WEBVTT FILE 1 00:00:00.040 --> 00:00:04.030 [slate] Well this is a really exciting 2 00:00:04.050 --> 00:00:08.030 event for us because the transit of Mercury only happens rarely once every 3 00:00:08.050 --> 00:00:12.040 the last one was 10 years ago. And it happens when Mercury passes 4 00:00:12.060 --> 00:00:16.040 between us and the sun. It blocks out part of the light from the sun 5 00:00:16.060 --> 00:00:20.040 Now today this transit is starting at 7:12 a.m. 6 00:00:20.060 --> 00:00:24.140 East coast time and will end at 2:30 p.m. Again East coast time. 7 00:00:24.160 --> 00:00:28.190 And you can observe it from the ground if you have the right equipment particularly 8 00:00:28.210 --> 00:00:32.190 safety equipment. But really the best place to observe it by going to 9 00:00:32.210 --> 00:00:36.200 the NASA website and watching the live stream data coming from the Solar Dynamics Observatory 10 00:00:36.220 --> 00:00:40.210 [slate] 11 00:00:40.230 --> 00:00:44.250 Well astronomers have been using transit data to understand our solar system 12 00:00:44.270 --> 00:00:48.250 and beyond for literally hundreds of years. 13 00:00:48.270 --> 00:00:52.260 Originally those transits were used to establish a yard stick 14 00:00:52.280 --> 00:00:56.260 to measure the sizes of things in our own solar system. But since then 15 00:00:56.280 --> 00:01:00.270 we've also used transits to understand the atmospheres of the planets in our solar system. 16 00:01:00.290 --> 00:01:04.320 We've used the transit of Mercury in fact as the first 17 00:01:04.340 --> 00:01:08.320 test of general relativity. And now we're using transits 18 00:01:08.340 --> 00:01:12.330 to learn for planets around distant stars. To look for exoplanets. 19 00:01:12.350 --> 00:01:16.350 [slate] 20 00:01:16.370 --> 00:01:20.390 Well the sun is fascinating. It's obviously very important to us. And one of the things 21 00:01:20.410 --> 00:01:24.400 we've discovered over years and years of study is that every time you look at the sun 22 00:01:24.420 --> 00:01:28.400 in more detail, you find more structure. And in fact 23 00:01:28.420 --> 00:01:32.400 now the Solar Dynamics Observatory is looking at the sun with 24 00:01:32.420 --> 00:01:36.410 the best resolution ever. And we're learning more than ever before about 25 00:01:36.430 --> 00:01:40.420 the magnetic fields of the sun. About flares, about spots 26 00:01:40.440 --> 00:01:44.430 about the activity that's going on in our own sun. And 27 00:01:44.450 --> 00:01:48.440 by understanding that we start to understand how the sun can actually 28 00:01:48.460 --> 00:01:52.440 have an effect on us here on Earth. [slate] 29 00:01:52.460 --> 00:01:56.440 Well astronomers have been using the transit method 30 00:01:56.460 --> 00:02:01.720 to find exoplanets for a number of years now. And in fact we've found literally thousands 31 00:02:01.740 --> 00:02:05.720 of exoplanets so far. But the upcoming TESS mission -the 32 00:02:05.740 --> 00:02:09.730 Transiting Exoplanet Survey Satellite - is going to survey the entire sky looking for 33 00:02:09.750 --> 00:02:13.730 transiting planets around bright, nearby stars 34 00:02:13.750 --> 00:02:17.740 Now these exoplanets, this list of targets 35 00:02:17.760 --> 00:02:21.740 is going to be the perfect list of targets for follow up observations 36 00:02:21.760 --> 00:02:25.750 using telescopes such as the James Webb Space Telescope or other facilities 37 00:02:25.770 --> 00:02:29.760 to try to get the follow up data to help us understand these planets. 38 00:02:29.780 --> 00:02:33.760 And that means understanding what they're made out of. Understanding 39 00:02:33.780 --> 00:02:37.760 what they're atmospheres are like and maybe even finding signs of habitability. 40 00:02:37.780 --> 00:02:41.760 [slate] 41 00:02:41.780 --> 00:02:45.770 Well go to www.nasa.gov/transit 42 00:02:45.790 --> 00:02:49.770 And if you go to that website you will find an array of 43 00:02:49.790 --> 00:02:53.770 stunning images of the sun and of the transit. And importantly you'll find a link 44 00:02:53.790 --> 00:02:57.780 to the live stream data coming from the Solar Dynamics Observatory 45 00:02:57.800 --> 00:02:59.926 as it happens.