>> Hi, I'm Nicky Fox.
And I'm in charge of all
sun science here at NASA.
Oh.
This is "Ask NASA,"
and I'm here to answer
your questions.
"Is the sun a ball of fire?"
No, it's not.
We know that the sun
can't be a ball of fire,
because we need oxygen
to be able to have combustion
and there's no oxygen in space.
The sun, however,
is a giant nuclear furnace.
The core in the very center
is very, very similar
to a nuclear reactor.
And all of the--
these particles get
squashed together and there's
a huge amount of pressure.
And they go--
undergo chemical reactions.
And so there are very different
layers as you move out
towards the edge of the sun.
"Why does NASA send
missions to the sun?"
Because the sun
is the most important thing
in our solar system.
The sun generates light
but also a tremendous
amount of energy.
And it sends all of this
material to us here on Earth,
and so we live in the extended
atmosphere of the sun.
We've looked at the sun
in every different wavelength.
But recently, NASA launched
the Parker Solar Probe
which is a daring mission
to go into the very atmosphere,
the very heart
of the atmosphere of the sun.
So I have a model
of the Parker Solar Probe
spacecraft here.
Can I get some sun
in here, please?
So the important thing
is as the spacecraft
moves around the sun,
the heat shield has
to remain pointed towards
the sun at all times.
So the heat shield--
the front of the heat shield
will get to about
2,500 degrees Fahrenheit.
But the main body
of the spacecraft is nice
and cool at about
80 degrees Fahrenheit.
Which is a bit like a balmy,
Florida evening in August
I guess!
And that's Parker Solar Probe.
Thank you!
Good!
[ laughter ]
>> I love how polite you are!
[ laughter ]
>> So one of the things
that we discovered
with Parker Solar Probe
on the very first orbit
was switchbacks.
Switchbacks...
If only I had a model
of The Corona.
Oh, thank you!
So, switchbacks are really
reversals in the material
coming from the sun.
So the sun has a magnetic field
and that is continually
moving away--
or so we thought, continually
moving away from the sun.
But what we found
with Parker Solar Probe
is this magnetic field
actually kind of
reverses on itself
and makes an "S" shape.
We call that a switchback.
It's hard to twist
a magnetic field,
it's like trying to twist
a rubber hose-- it's hard!
And so, somehow there's
this energy going into th--
the magnetic field
that's causing this "S" shape.
And when it releases,
it's letting all of this excess
energy out into the solar wind.
Thank you.
Studying the sun is really
important as we get ready
to support the Artemis mission.
We're really protected here
on the planet by our
magnetic field and all
of that atmosphere around us.
Our astronauts, when they--
they will be on the moon.
And of course, as we journey
further to Mars and beyond,
we'll be traveling through
the solar wind and living
really more in the atmosphere
of the sun.
And so it's key as we
go forward to the moon,
to Mars and beyond
with our Artemis mission
that we really understand
the source of energy
in the heart
of our solar system.
Parker Solar Probe
on her final closest approach
after she's done all
of those Venus flybys,
she will be about 3.9 million
miles above the sun's surface.
We have many materials
on Parker Solar Probe
that don't melt despite
how close they are to the sun.
In fact, that was one
of the big technology
challenges for us
to find materials not only
that don't melt,
but can actually withstand
the incredible change
in temperature because
Parker goes very close
to the sun and then comes out
around the orbit of Venus.
Which means that all
these materials go really
hot and then really cold
at least 24 times.
So the critical thing
for Parker Solar Probe,
of course, is to keep
that heat shield pointing
at the sun.
At some point,
she will run out of fuel.
At that point, unfortunately,
she will start to turn.
And the full illumination
of the sun will hit parts
of the spacecraft that are not
designed to see the sun.
And so she'll break up
into large pieces,
and then they will get
gradually smaller and smaller
until they become really tiny.
And so I like to think
that she will become part
of the Corona, and she will
orbit the sun forever.
So honestly, we don't know
what new science
we're going to expect.
We've already seen
unbelievable stuff on
our first couple of orbits.
Science is a voyage
of discovery.
And that is what
Parker Solar Probe is doing,
she is going into a region
where we've never been before.
And so honestly?
We expect the unexpected.
My favorite aspect about
the sun is it's a star.
And it's a star that
we can go and visit.
And so you think, you know,
you look up in the night sky,
you see all of those stars
and yet we're actually
sending a spacecraft
right into the atmosphere
of a star right now.
And that means we're going
to understand more about
other stars in our universe.
And that's amazing.
>> Do you have a question
for NASA?
Send your questions
to our experts on Twitter
using #AskNASA.