1 00:00:00,020 --> 00:00:04,020 [slate] 2 00:00:04,040 --> 00:00:08,040 [slate] 3 00:00:08,060 --> 00:00:12,070 [slate] 4 00:00:12,090 --> 00:00:16,140 5 00:00:16,160 --> 00:00:20,220 So on August 21st of this year, the moon, sun and Earth 6 00:00:20,240 --> 00:00:24,360 will line up just perfectly so that the moon 7 00:00:24,380 --> 00:00:28,480 comes between the Earth and the sun and casts its shadow 8 00:00:28,500 --> 00:00:32,510 down onto the United States. And 9 00:00:32,530 --> 00:00:36,610 starting in Oregon, the core of its shadow 10 00:00:36,630 --> 00:00:40,740 called the umbra is going to travel across the U.S. in about 11 00:00:40,760 --> 00:00:44,930 1,500 miles per hour ending in South Carolina 12 00:00:44,950 --> 00:00:49,020 and everyone in North America, Central America and 13 00:00:49,040 --> 00:00:53,120 a good portion of South America are going to also experience a partial 14 00:00:53,140 --> 00:00:57,250 solar eclipse. And if you happen to be in that 70 mile 15 00:00:57,270 --> 00:01:01,380 wide path we just saw then you'll get to experience a total 16 00:01:01,400 --> 00:01:05,450 solar eclipse where the moon completely blocks out the bright solar 17 00:01:05,470 --> 00:01:09,500 disk allowing us to see the faint wispy outer 18 00:01:09,520 --> 00:01:13,520 atmosphere of the sun we call the corona. 19 00:01:13,540 --> 00:01:17,620 [slate] 20 00:01:17,640 --> 00:01:21,700 Well this is a special opportunity because at any given 21 00:01:21,720 --> 00:01:25,790 location an eclipse, a total eclipse, is only about 2 to 7 minute 22 00:01:25,810 --> 00:01:29,960 But this one is traveling across the entire United States 23 00:01:29,980 --> 00:01:34,030 and so instead of having an individual observation of 24 00:01:34,050 --> 00:01:38,060 about 2 minutes, we actually get an observation of an hour 25 00:01:38,080 --> 00:01:42,160 and 30 minutes by putting together telescopes all 26 00:01:42,180 --> 00:01:46,210 along the path as well as balloons and sensors all along the path 27 00:01:46,230 --> 00:01:50,410 giving us a unique opportunity to see the rich outer 28 00:01:50,430 --> 00:01:54,490 atmosphere of the sun where all the solar activity happens 29 00:01:54,510 --> 00:01:58,570 In addition we get to the changes in the environment 30 00:01:58,590 --> 00:02:02,730 locally as this shadow passes across the Earth creating its own 31 00:02:02,750 --> 00:02:06,900 microclimate and we get to see the response of animals and plants. 32 00:02:06,920 --> 00:02:11,010 So it's a really amazing opportunity to see not only solar science but 33 00:02:11,030 --> 00:02:15,120 also Earth science in a special unique way. 34 00:02:15,140 --> 00:02:19,160 [slate] 35 00:02:19,180 --> 00:02:23,290 You know we've been looking at the 36 00:02:23,310 --> 00:02:27,440 corona, this outer atmosphere we see during a total solar eclipse 37 00:02:27,460 --> 00:02:31,530 at a distance for hundreds of years. But now we're 38 00:02:31,550 --> 00:02:35,620 launching a spacecraft in 2018, the Parker Solar Probe, which 39 00:02:35,640 --> 00:02:39,770 is going to go to the corona and we're going to get to experience 40 00:02:39,790 --> 00:02:43,970 up close and personal. Literally touching the sun 41 00:02:43,990 --> 00:02:48,040 We will now have unique and critical understanding 42 00:02:48,060 --> 00:02:52,180 that we've never had before of this really vital area in the sun's atmosphere. 43 00:02:52,200 --> 00:02:56,200 [slate] 44 00:02:56,220 --> 00:03:00,400 Well the 45 00:03:00,420 --> 00:03:04,450 sun is extremely active. Not only does it's outer atmosphere stream 46 00:03:04,470 --> 00:03:08,530 away and fill the whole solar system. But it also sends out these 47 00:03:08,550 --> 00:03:12,630 huge explosions of light and material and magnetic field 48 00:03:12,650 --> 00:03:16,750 out into the solar system. It interacts with all of our planets. And 49 00:03:16,770 --> 00:03:20,940 this actually is important for how we define habitability 50 00:03:20,960 --> 00:03:25,020 and what determines whether a planet is like Earth 51 00:03:25,040 --> 00:03:29,160 or a planet is like Mars which actually had its atmosphere stripped away 52 00:03:29,180 --> 00:03:33,320 over billions of years. And this not only tells us about our own 53 00:03:33,340 --> 00:03:37,390 solar system, but also about extra solar systems. Planets 54 00:03:37,410 --> 00:03:41,460 outside of our own solar system and other ones potentially 55 00:03:41,480 --> 00:03:45,580 at some point even in other galaxies, this is. Understanding 56 00:03:45,600 --> 00:03:49,760 our sun and it's interaction with the solar system is telling 57 00:03:49,780 --> 00:03:53,780 us how this happens everywhere in the universe. 58 00:03:53,800 --> 00:03:57,800 [slate] 59 00:03:57,820 --> 00:04:01,990 Well what happens is 60 00:04:02,010 --> 00:04:06,050 the moon doesn't actually orbit in the same plane 61 00:04:06,070 --> 00:04:10,140 as the Earth is orbiting around the sun. In fact 62 00:04:10,160 --> 00:04:14,260 it is slightly inclined approximately 5 degrees 63 00:04:14,280 --> 00:04:18,460 And so what that means is sometimes the moon is 64 00:04:18,480 --> 00:04:22,530 a little bit above the Earth when it casts its shadow 65 00:04:22,550 --> 00:04:26,640 and sometimes it's a little bit below the Earth when it casts its shadow. But 66 00:04:26,660 --> 00:04:30,780 every so often it actually lines up just perfectly 67 00:04:30,800 --> 00:04:34,980 and the shadow is cast on the Earth giving us a partial 68 00:04:35,000 --> 00:04:39,000 and sometimes a total solar eclipse. 69 00:04:39,020 --> 00:04:43,020 [slate] 70 00:04:43,040 --> 00:04:47,040 [slate] 71 00:04:47,060 --> 00:04:51,110 One of the really spectacular things that we've gotten out of 72 00:04:51,130 --> 00:04:55,210 the Lunar Reconnaissance Orbiter, NASA's mission at the moon right now, is the highest resolution 73 00:04:55,230 --> 00:04:59,360 topographic map of any planetary body in the solar system. And that 74 00:04:59,380 --> 00:05:03,390 allows us to accurately predict the path of totality, the shadow 75 00:05:03,410 --> 00:05:07,460 upon the face of the Earth. We now know that path is not a perfect 76 00:05:07,480 --> 00:05:11,560 circle or an ellipse. It's actually an irregularly shaped object. 77 00:05:11,580 --> 00:05:15,730 We can predict exactly where that path will pass across 78 00:05:15,750 --> 00:05:19,910 the United States and allow folks the best opportunities to predict 79 00:05:19,930 --> 00:05:24,010 what and when they'll see the total eclipse. 80 00:05:24,030 --> 00:05:28,020 [slate] 81 00:05:28,040 --> 00:05:32,130 [Young] You can learn more about 82 00:05:32,150 --> 00:05:36,250 eclipses and safety and all the exciting stuff we're doing at 83 00:05:36,270 --> 00:05:40,290 eclipse2017.nasa.gov and check us out on Twitter 84 00:05:40,310 --> 00:05:44,858 @NASASun.