What the Discovery of Exoplanets Reveals About the Universe | Jessie Christiansen | TED

I am a planet hunter

and keeper of the keys at NASA's Exoplanet Archive.

In March 2022, we reached a major milestone in space exploration:

5,000 known exoplanets.

For thousands of years,

we've wondered about planets outside of our solar system,

now called exoplanets.

But our technology only recently caught up with our imaginations.

And yes, 5,000 planets is incredible.

What's even more incredible

is how space research will change as a result.

When I started grad school,

there were about 100 known exoplanets,

all radically different from the Earth and from each other.

I was determined to find more.

I spent four years looking at nearly 87,000 stars, one by one.

Now you might have this romantic idea

that I was gazing intently through a telescope,

pondering some gorgeous view of the universe.

I was not.

I was looking at data like this,

measuring the brightness of each star over time.

If the brightness dipped, just briefly, just a little bit,

it could be because a planet had orbited in front of that star,

blocking some of the light from reaching my telescope.

So I spent four years looking for decimal-level changes in these data.

And after four years, I'd found ...

nothing.

Zero exoplanets.

Thankfully, they still gave me the PhD, I think, for effort.

(Laughter)

Then I moved to Harvard, where I worked on my first NASA mission, called EPOXI.

I still didn't find any exoplanets.

Then in March 2010, I joined the Kepler Mission,

NASA's grand experiment

with putting one of our planet-hunting instruments into space.

Monday was my first day on the base in Silicon Valley.

It was mostly spent in HR.

Tuesday, I sat down and looked at the data for the first time,

and I found my first exoplanet.

(Cheers)

(Applause)

A few minutes later, I found another one.

There's a saying that we're the generation that was born too late to explore Earth

and too soon to explore space.

That's not true anymore.

That day and every day since, I've gotten to explore space.

Kepler made it possible for us

to measure stellar brightness much more precisely

than we had before.

And eventually I helped find thousands of exoplanets.

And we've really only searched our local corner of the galaxy

to find those planets.

That means there's likely tens of billions of planets just in our Milky Way.

Now with so much data,

we can start sorting and grouping and categorizing these planets

to find trends.

Think of it this way:

if you wanted to learn about dogs and you had five dogs in your study,

well, you'd learn a lot about those five dogs.

That they're all good dogs.

But maybe not about dogs in general.

If you had 5,000 dogs in your study,

then you’d start to see that there were German Shepherds and Dobermanns

and beagles,

and that these different breeds have different features.

With demographic-level data on exoplanets,

we can start asking some of these big questions for the first time,

like: Of those thousands and billions of planets in our galaxy,

how many are like the Earth, or like Jupiter?

How many planets does a typical star have?

Can a planet orbit more than one star?

Yes.

Can a planet exist without any star at all?

Also yes.

One surprising result from the study of planet populations

is that the most common kind of planet in our galaxy

might be one we don’t have in our solar system:

a super-Earth up to twice as big and ten times as heavy as our Earth.

We've found evaporating planets, disintegrating planets,

planets clustered together in a clockwork dance,

ultra-puffy planets, ultra-dense planets.

It's truly a wild and wonderful menagerie

that I get to corral at the NASA Exoplanet Archive.

But it gets even more interesting than that.

With so much data, we might finally be able

to figure out how planets are made.

We see baby stars being born in stellar nurseries

surrounded by dust and gas.

And we see all the stars surrounded by completed planetary systems.

But we still don't really know what happens in between.

With more data, we might find planets

at some middle stage or many middle stages.

And from there, be able to map out a timeline of planetary development.

What triggers these diffused clouds of dust and gas to collapse and transform?

And how does the chaos and turmoil of dust become pebbles,

and pebbles become boulders, and boulders become planetesimals?

And from there,

after an intense series of bombardments

eventually settle into an ordered series of planets.

How often is one of those planets solid and warm,

with a water ocean lapping a sandy shore?

Where do we come from, and how did we get here?

The more we learn about exoplanets,

the easier it is to target the ones we want.

So far, we haven't found any planets that are like the Earth.

But I hope we will.

NASA just spent the last few years

studying the idea of a very large telescope in space

with next-generation technology that would allow us to take an image,

an actual photograph, of a planet like the Earth.

With that photo, we could search for biomarkers, signatures of life.

I'll probably spend the rest of my career working on that mission.

I hope I get to take that photo.

Thank you.

(Applause)