04:20,434 THE CRUST COOLED IMMEDIATELY. 150 00:04:20,434 --> 00:04:21,667 THERE WERE VOLCANOLOGISTS 151 00:04:21,667 --> 00:04:22,734 WALKING ACROSS IT AND DRILLING 152 00:04:22,734 --> 00:04:23,934 DOWN TO TAP INTO THE LAVA AND 153 00:04:23,934 --> 00:04:26,200 GET SAMPLES. 154 00:04:26,200 --> 00:04:27,467 IT TOOK MORE THAN 30 YEARS FOR 155 00:04:27,467 --> 00:04:29,834 THAT LAVA INSIDE KILAUEA IKI'S 156 00:04:29,834 --> 00:04:33,667 LAVA LAKE TO COOL. 157 00:04:33,667 --> 00:04:35,067 ELSA: MY NAME IS ELSA, AND I GO 158 00:04:35,067 --> 00:04:37,033 TO LONGFELLOW ELEMENTARY. 159 00:04:37,033 --> 00:04:38,200 AND MY QUESTION IS WHAT IS THE 160 00:04:38,200 --> 00:04:41,868 BIGGEST ERUPTION EVER RECORDED? 161 00:04:41,868 --> 00:04:43,100 JOHNSON: ONE OF THE BIGGEST 162 00:04:43,100 --> 00:04:44,400 HISTORICAL ERUPTIONS THAT HAS 163 00:04:44,400 --> 00:04:48,067 OCCURRED DURING IN RECENT TIMES 164 00:04:48,067 --> 00:04:49,701 HAS BEEN THE ERUPTION OF TAMBORA 165 00:04:49,701 --> 00:04:51,968 VOLCANO IN INDONESIA, WHICH 166 00:04:51,968 --> 00:04:55,934 ERUPTED IN 1815 AND RELEASED 165 167 00:04:55,934 --> 00:05:01,234 CUBIC KILOMETERS OF MAGMA. 168 00:05:01,234 --> 00:05:02,801 HOW MUCH IS THAT? 169 00:05:02,801 --> 00:05:03,934 WELL, THAT WAS ABOUT 160 TIMES 170 00:05:03,934 --> 00:05:05,767 THE SIZE OF MOUNT ST. HELEN'S 171 00:05:05,767 --> 00:05:07,601 ERUPTION. 172 00:05:07,601 --> 00:05:09,167 THIS ERUPTED IN 1815, AND IT 173 00:05:09,167 --> 00:05:12,367 CAUSED LOTS OF LOSS OF LIFE. 174 00:05:12,367 --> 00:05:13,334 IT CHANGED THE CLIMATE OF THE 175 00:05:13,334 --> 00:05:14,868 PLANET, AND IT GENERATED OR 176 00:05:14,868 --> 00:05:16,501 PRODUCED A GIANT HOLE IN THE 177 00:05:16,501 --> 00:05:19,567 GROUND CALLED A CALDERA. 178 00:05:19,567 --> 00:05:20,667 TONY: HI, MY NAME IS TONY. 179 00:05:20,667 --> 00:05:21,667 AND I GO TO WHITE PINE 180 00:05:21,667 --> 00:05:23,000 ELEMENTARY. 181 00:05:23,000 --> 00:05:24,334 AND MY QUESTION IS WHICH VOLCANO 182 00:05:24,334 --> 00:05:25,701 IS MOST DANGEROUS, THE CINDER 183 00:05:25,701 --> 00:05:28,434 CONE, COMPOSITE VOLCANO, OR A 184 00:05:28,434 --> 00:05:31,934 SHIELD VOLCANO? 185 00:05:31,934 --> 00:05:32,934 BRAND: WHAT MAKES A VOLCANO 186 00:05:32,934 --> 00:05:34,400 DANGEROUS ISN'T NECESSARILY THE 187 00:05:34,400 --> 00:05:36,334 TYPE OF VOLCANO IT IS OR WHETHER 188 00:05:36,334 --> 00:05:38,067 OR NOT IT'S GOING TO HAVE A LAVA 189 00:05:38,067 --> 00:05:40,767 FLOW ERUPTION OR AN EXPLOSIVE 190 00:05:40,767 --> 00:05:43,000 ERUPTION THAT FORMS ASH. 191 00:05:43,000 --> 00:05:44,701 WHAT MAKES A VOLCANO DANGEROUS 192 00:05:44,701 --> 00:05:46,100 IS WHEN THERE ARE PEOPLE LIVING 193 00:05:46,100 --> 00:05:47,667 IN THE PATH OF POTENTIAL 194 00:05:47,667 --> 00:05:49,567 VOLCANIC HAZARDS. 195 00:05:49,567 --> 00:05:50,634 SO, FOR EXAMPLE, THE MOST 196 00:05:50,634 --> 00:05:51,901 DANGEROUS VOLCANO IN THE UNITED 197 00:05:51,901 --> 00:05:54,434 STATES IS MOUNT RAINIER. 198 00:05:54,434 --> 00:05:55,467 AND THAT'S BECAUSE THERE ARE 199 00:05:55,467 --> 00:05:56,701 HUNDREDS OF THOUSANDS OF PEOPLE 200 00:05:56,701 --> 00:05:57,868 LIVING ALONG THE FLANKS AND 201 00:05:57,868 --> 00:06:00,701 DOWNSTREAM FROM MOUNT RAINIER. 202 00:06:00,701 --> 00:06:02,133 ANOTHER VERY DANGEROUS VOLCANO, 203 00:06:02,133 --> 00:06:03,567 WORLDWIDE, IS MOUNT VESUVIUS, IN 204 00:06:03,567 --> 00:06:05,234 ITALY. 205 00:06:05,234 --> 00:06:06,334 MOUNT VESUVIUS IS FAMOUS FOR ITS 206 00:06:06,334 --> 00:06:08,534 79 AD ERUPTION WHICH TOOK OUT 207 00:06:08,534 --> 00:06:10,000 THE TOWNS OF HERCULANEUM AND 208 00:06:10,000 --> 00:06:11,901 POMPEII. 209 00:06:11,901 --> 00:06:12,968 THERE ARE CURRENTLY MORE THAN 210 00:06:12,968 --> 00:06:14,133 500,000 PEOPLE LIVING IN THAT 211 00:06:14,133 --> 00:06:16,834 ZONE. 212 00:06:16,834 --> 00:06:17,868 SO THOSE ARE CLEARLY VERY 213 00:06:17,868 --> 00:06:19,567 DANGEROUS, THESE STRATOVOLCANOES 214 00:06:19,567 --> 00:06:21,200 THAT ARE FAMOUS FOR PRODUCING 215 00:06:21,200 --> 00:06:22,868 VERY EXPLOSIVE ERUPTIONS WHERE 216 00:06:22,868 --> 00:06:24,467 ASH CANNOT ONLY GO UP INTO THE 217 00:06:24,467 --> 00:06:26,167 SKY BUT CAN COLLAPSE BACK DOWN 218 00:06:26,167 --> 00:06:27,834 TO FORM THESE GROUNDHUGGING 219 00:06:27,834 --> 00:06:30,000 CLOUDS OF ASH, GAS, AND ROCK 220 00:06:30,000 --> 00:06:32,834 THAT BURY LANDSCAPES. 221 00:06:32,834 --> 00:06:35,701 BUT A SHIELD VOLCANO OR A CINDER 222 00:06:35,701 --> 00:06:37,467 CONE COULD BE EQUALLY AS 223 00:06:37,467 --> 00:06:38,901 DANGEROUS IF THERE ARE PEOPLE IN 224 00:06:38,901 --> 00:06:40,868 THE PATH OF THE LAVA. 225 00:06:40,868 --> 00:06:42,067 SO, REALLY, IT DEPENDS ON 226 00:06:42,067 --> 00:06:44,534 WHETHER NOT WHETHER OR NOT A 227 00:06:44,534 --> 00:06:45,901 VOLCANO IS GOING TO ERUPT, BUT 228 00:06:45,901 --> 00:06:47,534 WHETHER OR NOT THERE ARE PEOPLE 229 00:06:47,534 --> 00:06:48,934 LIVING IN A ZONE THAT OVERLAPS 230 00:06:48,934 --> 00:06:50,901 WITH THE VOLCANIC HAZARDS WHEN 231 00:06:50,901 --> 00:06:53,434 THE VOLCANO ERUPTS. 232 00:06:53,434 --> 00:06:54,534 CARTAN-HANSEN: I'M SORRY, WE'VE 233 00:06:54,534 --> 00:06:55,767 RUN OUT OF TIME. 234 00:06:55,767 --> 00:06:56,901 MY THANKS TO JEFF AND BRITTANY 235 00:06:56,901 --> 00:06:58,267 FOR ANSWERING QUESTIONS. 236 00:06:58,267 --> 00:06:59,334 BRAND: THANK YOU FOR HAVING US. 237 00:06:59,334 --> 00:07:00,234 JOHNSON: YEAH. 238 00:07:00,234 --> 00:07:01,501 AND THANKS FOR THE GREAT 239 00:07:01,501 --> 00:07:02,634 QUESTIONS. 240 00:07:02,634 --> 00:07:03,801 CARTAN-HANSEN: AND THANKS, TOO, 241 00:07:03,801 --> 00:07:04,767 TO THE FOLKS AT BOISE STATE 242 00:07:04,767 --> 00:07:05,968 UNIVERSITY AND THE FOLKS HERE AT 243 00:07:05,968 --> 00:07:07,167 CRATERS OF THE MOON NATIONAL 244 00:07:07,167 --> 00:07:08,300 MONUMENT FOR HOSTING US. 245 00:07:08,300 --> 00:07:09,434 IF YOU WANT TO LEARN MORE, CHECK 246 00:07:09,434 --> 00:07:10,734 OUT THE VOLCANOES AREA ON THE 247 00:07:10,734 --> 00:07:11,968 SCIENCE TREK WEBSITE. 248 00:07:11,968 --> 00:07:13,400 YOU'LL FIND FACTS, LINKS, GAMES, 249 00:07:13,400 --> 00:07:15,234 OUR VOLCANOES BROADCAST SHOW, 250 00:07:15,234 --> 00:07:16,701 AND LOTS MORE. 251 00:07:16,701 --> 00:07:17,868 AND EVERY WEEK CHECK OUT MY BLOG 252 00:07:17,868 --> 00:07:19,234 FOR THE LATEST SCIENCE NEWS FOR 253 00:07:19,234 --> 00:07:20,601 KIDS. 254 00:07:20,601 --> 00:07:22,834 ALL AT IDAHOPTV.ORG. 255 00:07:22,834 --> 00:07:24,133 THANKS FOR JOINING US FOR 256 00:07:24,133 --> 00:07:27,100 SCIENCE TREK: THE WEB SHOW .