>> Stephanie Marcus:
Good morning and welcome
to our lecture today from NASA.
We are really glad
that you came.
And we got sunshine
here on a cloudy day.
So, [laughter].
Well, we got rain later.
So, this is a good day
to hear about the sun,
which will return I'm sure.
I'm Stephanie Marcus from
the Science Technology
and Business Division.
And this is our 13th year.
We have a list of lectures
for next year, another eight.
And so, we're ready
to go to town.
I would like to introduce,
now that I know how
to pronounce her
name, Nicholeen Viall.
She explained how it was French.
And then, it was anglicized.
So, she's not Vi-all [phonetic],
as I had been practicing
for the last several weeks.
She began her studies
in astronomy and physics
out in Seattle, Washington,
University of Washington.
And then, she did her
graduate work, both her masters
and her PhD at Boston
University.
And she was a NASA fellow.
And then, a permanent
NASA person.
But she must be very
valuable because she got one
of the early career wards
from NASA last year.
What is that called?
The Early Career
Achievement Medal.
Congratulations.
And a great honor
that surprised her,
which was the Karen Harvey Prize
from the American Astronomical
Society Solar Physics Division.
So, she knows her stuff.
Right now, she's
Deputy Project Scientist
for the STEREO Mission, which
is one of the solar missions.
And she'll update
us on that mission.
And all the other
solar missions.
We've heard about the
Parker Solar Probe.
And the Solar Dynamics
Observatory has been
out there a long time.
Wind Spacecraft actually
launched in 1994.
And the upcoming one, which
you might have seen the little
handout, is PUNCH, which
really is a great acronym.
So, please help me welcome
Nicholeen Viall to the Library.
Thank you.
>> Nicholeen Viall: Alright.
Thank you everybody.
So, I'm here to talk about the
sun, the sun and the solar wind
and the solar corona and
the space environment.
And you might not know what
any of those words mean.
Hopefully, the sun you knew.
But the rest of the words,
we're going to talk about
and I'm going to explain
what all of those words mean.
So, this is sort of
just a teaser image
that I have right here.
This is the total solar
eclipse from 2008,
an image form the
total solar eclipse.
And so, this is, gives
you sort of a sense
of how the sun is creating
it's space environment,
the space environment
that we live in.
That's sort of what
we're seeing here.
And I'll get more into
that in a little bit.
Alright. But I'm going to
start with this video here.
This is sort of a more typical
view of the sun, sunset.
How do we think of the
sun on a normal day?
Sunset is sort of a way that
we normally think of the sun.
On the left, this is
actually sunset on Mars.
But even there, it kind
of looks typical, right?
It's kind of just sunset.
This is sunset on the Earth.
It's blue at Mars.
This one was taken with
the Mars Curiosity Rover.
Maybe I'll play it again here.
Yeah. This is taken with
the Mars Curiosity Rover.
It is blue because of the
dust in Mars' atmosphere.
And so, that filters
out the red light.
And it's the blue
light that comes
through for sunset on Mars.
Whereas, on Earth,
it's the opposite.
It's the red light
that comes through
and the blue light
that's scattered.
So, that is the difference.
But still, it kind of looks the
same on Mars, kind of similar.
The sun looks kind of similar.
That's sort of how we're
used to seeing the sun.
A total solar eclipse
is something
that happens every
once in a while.
And this is a different kind
of way to look at the sun.
This is an atypical
view of the sun.
Now, first of all, you
should never look directly
at the sun unprotected.
There are special
glasses that you can get
to protect your eyes
from the sun.
You should never
look directly at it.
But during totality, during
a total solar eclipse,
which is when the moon
comes between the earth
and the sun blocking out
the bright disk of the sun.
Then, it is safe to
look at what remains.
And what remains is
the solar corona,
the atmosphere of the sun.
That's what we're seeing here.
This is just in white light,
just like what you
see with your eye.
So, the solar corona is
much, much less bright
than the solar photosphere.
That's what we call this
visible surface of the sun.
That's what you can see here.
How many people saw the
total solar eclipse in 2017?
>> Stephanie Marcus:
A partial total.
>> Nicholeen Viall: So, here
in D.C., it was partial.
There was totality went across
the, it started in Oregon
and came across the
United States and went
out through South Carolina.
It's pretty amazing.
It lasted a little over two
hours, an hour and a half maybe.
I think it was about
an hour and a half
that it crossed the
United States.
It was pretty amazing.
I was on location in Salem,
Oregon doing NASA coverage
of the, of Totality.
It was an amazing experience.
So, I highly recommend
seeing Totality if you can.
The partial solar eclipse
is pretty cool too.
That's where the sun partially
comes in front of the sun.
The moon partially comes
in front of the sun.
To see partial, the
partial phases, though,
you do have to wear
the safety glasses.
Alright. So, here's some other
images, also of the eclipse.
What you can see right here
is what's sometimes called the
diamond ring, which is just
after the sun has
gone behind the moon.
And it just starts
to peak back out.
There's a flash of light.
So, that's what they're
capturing over here.
And then, over here on
the right, I don't know
if that's showing up so
well with the reflection.
But there's.
You can see some red around the,
in the solar corona
here, in the atmosphere.
The red is from cooler material.
The chromosphere.
It's one of the layers
of the sun.
Chromo meaning color.
So, we call that
the chromosphere.
I'll show you that
a little bit later.
But you can get a hint of it
during a total solar eclipse.
Alright. This is actually from
the total solar eclipse on 2000,
the 2017 total solar eclipse.
This is just sort of
a processed image.
So, with your naked eye, our
eye doesn't quite have the
resolution or the dynamic range
to see all of the, you know,
this high level of detail.
But with some image processing,
you can pull those details out.
So, the first thing I want you
to notice is how enormously
complex the solar corona is.
There's a ton of structure here.
There's little structures
that seem to all be aligned.
There's structures
that are curved.
It's enormously complex.
So, this is the sun's
atmosphere.
What you're seeing
actually is density.
It's the electron
plasma around the sun.
That's what you're
actually looking at.
You're just viewing the
plasma around the sun.
So, when we look at
this view of the sun,
two questions come to mind.
Two questions that
NASA is investigating.
First of all, where did all
of this complexity come from?
What's making this complexity?
What is going on, on the
surface of the sun and below
to make all of this complexity?
That's the first question.
The second question is what
happens as this plasma expands
out into space, as all of these
electrons expand out into space?
What happens to that as
that fills the solar system?
So, both of these
questions are things
that NASA has launched
spacecraft to investigate.
Alright. So, there's one thing.
Well, there's a number
of things.
But the first thing I
want you to remember is
that different wavelengths,
so different kinds of light,
on the solar atmosphere.
When we look at the
solar atmosphere
in different wavelengths
of light, we're looking
at different temperatures.
That means that the
plasma or the plasma is
when the electrons are no
longer bound to their protons.
Different wavelengths correspond
to different temperatures.
So, when we look in different
ultraviolet or x-ray light,
you're actually seeing
different temperatures.
And because of the
temperature structure
of the solar atmosphere,
different temperatures
means different heights.
Alright. So, keep
that in your head
that different filters are
different temperatures.
And different temperatures
are different heights.
So, we can sort of probe the
layers of the atmosphere.
Woops. I didn't play the video.
Alright. Here we go.
Okay. So, this is The
Old Man in the Sun.
Like the Man in the Moon,
can you spot the face?
It's just, it's not
always there.
But the sun happened to
configure it's complexity
to kind of look like
a face in the sun.
So, that's visible
light right there.
This is another channel,
1600 angstroms.
This is hotter now.
Now, we're getting
up to 50,000 kelvin.
Now, we're at 600,000 kelvin.
Now, we're at a million kelvin.
Now, we're at two
million kelvin.
Now, we're at two
and a half million.
So, it just keeps
getting hotter and hotter.
Six million kelvin.
Ten million kelvin.
And there's the man.
And then, this is a
special filter that looks
at the magnetic field.
[Multiple speakers].
[Laughter].
Kind of looks like a monkey.
So, what's cool is you kind of
get a sense of how when you look
at the different wavelengths,
there's different structures.
So, that, that complexity
that we saw
in the total solar eclipse,
it comes through in
different ways depending
on the temperature.
And therefore, the height
that you're looking at.
So, I'll say a little
bit more about that.
The sun is very bright.
And it's highly complex in
ultraviolet and x-ray light.
Now, this is one of the
reasons that NASA has
to supply spacecraft
to look at all of this.
It's because the
ultraviolet light
and the x-ray light doesn't
come through to the ground.
So, we have to be out
in space to see it.
So, here what you're seeing
is Solar Dynamics Observatory.
Different, all of those
different wavelengths
that you saw, but were seeing
them in different slices.
So, you can kind of
see the complexity.
And then, watch as the
different filters rotate
across complexity.
And it looks different
in each of those filters.
So, remember, each of
these colors is a different
temperature, which
is a different height
in the atmosphere.
So, the fact that
the atmosphere,
the solar corona emits in this
x-ray and ultraviolet light is
because it's incredibly hot.
In fact, it's hundreds
of times hotter
than the solar photosphere,
what the visible surface below.
In fact, some areas
it's 500 times hotter.
So, I think you saw there
was a million or more kelvin
in the corona versus a
6,000-kelvin photosphere.
So, that's really crazy that
it's hundreds of times hotter
in the solar atmosphere.
That would be like if you
were standing at a fireplace
and as you walked away
from the fireplace,
it all of a sudden got
hundreds of times hotter.
That's not the way that
physics usually happens.
But we know that it's
ultimately that magnetic field.
And I'll show you some more
information about that.
It's the magnetic
field releasing energy
up in the corona.
That's what's making it so hot.
But we're still investigating
exactly how
that energy takes place, how
that energy release takes place.
Alright. So, back to the sort
of standard view of the sun,
back in the optical
light, visible light,
like you would see if you
were looking at the sun
with these special glasses.
This is taken with Solar
Dynamic Observatory.
Solar Dynamics Observatory
kind of looks
at the sun in high definition.
It's like high time resolution,
high special resolution,
higher than we had ever
taken of the sun before.
But, but all the time.
It's continuous coverage.
So, we have a lot of
information about the sun now.
So, the first thing you should
notice is these dark spots.
Those dark spots are sunspots.
They're actually, we
know now the regions
of concentrated magnetic
fields, so concentrated
that the light is
actually suppressed there.
So, these sunspots long
before we knew what they were,
people had been measuring them.
In fact, there's evidence
from thousands of years ago
of people measuring sunspots
on the sun and watching them.
Alright. Here's a
video where we, again,
go through the layers
of the sun.
We started on the photosphere.
And then, here's one of those
ultraviolet megakelvin type
plasma, a million
degrees, million kelvin.
This is another layer
added on top of that
where you can see the
next hottest layer,
like two and a half, three.
Then, here's a model
of the magnetic field
where they're rooted
in those sunspots.
And then, it comes
out into the corona.
So, we know that the magnetic
field is what's causing a lot
of that complexity.
How the magnetic
field is behaving.
How it, how it's dynamic.
That's what's creating
a lot of the complexity
and it's what's creating the
heat in the solar corona.
So, one thing to, to
remember is that the corona,
the solar atmosphere is so
hot and so highly ionized
that the electrons are
stripped away from their atoms,
from the protons primarily.
So, they're charged particles.
It's plasma.
And the key takeaway is that,
to remember throughout the rest
of this talk, is that
charged particles
or plasma can't cross
magnetic field lines.
It has to flow along
the magnetic fields.
So, that's, you can kind of see
that the plasma is following
those magnetic field lines.
Alright. So, NASA looks in
the ultraviolet and x-ray.
That's what this image
is down here of the sun.
This image in the middle
is the total solar eclipse
from the ground.
And then, this outside
field of view,
even though it's
false colored red,
it's actually taken
in white light.
This is from an artificial
eclipse.
So, the other thing that
NASA does is it takes,
creates artificial eclipses,
artificial total eclipses,
so that we can see
this solar corona
in white light, but
all the time.
So, this one was actually
taken with the SOHO mission.
But at the same time,
on the 21st in 2017,
so that we could line up
the stuff going down lower
in the atmosphere with the
stuff going on higher up.
And you can see that this
magnetic field that's creating
all of this structure,
it's creating structure
that persists all the way out
really far away from the sun.
And, in fact, the
solar corona is so hot,
and it has so much energy
that it continuously
streams away from the sun.
And it flows outwards to
become the solar wind.
It's supersonic.
It's goes incredibly fast,
400, 500 kilometers per second.
So, what you're seeing
here is the solar wind.
That's Mercury in
our field of view.
These are a series of
images taken with STEREO,
the Solar Terrestrial
Relationship,
Relations Observatory.
This is again, white light that
you could see with your eye.
So, if you had a
sensitive enough eye.
And if we didn't have scattering
through our atmosphere
and things like that.
So, this is one of these
artificial solar eclipses
that we create from space,
where there's the sun.
This is further out.
And then, here's
all the way out.
And you can see this plasma just
continuously expands outwards
and fills the solar system,
fills the whole system.
This is kind of a cartoon
representation of what we do
at NASA, what NASA Heliophysics.
That's the big word,
Heliophysics,
that we use to describe this
sort of study of the sun.
And how it impacts
the solar system.
And how it affects earth,
sun/earth interactions.
You may have heard the
word space weather,
the term space weather.
That's also means, you know,
how, what is the sun doing?
And how does that affect
our space environment?
So, this is just
meant to be a cartoon,
you know, it's not to scale.
It's a cartoon representation.
Some of this, though, is
from real imagery of the sun.
But there's the core,
where fusion is going on,
making all this energy.
The convection zone right
below the surface of the sun.
There's a lot of roiling and
boiling going on that stirs
up those magnetic fields.
That's where a lot of
the energy comes from.
That tangles the
magnetic fields.
Well, the energy
comes from the fusion.
But then, it gets tangled
up in the convection,
tangles up those magnetic fields
because those magnetic fields
come through the surface
of the sun, through
these sunspots.
And go out into the corona.
And that's where they
release their energy.
Let's see, here's solar wind,
a representation
of the solar wind.
Now, this is really important.
Here we are at Earth.
Notice that earth
has a magnetic field.
Now, remember charged particles
can't cross the magnetic
field lines.
That's really good.
Because it means that earth's
magnetic field protects us
from all of this plasma
that's coming off of the sun
and filling the solar
system and coming at us.
So, here, you're
seeing a representation
of earth's magnetic field.
And how it's standing off this
flow of plasma from the sun.
And we. This bubble that the,
that is created is
called the magnetosphere.
So, a big space weather event
that you might have heard
of is something called a coronal
mass ejection or a solar flare.
Those are related phenomena.
But they both have to do
with big magnetic
explosions on the sun.
And how those interact
then later with the earth.
So, I'm going to show you
a representation of that.
So, magnetic field lines
here, they're poking
up through the sunspots
on the surface of the sun.
Remember, they're
loaded with plasma
because the plasma can't cross
the magnetic field lines.
And as these field lines
get stressed and contorted,
because of all the
motions at the base
of those magnetic field lines,
it can lead to a giant explosion
called a coronal mass ejection.
And the light associated
with the explosion is
what we call the flare.
So, here it goes.
There's the coronal
mass ejection being shot
out into space.
It's loaded with plasma
in its magnetic field.
Here's an actual video of Solar
Dynamics Observatory actually
imaging this type of,
of event taking place.
Back to the cartoon.
And here, we see this blob, this
giant coronal mass ejection.
This blob of plasma being
shot out into space.
And it'll hit whatever planets
happen to be in the way.
The first one, of
course, is Mercury.
If Mercury is in it's path.
It depends, of course, which way
this coronal mass ejection goes
and where the planets are
that, at that particular time.
The next one it might
hit is Venus.
And how it interacts with each
planet has to do with whether
or not that planet
has a magnetic field
to stand off that plasma.
And also, the characteristics of
the planetary atmosphere and how
that responds to the
plasma and magnetic field.
Now, of course, at
earth we have both.
We have atmosphere that helps
protect us from radiation.
We also have magnetic field.
So, here, when it
gets to the earth.
Here we are at earth.
But it's okay.
We've got a magnetic field.
[Laughter].
There we are.
So. [Inaudible].
So, there our magnetic field
is standing off the plasma
and the magnetic field.
Now, it does interact with
our magnetic field, though.
And, in fact, the new stress
that this interactions
introduces
into our magnetic
field causes explosions
in our magnetic field.
Those explosions
accelerate particles and lead
to the aurora borealis
or the northern lights.
And the two experiences
that I've had
that are really amazing are
seeing the northern lights
in person.
The videos, even
though they're amazing,
just don't do it justice.
And seeing the total
solar eclipse.
Those are both events
that I highly recommend.
They're just, just amazing.
So, here's the aurora.
Now, this is the space
weather that occurs
on a big explosion day
that happens on the sun.
But, in fact, the
sun is always busy.
There's no such thing as
a quiet day on the sun,
even when it doesn't have
these big explosions.
[Music]. So, here's.
Back to the Solar Dynamics
Observatory imagery.
This is 171 angstrom.
So, we're looking a little
less than a megakelvin plasma.
So, we're looking in that
top layer of the sun.
The sun doesn't really
jerk around like that.
That's just how the
videos coming through.
[Laughter].
But the, the sun is rotating.
It takes about a month
for the sun to rotate.
Make a, make a circle.
And you can see all of these,
all of the dynamics going on.
All of the structure.
All of the rearrangement.
And remember that all has to
do with the magnetic field.
So, there's smaller explosions.
And smaller dynamics that
happen every single day.
There's no such thing as
a quiet day on the sun.
There's always dynamics
going on.
And we see these dynamics
on smaller scales.
And we see them on
larger scales.
So, understanding just how even
these smaller scale explosions
get out into the solar wind and
create dynamics and interact
with the planetary atmospheres
and magnetic fields is something
that I'm particularly studying.
Alright. Here's another
view of a different kind
of dynamics that's
occurring even on a quiet day.
This, we're looking at a
different, we're looking
at a cooler temperature.
This that red that I pointed
out during the solar eclipse.
So, this is hotter
plasma in yellow.
And then, cooler plasma in red.
So, there's dynamics.
We're zoomed in here.
So, we're zoomed into
the limb of the sun.
And there are all
these dynamics,
smaller scale dynamics.
But we believe this
particular dynamic is one way
that these little explosions are
helping this plasma to escape.
And it escapes on one end.
And then, on the other end,
some of it falls back to the sun
at these cooler temperatures.
And it's called coronal rain,
which is kind of interesting.
So, we believe it shoots
out some of the material.
And then, some of the material
cools back down and falls down.
And so, we can see actually
better the coronal rain
because of how dense it is.
And so, it emits.
It emits more.
It's brighter.
Alright. Now, we're
stepping out.
Here's. This is not
during the solar eclipse,
but I just put this
on here for scale.
That's kind of the
scale of the actual sun.
And then, this is one of these
artificial eclipse movies
that we see of all
of the plasma and all
of the variable coming
off from the sun.
Again, during a time
when there wasn't one
of these big explosions.
The solar wind, the sort of
quiescing state of the sun
as it shoots out all of this
plasma is filled with structure,
filled with little explosion
remnants and filled with waves.
So, this is imagery taken
with the STEREO spacecraft.
And this is not, actually,
the standard dataset
that STEREO produces.
We had to do a special campaign
run to see if we could pull
out this level of
detail in the imagery.
So, now I'm going to zoom in
on the same set of images.
But I'm going to zoom in on
just a little piece of it.
And show this movie.
And here, I've got a dot here.
It's hard to even see the dot.
That's the earth to scale.
So, you could see we're kind of.
The size of the whole earth is
almost one resolution element
on these images because we're
so far away from the sun.
So, we're just resolving.
These things that are just
barely resolvable are still the
size of the earth in
the magnetosphere.
So, all of this structure
when it gets
to the planetary atmosphere is,
in the planetary magnetosphere
is it still interacts.
And it's, the solar wind
is just very treacherous.
This is a simulation
of what it can do
when it gets to the earth.
Here, I'm showing
blue dots indicating
where we have spacecraft.
This is an actual event where
we've actually recorded in situ.
So, the difference between
remote data and in situ data.
Remote data are when you take
pictures from a distance of the,
of the sun, for example.
And you can take those images
in different wavelengths
and learn different information.
In situ is like when
you, it means right here.
And so, it's when you
stick a thermometer
or stick a measurement of
the density right here.
Where it is right here.
So, here what we're
looking at is in situ data
of the magnetosphere
and of the solar winds.
So, we're looking at the solar
wind right before it hits
the magnetosphere.
I'm going to start
that video again.
We're looking at
the solar wind right
as it hits the magnetosphere.
The spacecraft right
inside of the magnetosphere.
And the third, third
spacecraft that looks
at Van Allen radiation belts.
And I'll explain what
that is in a minute.
So, that's what these
traces show over here.
Solar wind that has
these structures in it.
And you can see this represents
the density, the colors.
I should've looped this video.
Oh well. The colors
represent the density.
And so, you can see it's
the red and the yellow.
It's flipping back and forth.
And that's because this is
meant to represent a series
of those structures coming
past the magnetosphere.
So, it rises and
falls, rises and falls.
And it's compressing
the magnetosphere.
It's kind of like
a forced breathing.
They squeeze the magnetosphere.
And then, they relax.
And then, the next one
comes by, and squeezed it.
And then, it goes.
And then, the next one comes
by and squeezes it again.
And a lot of these actually
come out periodically.
So, they'll be a train
of them that repeat
and repeat and repeat.
And that is what makes this
signature in the magnetosphere.
So, we see it in the solar wind.
They'll be a front of
structures that come through.
And then, we see when it
hits the magnetosphere.
This was the WIND
spacecraft saw that.
WIND has been up there
for 25 years now making
measurements upstream
of the magnetosphere.
Then, in the magnetosphere we
see that the, the structures
as they hit the magnetosphere,
they caused these structures,
the magnetosphere, to respond
with those, the forced
breathing.
Then, the radiation belts.
That's what I'm showing
down here respond
with the same structures.
So, here's an image that shows
the Van Allen radiation belts
are these energetic
particles that live
in the inner part of
our magnetosphere.
James Van Allen discovered them.
That's why they're called the
Van Allen radiation belts.
But remember, charged
particles can't cross magnetic
field lines.
So, they're kind of
just stuck there.
Sometimes they precipitate
down into earth's atmosphere.
And sometimes they get energized
from some of the dynamics
that happen outer in
the magnetosphere.
So, this is very
important to understand
because any spacecraft
flying through here is going
to impacted by these
highly energetic particles.
Alright. So, I think that
was a lot of motivation
on why we need to
understand this.
And why we need to understand
the sun, certainly on a big day.
But also, on a day when it's
quiet and not much is going on.
Because even on the quiet days,
there's a lot going on still.
So, those aren't, these
dynamics aren't as big
as the coronal mass ejections.
But this is what's
happening all the time.
This is like the steady beat
that's always happening.
So, what are we doing about it?
First of all, we have a new
mission that's coming up, PUNCH,
Polarimeter to Unify the
Corona and Heliosphere.
There were some stickers
out there.
Hopefully, you saw them.
So, this is a mission that was
just selected by NASA to fly.
It's going to fly in about
three years, hopefully.
It's what we call
a smaller mission,
a SMACS, a small explorer.
So, there are different
sizes of missions at NASA,
so that we can investigate
different types of problems.
So, PUNCH is one of
the smaller ones.
It's led out of Southwest
Research Institution
by Craig DeForest.
So, the first thing,
polarimeter.
What is that?
So, let's talk about that.
Light can be polarized.
And this is a visualization
showing how light can
be polarized.
Light is electromagnetic waves.
And these arrows here
represent these vectors,
represent the E-field
oscillations
and the B-field oscillations.
The electric field oscillations
and the magnetic field
oscillations associated
with those waves.
And depending on
how they line up,
they can be circularly
polarized,
or they can be linearly
polarized.
And how they are polarized tells
you about how they were made.
And also, about the kind
of plasma or the medium
that it came through
before you detected it.
So, PUNCH is flying a polarizer
to distinguish the different
kinds of polarizations.
Because you can use
that to understand
that actually the
kind of structure
that you're looking at.
So, PUNCH flies four smallsats,
which means smaller satellites.
And LEO, which is
low earth orbit.
So, these are satellites
that orbit the earth
and look at the sun.
Four satellites.
And together, we make a
mosaic of polarized images.
And again, it's white light.
So, like those artificial
eclipses that NASA likes to fly.
But the polarization gives
us actually information
about the 3D structure
of the, of the solar wind
or the structures within it.
So, right now, what we have,
our current capabilities.
Some of those images
that I showed before fill
this region of space.
The black regions
are blind spots.
So, we have a little
coronagraph.
Those were some of the, that's,
this square right here comes
from a little piece within that
little coronagraph right there.
Then, we have some imagers
that I showed earlier.
They get a little bit of space.
But they're very low resolution.
Both in time and in space.
Very low resolution.
So, you can see the big
coronal mass ejections.
But you can't see
the substructure
within the coronal
mass ejections.
And you can't see this kind
of structure that I'm showing
in the movie over here.
So, the idea with PUNCH, is
with those four spacecraft
and combining the imagery in all
four of them, we can fill in all
of these blind spots and
do it at this high temporal
and spatial resolution
all the time.
So, back to our cartoon
representation.
By doing that, we can understand
not just the coronal mass
ejection, but the substructure
within the coronal
mass ejection.
The shock formation in front
of the coronal mass ejection
and any structures up there.
How those big structures
are interacting with some
of the smaller structures
that we see already are there.
Whether they're compressing
them and amplifying them.
We can see all of the
structure that's there already.
How they interact
with each other.
How they create new structures.
How they combine and
maybe get amplified.
It takes about four days
for the solar wind to get
from the sun to the earth.
So, in that time, a lot
of stuff can happen.
And if a very fast coronal
mass ejection gets launched
into that medium, the coronal
mass ejection can come much
faster and plow into that
slower going solar wind.
And, you know, like a snowplow,
sort of fold it all up in front
of it and amplify
whatever's already there.
So, PUNCH will finally have the
resolution to really image that.
And the idea is to unify
this, all of this complexity
and structure in the solar
corona, the solar atmosphere
with the heliosphere,
with what's going
on in the solar system.
Alright. The other
way, and the other way.
There are lots of ways.
But one other way that NASA
is tackling this problem is
with Parker Solar Probe.
Parker Solar Probe
launched last year.
And, as I'm, the tagline is
a mission to touch the sun.
So, this is what I was
talking about the difference
between remote sensing
and in situ sensing,
like actually touching
the plasma,
literally touching the plasma
with your plasma analyzer.
Literally touching the
magnetic fields with your,
with your magnetic
field measurements.
So, that's what Parker
Solar Probe does is it,
it has gotten closer to the sun
than any spacecraft
has ever gotten before.
And made those in situ
measurements very close
to the sun.
It also has an imager.
But the imager is more
like a microscope,
as opposed to a remote
telescope.
This is who that's named after.
This is Parker.
This is Eugene Parker.
This mission is actually the
first time a mission has been
named after somebody while
they were still alive.
This is the first
time that happened.
All of the other missions
that have been named
after people happened
after they passed away.
So, this is Eugene Parker.
The reason it's named after
him is because in 1958,
he wrote a paper theorizing that
the solar corona ought to expand
out into the solar system.
And it ought to reach
supersonic speeds.
And this was before
we had measurements.
There was some evidence,
but not any sort
of direct measurements of it.
But he wrote a theoretical paper
that said it would be true.
And he was right.
Here's him at the launch last
year watching Parker Solar Probe
mission launch.
[ Inaudible ]
This is the launch.
>> Ten, nine, eight,
seven, six, five, four,
three, two, one, zero.
Liftoff of the mighty
four heavy rocket
with NASA's Parker Solar Probe.
A daring mission to shed
light on the mysteries
of our closest star, the Sun.
[ Inaudible ]
>> Twenty-five seconds
in the flight,
zero pressure [inaudible]
good on all three boosters.
>> Now, 35 seconds
in, zero pressure
on the [inaudible] booster.
It's throttling down to
the partial thrust mode.
This launch looks good.
[ Inaudible ]
>> Now, one minute into flight.
Equal trajectory
looking good right
down the middle [inaudible].
>> One minute 10
seconds into flight.
>> Nicholeen Viall: So, we
had a successful launch.
And what the Parker Solar
Probe does to get close
to the sun is it uses Venus
gravity assist to redirect it,
so that we can get
in close to the sun.
And that's what this
is showing here.
Green is the Parker Solar Probe.
And then, you can see, you can
see it's spiraling in closer
and closer and closer
to the sun.
So, I'm going to play
that video one more time.
So, it comes off.
And then, it does a Venus flyby.
And that's how it uses
the Venus gravity assist
to steer it in closer
to the sun.
And each Venus gravity assist
gets it a little bit closer.
So, we had one right
after launch.
And that got us in really close.
And then, it has
another one in December.
And that'll get it even closer.
We've had three passes
around the sun so far.
This here is just
showing its orbit.
And each of these green dots
is a Venus gravity assist.
So, it gets in close.
And then, it gets in close.
And then, it gets in close.
And then, it gets in close.
And then, we go to Venus.
And then, it gets even closer,
even closer, even closer.
That's what that is showing.
So, at its closest approach,
which will happen 2024 and 2025,
it's going to be
at 10 solar radii.
So, if you put a ruler on the
sun and had one unit be equal
to the radius of the sun,
then this is 10 times
that distance from the sun.
It's about four million miles.
So, just to give
you perspective.
Mercury was as close as
we had ever gone before.
The Helios missions a
long time ago, in the 70's
and 80's, had gone that close.
And measured the solar wind.
And they, that was all
the data that we had.
That was as close as we
had gone was Mercury.
Mercury is 35 million
miles from the sun.
So, this is, we're going to
get into four million miles.
So, almost a factor of 10 closer
than we had ever been before.
And already we're
closer to, than Mercury.
And already we're
getting new data.
There's way too many
words to read here.
So, don't read them.
But the point was just
this is listing all of,
sort of all of the documents,
official documents
recording the times
that solar probe was attempted
or the concept was attempted.
In fact, the idea that we
should probably send an in-situ
spacecraft to the sun and
have a probe predates NASA.
People have been
trying to do this.
We knew this was the
right thing to do.
The problem is you have
to not melt [laughter]
when you're close to the sun.
So, in fact, it required a
lot of technological advances
to be able to do this
in a cost-effective way.
The heatshield being
a major piece of that.
So, the heatshield that
keeps the heat away
from all the instruments.
Alright. So, Parker Solar
Probe is investigating a number
of different scientific
questions.
Two of them are the things we've
already talked about today.
What is the solar wind?
How is it accelerated to
these supersonic speeds?
What makes all the
structure within it?
And then, the related
question is lower down.
Why was the corona so
hot in the first place?
What are the dynamics that
are creating all of that heat?
And again, we know it's
the magnetic field.
But exactly how is that
energy being dissipated?
Why does it dissipate
in a chunky way, as
opposed to smooth?
All of those different things?
Why does it dissipate at
the time that it does?
Why does it build
up a certain amount?
So, those are all questions
that Parker Solar Probe is
answering just by nature
of it being closer and
seeing that plasma,
that magnetic field before
it has time to evolve
on its four-day adventure
to the earth.
So, some of the instruments that
we're using to look at this.
The wide field imager
for a solar probe.
It's an imager.
It's one of those heliophysic,
heliospheric imagers.
So, it looks in white light.
But it's looking
off at the side.
And it's really more
like a microscope,
as opposed to a telescope.
Because we're right there
looking at the white light
in the solar wind right
before we fly through it.
There's a magnetic
field experiment
that measures the magnetic
field and the electric fields,
and some of the waves that are
in the plasma as
we fly through it.
And then, there's the
solar wind electrons,
alphas and protons, SWEAP.
This set of instruments.
So, alpha particles.
That's another name for helium
that has lost it's electrons.
So, that's what alpha
particles are.
But by measuring the electrons,
the protons and the alphas,
again up close to the sun, right
after they were accelerated,
you really can understand some
of the physical processes
before they've been affected
by other physical processes on,
in route on the way to earth.
So, this is a simulation
of some of the.
This is the field
of view of what
that white light imager will see
because it's getting so close
and it might see one of those
coronal mass ejections right
up close, kind of like
with a microscope.
Here's another.
These are the existing
coronagraphs that we have.
And then, here's again,
the Parker Solar
Probe getting close.
And then, looking at a
microscope through all
of these structures as
they, as they explode
and [inaudible] outwards.
So, I can show you today
two of the, or three.
There are three things up here.
Three of the first light
results that we had
from Parker Solar Probe.
Solar Probe has now had
three passes around the sun.
It's interesting when
the, we can't talk
to Parker Solar Probe very
well during its encounter
because it's so close
to the sun.
And in some cases, it's
behind the sun relative to us.
So, we actually have to
wait to later in it's orbit
when it comes back around to
actually pull the data down.
So, here's those images
from those imagers.
This is actually the
Milky Way is in the field
of view of those imagers.
So, you're seeing
the Milky Way here.
And then, here is some
of that complex structure
in the solar corona in, as it's
becoming the solar wind and sort
of viewing it up close.
And then, this is one of the
particle measurements of just
that normal, that plain
old solar wind plasma.
But here it is flying out at
400 kilometers per second.
So, that's what you're seeing
here is these, the red indicates
that we're seeing those
plasma measurements.
Now, expect to hear in the
next maybe month or so some
of the big announcements
from what Parker Solar
Probe has actually seen.
Like I said, it took a while for
the data to actually come back.
And then, for the
scientists, of course,
to understand what they meant
since we've never
seen the plasma
in this environment before.
[ Inaudible question ]
No. So, this is the Milky Way.
The dots here are other stars.
I believe there are
planets in here.
But I can't be positive
which ones.
And I believe that
that's a planet.
But I don't remember which one.
Yeah, the sun.
So, in both of these
images, the sun is way.
[Inaudible].
Yeah. And so, these are imagers
that look off to the side.
So, Parker Solar Probe, as
I said, had three orbits.
It's about to do
another Venus flyby.
And so, then, we'll
get new kind of data,
as it gets in the next
step closer to the sun.
So, that'll be really cool.
And we're really
excited by that.
So, the takeaway that
hopefully I've convinced you
of is there are no
quiet days on the sun.
Even during it's
most quiescing time,
the solar atmosphere is still
filled with waves, explosions,
little explosions,
big explosions,
energy bursts, structures.
This launches dynamic plasma
out into our whole solar system.
And this dynamic solar wind
is constantly bombarding all
of the planets, including
us, including the earth.
So, that's really important
for us here at earth.
But it's important for the
other planetary systems as well.
And it creates this
dynamic space environment
that we live in,
even on a normal day.
Thank you.
[ Applause ]
>> Stephanie Marcus:
Thank you, Nicky.
And now, we can take questions.
And she will repeat them,
so everyone can hear.
Please ask your questions.
>> Nicholeen Viall: Yes.
>> You used the word
chunky, which I really liked.
>> Nicholeen Viall: Yes.
>> I'm just wondering
if [inaudible] sort
of big picture way,
should we expect
that the sun is more uniform
and that [inaudible] is
sort of the exception?
Or should we expect
that it's more chaotic
and that the uniformity
is kind of the unexpected?
>> Nicholeen Viall: The expected
relative to other stars?
Or relative to the
sun's lifetime?
Or relative?
[Inaudible].
Yeah. So, well yeah
that's a whole,
we could have a whole
discussion about that.
Magnetic explosions.
We also call those
magnetic reconnection.
Seems to be inherently chunky.
It seems to be.
It doesn't just happen
in a laminar fashion.
It sort of goes in bursts.
So, kind of wherever
you look in the universe
where magnetic reconnection
is occurring, that does sort
of seem to be bursty
or chunky or pieces
of sort of restructure.
So, that seems to be
a universal thing.
Waves, which will interact
with different kinds
of plasma differently.
Like, it might find a
resonates over here.
And so, it'll only focus
it's energy right here.
But it won't find a
resonates over here.
And so, it kind of
just passes through.
So, that'll be something that
will tend to create structure.
So, I think, yeah, structure
and, and, and chunkiness,
burstiness, it's probably
a universal feature.
The other thing is what's
controlling these dynamics is
the magnetic field.
The magnetic field on
the sun, certainly.
And we know that this is
true on other stars too.
Goes through a solar cycle.
So, the magnetic
field builds up.
It has more of those
active regions.
Those regions of intense x-ray
and ultraviolet radiation
that are associated
with the sunspots.
Gets more intense, more
intense for 11 years.
And then, we reach maximum.
And then, it goes away.
And then, the polarity
flips on the sun
and the whole cycle starts over.
But with the reversed polarity.
So, that's the really
long scale.
But that magnetic field
and how intense it is.
And how it's trying to
restructure itself is going
to be part of the story.
And so, stars with different
kinds of magnetic fields
or more active magnetic
fields will maybe have more
or less of that.
Yes.
>> So, when I was looking
at the pictures of the sun
and it was rotating, it looked
like there were two bands
of like major activity.
And I was wondering [inaudible]
if that was actually
happening [inaudible]?
>> Nicholeen Viall: So,
the bands on the sun in.
I'm going to see if I
can pull this back up.
[ Inaudible ]
So, when we were looking at
the video in 171 angstroms,
which is sensitive to a little
less than a megakelvin plasma
and there were different bands.
So, we're seeing, I think.
Ah, let's see if I
can get back there.
Eventually.
Here it is.
Next one.
Poof. Here we go.
Alright. [Music].
These bands.
So, there are definitely
bands of activity on here.
There's active regions, which
are these intense regions
of ultraviolet light
that are associated
with the magnetic field,
concentrations on the sunspots.
There are also these dark bands.
Those are filaments.
They look dark on disk in
this particular wavelength.
But off the limb in
that cooler wavelength,
you would see those
filaments glow in red.
They have cool material.
Those are locations where a lot
of magnetic field
stress has built up.
Sometimes those erupt
actually and are one way
that we can get coronal
mass ejections.
So, yeah, there's definitely
bands of activity that persist
for several solar rotations,
both in terms of filaments
and also the active
region locations.
>> And is there more going
on around the equator
versus the [inaudible]
what we're seeing.
>> Nicholeen Viall: Both.
There is an equator.
Because the sun rotates.
So, that does sort of set
a mid, like pulls in a mid.
And the magnetic field does
organize itself around that.
Because of the solar dynamo.
So, there is an equator.
And the active regions, those
active polarity spots do pop
up on either side of that with
certain polarities depending
on where it is relative
to the equator.
And your question
about the pole.
Does the pole have
more or less activity?
Or can we just not see it?
And the answer is
yes to both of those.
It is hard to tell for sure
what is going on over the poles
because we're here at the
equator looking far away.
So, going over the poles
would be really cool to do.
There was a mission
called Ulysses
that flew over the poles.
But it only had in
situ instrumentation.
So, it has evidence about
what the poles look like.
But it doesn't, it didn't
have a imager to look.
So, that would be a cool thing.
So, yes, there are
definitely times where it looks
like the poles have a
different kind of activity
than what's going on
in the active regions.
You don't see active
regions, for example,
up at the top of the poles.
They sort of.
They pop up sort of here
at the midlatitudes.
And then as they, they advect,
actually they get
convected up to the poles.
And then, they kind
of dissipate.
We believe that actually
has to do
with how the next
solar cycle is setup.
Yes.
>> What's the heat tolerance
that Parker was built
to survive?
>> Nicholeen Viall: I don't
remember off the top of my head.
But yes, they definitely
did a lot of testing
of the heatshield to make sure.
You know, the requirements
are always
that we withstand x number more
than what we actually expect
the environment to be.
>> How many rotations will it
actually experience before it
hits the limit?
>> Nicholeen Viall: Yeah,
so 2024 might be our last,
our last orbit around the sun.
And what happens is we can't,
we run out of propulsion
to hold the heatshield in
front of us and the sun.
And so, that's when things
don't go well anymore.
[Laughter].
But that's part of the plan.
I mean, that's, you have to.
You can't carry infinite
propellants.
So, we have, I think I showed
it maybe in one of those movies.
We have many orbits.
We've already had three.
About every six months,
right now is the cadence.
But then, they go faster later.
Yeah, so we could
count these up.
That's how many orbits.
Each one of these blue guys
is an orbit around the sun.
So, we have.
The orbits, of course,
go faster as,
after we do the Venus flybys.
And we get closer.
So, we start to go
faster around the sun.
And then, we have more of them.
So, we have many, many orbits.
Now, we don't take data when
we're far away from the sun.
We only take data when we're
close to the sun mostly.
And that has to do with
the ability to talk
to the spacecraft and
bring those data down.
Yes.
>> The illustrations seemed
to depict the magnetosphere
as like a donut shape
around the earth.
>> Nicholeen Viall:
The Van Allen belts?
>> I guess so.
>> Nicholeen Viall: Yeah.
>> And so, part of
the [inaudible]
of the earth [inaudible]
much less protected.
>> Nicholeen Viall:
Oh, I'm not repeating.
>> Stephanie Marcus: I thought
you heard me [laughter].
>> Nicholeen Viall: The poles.
The.
>> Stephanie Marcus: I know.
Start over
>> Nicholeen Viall: Sorry.
Say, say it again.
Your questions please.
>> Are the poles less
protected by the magnetosphere?
>> Nicholeen Viall: Ah, yes.
Okay. So, are the
poles protected,
less protected by
the magnetosphere?
In some ways, yes.
So, these field lines
here over the equator,
shield us from the
plasma from the solar wind
and from these coronal
mass ejections.
These field lines here are
directly open to the solar wind
and connect to the
magnetic field
of the rest of the heliosphere.
And so, yes, there can
be some direct access
of energetic particles
over there.
In fact, when we have a big
storm, flights will be rerouted,
so that they don't fly
over the poles because of
that direct access
of the energetic
particles over the poles.
Yes.
>> So, it sounds like some
of the observation [inaudible]
helps us better understand other
stars up there.
Is the reverse true?
Like does that distance
sometimes help us understand our
own star better, maybe
about what's going
on at the poles [inaudible]
very well?
>> Nicholeen Viall: Yeah.
Yes. So, in general,
more datapoints,
more than one datapoint
about other systems is
always a good thing.
We get different
kinds of information
from the stellar observations.
But indeed, there are a
lot of sun like stars.
And even thinking about
like how the habitability
of those solar systems
around those stars is also
a piece of that story.
Yes, we get different kinds
of information from
the other stars.
And that helps us piece together
what our star maybe looked
like before, what it might
look like in the future.
How some of these
universal processes,
like the magnetic
field intensity,
and how those magnetic
fields make different kinds
of dynamics.
We can definitely
learn information
from looking at other stars.
Other questions.
Yes.
>> So, I saw a couple days
ago there was some reporting
about Voyager Two hitting
the, you know, the [inaudible]
with the extra solar system.
>> Nicholeen Viall: Yep.
>> Radiation coming in.
Did that yield something
of interest here,
in terms of the solar wind
and what it does [inaudible]
to the solar system?
>> Nicholeen Viall: It's,
it is generally related.
But not specifically related
to what we're looking at here.
The heliopause is where
Voyager, the Voyager's crossed.
So, just like there's
the magnetic field
of the earth carves out
a boundary around earth
because of the plasma
not crossing the magnetic
field lines.
And we call this
the magnetopause.
There's an equivalent much,
on a much larger
scale, the solar system.
So, now imagine this
wasn't the earth in here.
But imagine the sun in here.
And the sun's magnetic field.
And that this is the
interstellar plasma.
There's sort of an equivalent
bubble formed by the plasma
from the sun and the plasma.
The solar wind and
the magnetic fields
from the sun making
a plasma bubble.
The heliosphere and
the heliopause.
It's at about 100 AU.
So, one AU is the distance
between the earth and the sun.
So, 100 times that.
So, by then, the solar
wind is very diffuse.
It's been a lot of.
It's had a lot of processing.
So, in terms of helping us
understand it's formation,
it doesn't do so much of that.
But in terms of understanding
these fundamental plasma
processes and how magnetic
fields interact with the plasma,
it's definitely an
analogous sort of situation.
The interstellar medium might
be impacting our heliosphere
in a similar sort of way.
Yes.
[ Inaudible question ]
>> Nicholeen Viall: There's
actually a very steep
temperature gradient.
It's called the transition
region.
And it's this, this,
this location where.
It's more than six inches.
But it is pretty
steep, where it goes
from 6,000 is the
temperature of the photosphere.
There is a layer above that
called the chromosphere.
And the chromosphere is 10's of
thousand, 10, 20, 30,000 kelvin.
So, it's a little bit hotter.
But then, between the
chromosphere and the corona,
there, there is a thing
transition region where all
of a sudden, the plasma goes
from 100 kelvin to 200 kelvin,
200,000 kelvin, up to
a million very rapidly.
But we can see the, that
there is plasma on the way.
That there is plasma
at 100,000 kelvin.
And there is a little
bit of plasma
at 200,000 all the way up.
So, we can measure
that transition.
[Inaudible].
They are in an equilibrium.
So, the, you can work out
the hydrostatic equilibrium
equations actually
for the solar corona.
And because of this
magnetic connection back
to the chromosphere, the plasma
in the corona will emit some
of that energy out as radiation.
And then, it actually
thermally conducts some
of that energy back down
into the chromosphere,
which is very, very dense.
And so, it will radiate some
of that energy away
through light too.
>> I have a quick question.
So, what is Parker Probe, the
Parker's Probe fate once the,
it's just going to burn up and?
>> Nicholeen Viall: Yeah.
[Laughter].
What is Parker Solar
Probe's fate?
It might just burn up.
Yeah, it's.
>> Once the heat
shields are down.
>> Nicholeen Viall:
By design, it.
You know, of course, we keep
taking data as long as we can.
But, but by design, it has a
certain amount of propulsion
to hold that heat shield.
And then, when it runs out,
then that's, that's it.
>> It just burns up?
>> Nicholeen Viall: Yep.
And we should have another one.
And then, and then,
we could see more.
>> Where is the Solar
Observatory located?
Is it terrestrial?
>> Nicholeen Viall: Which?
I showed many, many
solar observe.
Solar Dynamics Observatory?
The Solar Dynamics
Observatory was one
of the spacecraft that I showed.
That one is also in a
LEO orbit, I believe.
So, it orbits the earth
and looks at the sun.
The STEREO spacecraft.
It's called STEREO because
actually there are two of them,
so that they can look
at stereoscopic views
and get 3D information about
the coronal mass ejections.
I didn't highlight that aspect.
But STEREO is in very
similar orbits to the earth.
But ones slightly
ahead of the earth
and ones slightly
behind of the earth.
And then, they slowly go
around relative to us.
And then, our, we have
spacecraft, other observatories
that sit just upstream
of the magnetosphere,
so that we can see stuff.
Sort of think of it like
those tsunami buoys.
Like you see the stuff
right before it hits.
So, you get a warning
in that sense.
And then, we have a whole
bunch of spacecraft that sit
and orbit the earth
in the magnetosphere.
Yes.
>> So, is there any relationship
between the degradation
[inaudible] atmosphere
and it's possible effect
on the magnetic field?
Or are they completely
separate and distinct?
>> Nicholeen Viall:
Yeah, the magnetic field
of the earth is set
deep down in.
The earth has it's own dynamo
that creates the magnetic field.
So, that's definitely
an independent process
from atmospheric things
going on, on the earth.
Yeah.
>> Stephanie Marcus:
Thank you all for coming.
[Multiple speakers].
>> About Parker.
>> Nicholeen Viall: Sure.
>> Why does, why does it,
why couldn't it just go
around the sun at
a close distance?
Why does it have to
keep going around Venus?
And it seems you could
get a lot more data.
>> Nicholeen Viall:
So, we start off going
at the earth's velocity
when we launch a spacecraft.
The spacecraft is
traveling with the earth.
So, it's going with
the earth's velocity,
which means actually it starts
off at the orbit of the earth.
Because how fast you go is how
far, how far away you orbit.
So, you actually have to
go the opposite direction.
You have to get delta
velocity, a change in velocity.
You have to get rid of velocity.
So, we use Venus to get
rid of the velocity.
Actually, some of the original
ideas were to go out to Jupiter
and use the gravity of
Jupiter to get even closer.
But there were some pros
and cons of that approach.
So, the Venus approach is
the one they went with.
But you got to get rid of
a lot of velocity to spiral
into the sun is the key point.
>> Stephanie Marcus:
Thank you all for coming.
>> Nicholeen Viall: Thank you.
>> Stephanie Marcus:
And thank you.
[Applause].