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I am a planetary astrophysicist.

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(Cheers) (Applause)

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Thank you.

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

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(Laughter)

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

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So I got my PhD in astrophysics

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

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

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

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

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

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or exoplanet, was discovered.

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

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and today there are
3,593 known exoplanets.

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(Whoo!)

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It's a lot.

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

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

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(Laughter)

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

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has been around for thousands of years.

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It is the oldest of the natural sciences.

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So today we're only just learning

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

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There are some planets
that actually share a star,

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so they have two stars over the same one.

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

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

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The Earth's period is 365 days.

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So that's pretty nuts.

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So we're only just now
really beginning to understand

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all the weird physical
and geometric properties

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that exist between a star and a planet.

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

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with respect to one another.

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I study how they chemically interact.

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But let me explain.

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

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

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There's none of that.

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So what happened
was that the Big Bang went off,

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

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But it did so in an uneven way

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until it formed
these giant pockets of gas,

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

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Eventually this gas collapsed
in on itself and formed stars.

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

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They were about a thousand times
bigger than the Sun.

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(Laughter)

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

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(Laughter)

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Except less furry.

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

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high enough temperatures
and densities that you had fusion.

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

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So you have hydrogen,
which has one proton,

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and helium, which has two protons,

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and they slam together,
and suddenly you have lithium,

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and then beryllium, and then carbon.

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

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so they exploded out everywhere.

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

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and they shot them out,
also into the universe.

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

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but also with these seeds of carbon

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that they could continue
the process of fusion.

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Our Periodic Table
was compiled by looking at stars

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who lived and died at different times.

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

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and what she did was she color-coded it

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

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

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but most of them come

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from either two stars circling
each other and then exploding,

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or just one exploding as a supernova.

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

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but also out of many of these elements.

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

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So that's everything
from Mercury to Neptune,

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even the dwarf Pluto.

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But it was on the Earth
that life blossomed,

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and out of that life came humanity.

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

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

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

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

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And we walk on iron silicates
on the ground,

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and we breathe oxygen,

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like right now, you're breathing,

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I could see it.

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(Laughter)

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That came from a star.

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So we're all stardust.

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Quite literally.

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

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in that we can create other elements.

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[Tennessine]

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(Applause) (Cheers)

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

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

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

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I'm often asked the question:

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"How can you look into outer space

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when there are so many
problems here on Earth?

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Doesn't it make you feel small?"

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And my answer to that
question is always no.

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

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

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that might have happened,

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

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

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

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or the stellar nursery.

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

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And it's by using the scientific method

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that we're able to come up
with a hypothesis

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

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

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4.6 billion years ago
as the solar system was forming.

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

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such that we can understand
their basic properties.

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

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and also at the bottom of the ocean,

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that could have only come
from a supernova.

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

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we're able to deduce the fact

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that this supernova
must have acted like a huge blender.

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

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and it swirled it together
until it made something

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that was palatable
or habitable for life.

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It's by looking at thousands of planets

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and millions of stars

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

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in order to create a planet
that could sustain life.

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Then there were even more unique
circumstances that were needed

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to create that life.

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In other words, we are
a mathematical anomaly,

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a rarity in the universe.

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And while there's probably
life in the universe,

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maybe even our Milky Way galaxy,

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that life is going to be inherently
different from our own

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

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

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

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So thinking about the statistical
likelihood of our existence,

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it doesn't make me feel small,

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

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

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and we'd look up at stars.

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And I'd look up at Orion in particular.

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

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

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

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it's like shells.

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So over time, I realize
that these constellations

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

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

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and they shone in different colors,

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and they were rotating
at different speeds.

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Some of them had planets
that were so close to them

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that it was hard to fathom.

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And others shared their planet
with another star.

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When you look up in the sky,

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

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Except, instead of seeing
data or pictures,

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you're seeing questions and possibilities.

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Regularly looking outside of our world

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

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There were so many events
that had to happen

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

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

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

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Realizing the statistical odds
of our existence,

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

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anxieties, and insecurities
just fall away.

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It reminds you who you are.

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

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

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how they formed and how they evolved.

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And maybe, just maybe, to discover life.

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But you don't have to be
a planetary astrophysicist

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in order to feel inspired
or empowered by outer space.

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

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outside of the right here
and the right now.

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There's stars being born,

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planets colliding,

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galaxies rotating,

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all of which are beautiful
as you can see.

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And they have nothing to do with you.

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(Laughter)

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Or so you think.

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But these were the exact events
that had to happen

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in order for the Milky Way
galaxy to be formed,

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for a supernova to go off,

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for the Earth to rotate around the Sun,

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and for us to exist.

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Thank you.

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(Applause) (Cheers)