[slate]
So on August 21st of this year, the moon, sun and Earth
will line up just perfectly so that the moon
comes between the Earth and the sun and casts its shadow
down onto the United States. And
starting in Oregon, the core of its shadow
called the umbra is going to travel across the U.S. in about
1.500 miles per hour ending in South Carolina
and everyone in North America, Central America and
a good portion of South America are going to also experience a partial
solar eclipse. And if you happen to be in that 70 mile
wide path we just saw then you'll get to experience a total
solar eclipse where the moon completely blocks out the bright solar
disk allowing us to see the faint wispy outer
atmosphere of the sun we call the corona.
[slate]
Well this is a special opportunity because at any given
location an eclipse, a total eclipse, is only about 2 to 7 minute
But this one is traveling across the entire United States
and so instead of having an individual observation of
about 2 minutes, we actually get an observation of an hour
and 30 minutes by putting together telescopes all
along the path as well as balloons and sensors all along the path
giving us a unique opportunity to see the rich outer
atmosphere of the sun where all the solar activity happens
In addition we get to the changes in the environment
locally as this shadow passes across the Earth creating its own
microclimate and we get to see the response of animals and plants.
So it's a really amazing opportunity to see not only solar science but
also Earth science in a special unique way.
[slate]
You know we've been looking at the
corona, this outer atmosphere we see during a total solar eclipse
at a distance for hundreds of years. But now we're
launching a spacecraft in 2018, the Parker Solar Probe, which
is going to go to the corona and we're going to get to experience
up close and personal. Literally touching the sun
We will now have unique and critical understanding
that we've never had before of this really vital area in the sun's atmosphere.
[slate]
Well the
sun is extremely active. Not only does it's outer atmosphere stream
away and fill the whole solar system. But it also sends out these
huge explosions of light and material and magnetic field
out into the solar system. It interacts with all of our planets. And
this actually is important for how we define habitability
and what determines whether a planet is like Earth
or a planet is like Mars which actually had its atmosphere stripped away
over billions of years. And this not only tells us about our own
solar system, but also about extra solar systems. Planets
outside of our own solar system and other ones potentially
at some point even in other galaxies, this is. Understanding
our sun and it's interaction with the solar system is telling
us how this happens everywhere in the universe.
[slate]
Well what happens is
the moon doesn't actually orbit in the same plane
as the Earth is orbiting around the sun. In fact
it is slightly inclined approximately 5 degrees
And so what that means is sometimes the moon is
a little bit above the Earth when it casts its shadow
and sometimes it's a little bit below the Earth when it casts its shadow. But
every so often it actually lines up just perfectly
and the shadow is cast on the Earth giving us a partial
and sometimes a total solar eclipse.
[slate]
One of the really spectacular things that we've gotten out of
the Lunar Reconnaissance Orbiter, NASA's mission at the moon right now, is the highest resolution
topographic map of any planetary body in the solar system. And that
allows us to accurately predict the path of totality, the shadow
upon the face of the Earth. We now know that path is not a perfect
circle or an ellipse. It's actually an irregularly shaped object.
We can predict exactly where that path will pass across
the United States and allow folks the best opportunities to predict
what and when they'll see the total eclipse.
[slate]
[Young] You can learn more about
eclipses and safety and all the exciting stuff we're doing at
eclipse2017.nasa.gov and check us out on Twitter
@NASASun.