#AskNASA┃ Is the Sun a ball of fire?

>> Hi, I'm Nicky Fox.

And I'm in charge of all

sun science here at NASA.


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!


[ 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.


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.

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