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So during a solar

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eclipse,
the sun, moon and earth are lined up

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so that the sun shines on the moon,
which then casts a shadow on the earth.

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And so in the United States,
in the contiguous United States,

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everyone will have an opportunity
to see at least a partial solar eclipse.

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And so that's when the moon moves across

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and partially blocks out the sun's disk.

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There is also a narrow path
that moves from Texas

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up to New England,
where you can experience totality.

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So for a brief period of time
as that shadow is moving across,

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you will see the moon
completely BLOCK the sun out.

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And that then reveals the sun's outer
atmosphere called the corona.

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The rest of the time,
it's still a partial eclipse,

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but in that narrow time period, that's

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when you can experience the full aspect of
what is a total solar eclipse.

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Well,

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yeah, so there's a couple of ways
we can do that.

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So except for that narrow time,
when you're in totality,

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the rest of the time is what we call

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a partial eclipse,
where the sun is only partially blocked

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and it's always, always too bright
to look at just normally like the sun.

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So what you want to do is if you want to
look at it directly, you want to have safe

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solar viewing glasses or eclipse glasses,

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and then you're able to look up and safely
see it.

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Now, if you don't have solar
viewing glasses,

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then what you can do is
you can create a projector which projects

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the sun's image onto a piece of paper
or the ground, or you can even take

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a piece of paper with holes punched in it,
which makes a pinhole camera

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that allows you to see the sun
the crescents cast onto the ground.

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You can even take your hands,
do them like this with the sun behind you.

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And that creates a little pinholes.

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And it's actually much like

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what happens with the leaves in the trees,
which is just an amazing thing to see.

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Well,

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I am really,
really, really stoked to see the corona.

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I mean, the corona,
the outer part of the sun's atmosphere

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is what I've been studying for 20 years,
but I have always studied it from space.

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When you can't actually see
this part of the atmosphere

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and the only time you can see it is
when you're in totality on the ground.

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So I will see the part of the sun
I study with my own eyes.

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But you know more than that,
it's a really amazing experience.

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Once I first saw a total solar eclipse,
I was hooked.

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And I'm really excited because I will get
to experience this with my wife.

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And this is just such
an amazing opportunity

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to share
and with all of the people around you.

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Well, this is a really amazing
opportunity.

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Nature is giving us a laboratory
to study many aspects.

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One, of course, is the corona,
which is very, very important.

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It's much, much hotter
by 100 times than the surface of the sun.

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And it is where solar activity and space
weather

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comes from huge explosions
that send out solar material.

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And so this is a really important
opportunity to study that.

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But also as we study
that shadow moving across the country

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and we see the change
in light in the atmosphere,

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it allows us to study the lower
atmosphere, clouds and temperature,

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and it also allows us to study
the very important upper atmosphere

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called the ionosphere, which is critical
for our daily communications.

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And this is giving scientists
a really special opportunity

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to do an experiment that can only be done
during a total solar eclipse.

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Well, the sun has an activity cycle.

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It gets magnetically excited.

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The magnets, the magnetism builds up in it

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and it releases energy
as it gets more and more twisted.

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So we go from very low activity
or solar min [minimum] to high activity.

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Solar maximum back down to low.

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We are currently either in
or getting close to solar maximum.

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So this is the most activity,

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most space weather
we could possibly see will be happening.

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And this is a great time to study that
because it has such a huge impact

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on our society
and scientists will take this opportunity

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to learn more about our own star
and how it affects our daily

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lives.

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It's an amazing achievement for humanity.

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This is the fastest
are totally autonomous spacecraft

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it's ever been created,
and it's already, since 2018,

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been traveling, orbiting the sun,
getting closer and closer.

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It's already started flying
through the sun's corona, this part

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that we see during a total solar eclipse.

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And on December 24th,
it will make its closest approach.

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It will be less than 4 million miles
from the surface of the sun.

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Now, this doesn't seem like that's very,
very close.

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But remember, the sun is 93 million
miles away, so this is less than 4%

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a distance,
allowing us to study this really important

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part of the sun's atmosphere.

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Well, yeah.

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So there's been a huge explosion
in our ability

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to make better predictions,
which also includes making better maps.

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And one of the keys to
this is the data that we get

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from the Lunar Reconnaissance Orbiter.

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This is providing an incredibly detailed

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profile of the edge of the moon,

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which has a huge impact on how the shadow

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is cast on earth and the structure
of that shadow and the timing.

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We've also used data
about the Earth itself.

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So combining the
the the changes in the Earth

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as well as the structure of the moon,
has given us unprecedented abilities

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to predict the timing, as well as the maps

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that we use to know where
and when the eclipse will be.

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Yeah, so a transit is

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when a planet, for example, moves
in front of a star.

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Now, of course, for the eclipses
we're talking about,

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the moon is moving in front of the sun
and completely blocking it out.

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But distant stars have little planets
that are moving in front of them.

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And by looking at how the light changes
as the planet moves across it

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very subtly,
we can see the size of the planet.

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The bigger
the drop, the bigger the planet.

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But we can also look
at the different colors of light

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that are coming through the edge
of that planet, which is allowing us to

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to study the atmospheres of those planets.

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This is something that's happening
with James Webb Space Telescope,

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and we will be building
even better instruments in the future

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to help us figure out if life is possible
or maybe even if life

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exists on other planets
outside of our own solar system.

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Well, there are a lot of

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great tips,
participatory science opportunities.

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Now, NASA has created a several apps
that you can download for your phone.

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One is called Globe Observer,
which is a yearlong project,

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but they have a special Eclipse
app that during the eclipse

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you can participate and take measurements
of temperature and clouds.

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There's also one called Sun Sketcher,

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which is allowing you to sketch
and to take images of the corona.

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And Eclipse Soundscapes is allowing

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people to take sounds to record
sounds that are happening as the

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the wildlife changes during the eclipse
and bring back that data

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to allow NASA's scientists,
but also to have

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the public participate as a scientist
to help us gather more data

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so that we can better understand

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all of the amazing things
that we can learn during a solar eclipse.

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Well, it wasn't too long

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after Einstein had proposed his theory
of general relativity,

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which basically says that a massive object

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like the sun literally bends space.

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And a consequence of that is this light
travels through that bent space.

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The light itself bends.

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And so the gravity of the sun
acts like a lens

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and bends starlight
when it travels around it.

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So during a total solar eclipse,
when the bright disk

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is blocked out,
we can see background stars.

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But the positions of those stars
are slightly shifted

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because of the bending of the light
going around the sun.

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So we know exactly where they are.

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We see them in a different location
and that allows us to

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confirm the results
of what general relativity

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predicts will happen when that star
star's light passes the Sun.

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Well, the viewers can go to

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go that NASA dot gov slash eclipse 2024 [go.nasa.gov/eclipse2024].

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And there you can find out
about the citizen science.

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You can participate in
see live feeds across the country

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and find out about all of the
opportunities so that you can participate,

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whether you're in the path
or out of the path.

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There are lots of things
that people can enjoy

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and take that experience
and have it be something unique,

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something that they can experience and
share with all of the people around them.