WEBVTT FILE 1 00:00:00.040 --> 00:00:04.070 Well it may not feel like it in parts of the country, but spring begins today. 2 00:00:04.070 --> 00:00:08.130 March 20th kicks off the first day of Astronomical Spring 3 00:00:08.130 --> 00:00:12.200 in the Northern Hemisphere and on this day the Sun will pass directly 4 00:00:12.200 --> 00:00:16.330 over the Earth's equator, giving the entire planet equal hours of 5 00:00:16.330 --> 00:00:20.520 day and night. Here to tell us about the equinox 6 00:00:20.520 --> 00:00:24.710 is Dr. Nicki Viall at NASA Goddard Space Flight Center, Thanks for 7 00:00:24.710 --> 00:00:28.760 joining us. (Dr. Viall) Thanks for having me. (reporter) Now start by telling us 8 00:00:28.760 --> 00:00:32.850 what is an equinox? (Dr. Viall) Equinox in Latin means 9 00:00:32.850 --> 00:00:36.900 equal night, and that's what is exactly happening today, the day and the night 10 00:00:36.900 --> 00:00:40.960 are of equal length. Now this only happens twice per year, on the Spring 11 00:00:40.960 --> 00:00:44.990 equinox and on the Fall equinox. The rest of the time 12 00:00:44.990 --> 00:00:49.080 the planet is unevenly illuminated, that means one hemisphere will receive 13 00:00:49.080 --> 00:00:53.170 more light than the other hemisphere. This has to do with the rotation 14 00:00:53.170 --> 00:00:57.210 the occasional axis of the Earth and how that is tilted relative to the orbital 15 00:00:57.210 --> 00:01:01.240 plane that the Earth orbits the Sun around. So what that means is that 16 00:01:01.240 --> 00:01:05.310 part of the year the Northern Hemisphere were we live will be pointed 17 00:01:05.310 --> 00:01:09.410 towards the Sun and receive a longer day and more sunlight and in the 18 00:01:09.410 --> 00:01:13.590 part of the year it will be tilted away from the Sun. 19 00:01:13.590 --> 00:01:17.780 and receive less sunlight and longer nights 20 00:01:17.780 --> 00:01:21.820 and then equinoxes is when we pass in between those two extremes. 21 00:01:21.820 --> 00:01:25.880 (reporter) Now there's an exciting event this year. A total solar 22 00:01:25.880 --> 00:01:29.990 eclipse. When is this happening and can we expect? 23 00:01:29.990 --> 00:01:34.120 (Dr. Viall) Yeah, so the total solar eclipse that's happening August 21st, this is 24 00:01:34.120 --> 00:01:38.310 a super cool event. It is when the moon 25 00:01:38.310 --> 00:01:42.490 passes in between the Earth and the Sun. So that means that 26 00:01:42.490 --> 00:01:46.690 the moon's shadow will be on the Earth and 27 00:01:46.690 --> 00:01:50.720 when you are in the path of totality that the Earth 28 00:01:50.720 --> 00:01:54.790 the moon totally blocks out the main body of the 29 00:01:54.790 --> 00:01:59.060 Sun's light, so we can see the solar corona or the solar atmosphere 30 00:01:59.060 --> 00:02:03.240 around the moon. (reporter) NASA will be doing some pretty cool 31 00:02:03.240 --> 00:02:07.260 science during the eclipse. Talk about how NASA is 32 00:02:07.260 --> 00:02:11.290 using the eclipse to study the Sun and the Earth. 33 00:02:11.290 --> 00:02:15.360 (Dr. Viall) So this total solar eclipse is really neat, because it crosses from coast to 34 00:02:15.360 --> 00:02:19.450 coast of the United States. This hasn't happen since 1918. 35 00:02:19.450 --> 00:02:23.640 in the United States. So this is as I said, an opportunity to study 36 00:02:23.640 --> 00:02:28.010 the solar corona or solar atmosphere. The public can get 37 00:02:28.010 --> 00:02:32.070 involved too. We are doing a citizen science and you can find out 38 00:02:32.070 --> 00:02:36.200 about that on eclipse2017.nasa.gov. But what we're going to be studying 39 00:02:36.200 --> 00:02:40.720 is the solar corona, this magnetically, active 40 00:02:40.720 --> 00:02:44.750 solar atmosphere, there is so much magnetic energy that's being 41 00:02:44.750 --> 00:02:48.800 imparted into the solar corona all the time, makes the solar corona very hot 42 00:02:48.800 --> 00:02:52.870 it also creates something that we call space weather, which are these big 43 00:02:52.870 --> 00:02:56.990 exploding on the Sun, the magnetic explosions that can launch 44 00:02:56.990 --> 00:03:01.180 magnetized plasma towards the Earth and cause things like the 45 00:03:01.180 --> 00:03:05.360 Aurora Borealis. (reporter) How do eclipses help 46 00:03:05.360 --> 00:03:09.400 us find planets orbiting other stars? (Dr. Viall) So an eclipse is 47 00:03:09.400 --> 00:03:13.460 just a special type of transit. A transit is any time 48 00:03:13.460 --> 00:03:17.590 a body comes between it's parent star and the Earth were we 49 00:03:17.590 --> 00:03:21.730 observing that parent star. What happens is the 50 00:03:21.730 --> 00:03:25.910 amount of light that we receive from that star goes down as the planet crosses 51 00:03:25.910 --> 00:03:29.940 in front of the star. Bigger planets block out more light and small 52 00:03:29.940 --> 00:03:33.970 planets block out less light. This is one of the ways we can find exo-planets 53 00:03:33.970 --> 00:03:38.030 or planets in other solar systems orbiting other stars. 54 00:03:38.030 --> 00:03:42.080 (reporter) Where can we learn more about the upcoming eclipse? 55 00:03:42.080 --> 00:03:46.240 (Dr. Viall) eclipse2017.nasa.gov is the place 56 00:03:46.240 --> 00:03:50.420 to go, here you can find out safety information for how to safely to watch the 57 00:03:50.420 --> 00:03:54.610 eclipse. You can see a map of exactly where the path of totality 58 00:03:54.610 --> 00:03:58.660 is whether you'll be getting partial eclipse or total solar eclipse 59 00:03:58.660 --> 00:04:02.740 NASA is a good place to go to just learn 60 00:04:02.740 --> 00:04:06.860 more about the great science we're doing here at NASA. 61 00:04:06.860 --> 00:04:08.131 (reporter) Thanks so much. (Dr. Viall) Thank You.