I am a planetary astrophysicist.

(Cheers) (Applause)

Thank you.

But I will be the first to tell you
that I made that title up.

(Laughter)

You see, I had to make up a title
to describe what it is that I do.

So I got my PhD in astrophysics

because I look at the properties of stars
that are near to the Sun.

But I also look at planets and how
those planets and stars interact.

You see, up until about 25 years ago,
the term "planetary scientist"

meant only people who studied the planets
within our own solar system.

But it was in 1992 that the first planet
outside of our solar system,

or exoplanet, was discovered.

So, there's no name for somebody
who studies what I study,

and today there are
3,593 known exoplanets.

(Whoo!)

It's a lot.

So this field that I'm in,
it is very young.

If it was a person, it would
barely be old enough to drink.

(Laughter)

Whereas astronomy in general,
which is the study of celestial bodies,

has been around for thousands of years.

It is the oldest of the natural sciences.

So today we're only just learning

about all the crazy possible planets
that can exist out there.

There are some planets
that actually share a star,

so they have two stars over the same one.

And there are some,
like what you see on this picture,

that are so close to their planet
that they have a period of ten hours.

The Earth's period is 365 days.

So that's pretty nuts.

So we're only just now
really beginning to understand

all the weird physical
and geometric properties

that exist between a star and a planet.

But I don't look at just how
a star and a planet move

with respect to one another.

I study how they chemically interact.

But let me explain.

From the Big Bang, the only elements
that we got were hydrogen and helium.

So there is none of these
carbon or oxygen or iron.

There's none of that.

So what happened
was that the Big Bang went off,

and there was hydrogen and helium
shot all over the universe.

But it did so in an uneven way

until it formed
these giant pockets of gas,

which is sort of what you're
seeing in this video.

Eventually this gas collapsed
in on itself and formed stars.

But these stars were massive,
they were just absolutely huge.

They were about a thousand times
bigger than the Sun.

(Laughter)

So this is like saying our Sun is a grape,
and these massive stars were as a cat.

(Laughter)

Except less furry.

But it was within these first stars
that you were able to have

high enough temperatures
and densities that you had fusion.

So for the first time, elements were
slamming together, and they were sticking.

So you have hydrogen,
which has one proton,

and helium, which has two protons,

and they slam together,
and suddenly you have lithium,

and then beryllium, and then carbon.

But these first stars,
they lived hard and died young,

so they exploded out everywhere.

But they took all of these new elements
that they created inside of them,

and they shot them out,
also into the universe.

So a second generation of stars was formed
mostly out of hydrogen and helium,

but also with these seeds of carbon

that they could continue
the process of fusion.

Our Periodic Table
was compiled by looking at stars

who lived and died at different times.

This one here is color-coded and was done
by a colleague of mine, Jennifer Johnson,

and what she did was she color-coded it

to show the different ways
in which these elements could be formed.

So you see that a few of them are blue
because they came from the Big Bang,

but most of them come

from either two stars circling
each other and then exploding,

or just one exploding as a supernova.

So, our Sun is created out of the original
hydrogen and helium from the Big Bang,

but also out of many of these elements.

And at the same time that the Sun
was formed, were also planets.

So that's everything
from Mercury to Neptune,

even the dwarf Pluto.

But it was on the Earth
that life blossomed,

and out of that life came humanity.

But our humanity is really rooted
in the properties of our planet.

So when you think about it,
people are made up of raw ingredients,

these elements that are so basic to life,
which were created in stars.

We are carbon-based beings,
the bones made of calcium.

And we walk on iron silicates
on the ground,

and we breathe oxygen,

like right now, you're breathing,

I could see it.

(Laughter)

That came from a star.

So we're all stardust.

Quite literally.

But we can also do a thing
that is similar to other stars,

in that we can create other elements.

[Tennessine]

(Applause) (Cheers)

For example, tennessine,
which you may or may not have heard of.

So this is Ts 117, and it was named
after the great state of Tennessee

because a number of Vanderbilt scientists
were part of the discovery team.

I'm often asked the question:

"How can you look into outer space

when there are so many
problems here on Earth?

Doesn't it make you feel small?"

And my answer to that
question is always no.

It doesn't make me feel small,
it makes me feel empowered.

Because I know all of the things,
all of the events

that might have happened,

and all of the events that did happen
in order to create life.

You see, it's important for us as people
to know where we came from,

whether it's our parents, our ancestors,
our planet, the birth star,

or the stellar nursery.

Knowing our root is a fundamental drive
that is so important to humanity.

And it's by using the scientific method

that we're able to come up
with a hypothesis

that can explain how the solar system
got to be where it is today.

So for example, it's currently thought
that a supernova must have gone off

4.6 billion years ago
as the solar system was forming.

We're then able to collect data
about nearby stars and planets

such that we can understand
their basic properties.

So now we've found that there
are specific elements in meteorites,

and also at the bottom of the ocean,

that could have only come
from a supernova.

There, and with the help
of our peers reviewing our data,

we're able to deduce the fact

that this supernova
must have acted like a huge blender.

So it took the gas, and the dust,
and all of these new elements,

and it swirled it together
until it made something

that was palatable
or habitable for life.

It's by looking at thousands of planets

and millions of stars

that we're able to see what a unique
cocktail of basic elements was needed

in order to create a planet
that could sustain life.

Then there were even more unique
circumstances that were needed

to create that life.

In other words, we are
a mathematical anomaly,

a rarity in the universe.

And while there's probably
life in the universe,

maybe even our Milky Way galaxy,

that life is going to be inherently
different from our own

because they were affected by events
that never happened for us.

And it's going to take quite a lot
to actually detect that life

because we need to be able to find,
fund and develop the new technologies.

So thinking about the statistical
likelihood of our existence,

it doesn't make me feel small,

it reminds me of all the possibilities
that exist in outer space.

When we were undergrads, we'd walk
at night from the library to the dorm,

and we'd look up at stars.

And I'd look up at Orion in particular.

In our classes, we learned that two stars
that are shooting through space,

they're probably never going to collide,
no matter the circumstances.

And that the inside of a star
has a structure like an onion,

it's like shells.

So over time, I realize
that these constellations

changed from being just these dots
in the sky to being distinct characters.

I could see them, being
at different distances from us,

and they shone in different colors,

and they were rotating
at different speeds.

Some of them had planets
that were so close to them

that it was hard to fathom.

And others shared their planet
with another star.

When you look up in the sky,

it's like zooming from the Earth
into outer space.

Except, instead of seeing
data or pictures,

you're seeing questions and possibilities.

Regularly looking outside of our world

gives you a perspective
that's so easy to forget.

There were so many events
that had to happen

in exactly the right sequence
in order for me to be with you today.

If even one of those things was different,
say that the Earth was closer to the Sun,

or that the Moon didn't exist,
then maybe life wouldn't have happened.

Realizing the statistical odds
of our existence,

it helps to have
all of the day-to-day drama,

anxieties, and insecurities
just fall away.

It reminds you who you are.

A mathematical anomaly 
in a sea of gas, stars and planets.

And what I do is I study those stars
and planets in order to try to understand

how they formed and how they evolved.

And maybe, just maybe, to discover life.

But you don't have to be
a planetary astrophysicist

in order to feel inspired
or empowered by outer space.

All you need to do is look up and remember
that there are so many things going on

outside of the right here
and the right now.

There's stars being born,

planets colliding,

galaxies rotating,

all of which are beautiful
as you can see.

And they have nothing to do with you.

(Laughter)

Or so you think.

But these were the exact events
that had to happen

in order for the Milky Way
galaxy to be formed,

for a supernova to go off,

for the Earth to rotate around the Sun,

and for us to exist.

Thank you.

(Applause) (Cheers)