Well it may not feel like it in parts of the country, but spring begins today.
March 20th kicks off the first day of Astronomical Spring
in the Northern Hemisphere and on this day the Sun will pass directly
over the Earth's equator, giving the entire planet equal hours of
day and night. Here to tell us about the equinox
is Dr. Nicki Viall at NASA Goddard Space Flight Center, Thanks for
joining us. (Dr. Viall) Thanks for having me. (reporter) Now start by telling us
what is an equinox? (Dr. Viall) Equinox in Latin means
equal night, and that's what is exactly happening today, the day and the night
are of equal length. Now this only happens twice per year, on the Spring
equinox and on the Fall equinox. The rest of the time
the planet is unevenly illuminated, that means one hemisphere will receive
more light than the other hemisphere. This has to do with the rotation
the occasional axis of the Earth and how that is tilted relative to the orbital
plane that the Earth orbits the Sun around. So what that means is that
part of the year the Northern Hemisphere were we live will be pointed
towards the Sun and receive a longer day and more sunlight and in the
part of the year it will be tilted away from the Sun.
and receive less sunlight and longer nights
and then equinoxes is when we pass in between those two extremes.
(reporter) Now there's an exciting event this year. A total solar
eclipse. When is this happening and can we expect?
(Dr. Viall) Yeah, so the total solar eclipse that's happening August 21st, this is
a super cool event. It is when the moon
passes in between the Earth and the Sun. So that means that
the moon's shadow will be on the Earth and
when you are in the path of totality that the Earth
the moon totally blocks out the main body of the
Sun's light, so we can see the solar corona or the solar atmosphere
around the moon. (reporter) NASA will be doing some pretty cool
science during the eclipse. Talk about how NASA is
using the eclipse to study the Sun and the Earth.
(Dr. Viall) So this total solar eclipse is really neat, because it crosses from coast to
coast of the United States. This hasn't happen since 1918.
in the United States. So this is as I said, an opportunity to study
the solar corona or solar atmosphere. The public can get
involved too. We are doing a citizen science and you can find out
about that on eclipse2017.nasa.gov. But what we're going to be studying
is the solar corona, this magnetically, active
solar atmosphere, there is so much magnetic energy that's being
imparted into the solar corona all the time, makes the solar corona very hot
it also creates something that we call space weather, which are these big
exploding on the Sun, the magnetic explosions that can launch
magnetized plasma towards the Earth and cause things like the
Aurora Borealis. (reporter) How do eclipses help
us find planets orbiting other stars? (Dr. Viall) So an eclipse is
just a special type of transit. A transit is any time
a body comes between it's parent star and the Earth were we
observing that parent star. What happens is the
amount of light that we receive from that star goes down as the planet crosses
in front of the star. Bigger planets block out more light and small
planets block out less light. This is one of the ways we can find exo-planets
or planets in other solar systems orbiting other stars.
(reporter) Where can we learn more about the upcoming eclipse?
(Dr. Viall) eclipse2017.nasa.gov is the place
to go, here you can find out safety information for how to safely to watch the
eclipse. You can see a map of exactly where the path of totality
is whether you'll be getting partial eclipse or total solar eclipse
NASA is a good place to go to just learn
more about the great science we're doing here at NASA.
(reporter) Thanks so much. (Dr. Viall) Thank You.