Translator: Gisela Giardino Reviewer: Sebastian Betti
Many years ago the Star Trek series
began each episode with the phrase: "Space: the final frontier."
The main starship, the Enterprise,
had the mission of exploring strange new worlds
to reach unknown places nobody had never arrived before.
While the original series it's a bit old, I still love it,
because in each episode they actually find new worlds.
And they challenge what they knew until that very moment.
I always found incredible the chance to make those discoveries.
The question: "Are there other worlds outside the solar system?",
is a question we always had.
It's of the oldest questions of humanity.
The Star Trek exploration was science fiction by then.
But today it's ceasing to be thay way.
When I became interested in astronomy
we only knew planets in our solar system.
But today we live in unique times.
Because for the first time in history
we know that other planets exist around stars that are not the Sun.
The first planet outside our solar system
was found a little over 20 years ago.
And it was the beginning of a true revolution in astronomy.
Today we can spot on our galaxy map
more than 3000 planets around other stars.
Planets that are outside our solar system or "exoplanets", as we call them.
And the count continues.
We know that the star that is closer to our solar system
is only four light years away and it has a planet around it.
And the farthest planet we know of is 27,000 light years away.
That means that if we sent a WhatsApp message to an imaginary friend
who lives on that planet we would have to wait 54,000 years
to find out they left in on seen.
(Laughter)
And, yes, it's true.
We don't have an Enterprise ship to take us there yet.
But we do have the technology that lets us discover and explore them.
I am an astronomer
and I belong to this new generation of space explorers.
I'm in the scientific team of two space missions.
I'm on NASA's Juno mission,
which right now is around Jupiter
changing our knowledge of that planet.
And I'm also on the scientific team of the Ariel mission,
from the European Space Agency,
which is a space telescope that we expect in 10 years
to be watching the atmospheres of exoplanets with.
My work is like trying to put together a jigsaw puzzle
having just a couple of pieces.
I want to know what these planets are like,
how they were formed, how they evolved.
And for that I study their atmospheres and their insides.
I take the few observations that we have available
and with those bits of information I think up how these planets would be
from a physical and chemical standpoint.
Then, I design computer models to create simulations
to show me how these planets that we are finding might be.
And the truth is that it took us a lot to find the first exoplanets.
In the 1990s we just found them.
That's because finding exoplanets is super difficult.
Stars have a light so much brighter than that of planets.
They dazzle us and don't let us see what they have around them.
To give you an idea, imagine a lighthouse 6 miles away.
What we want to find is a firefly right next to that lighthouse.
Finding exoplanets is that difficult.
But we are finding them.
We are studying them.
And it's not science fiction, but reality.
And as it happened in Star Trek every time they found a new world,
each new exoplanet pushes the frontiers of our knowledge.
Today, we know that there are really crazy planets.
Planets that could have come out of a science fiction work.
There are so many out there, that even the strangest ones you may imagine
possibly exist.
We were able to observe newborn planets, baby planets,
or very young planets like these you are looking at now.
When planets are young,
they still have heat left from their creation
and that's why they shine more brightly and it's easier to detect them directly.
On the other end, as well, we find very old planets.
Planets almost as old as the universe.
This one you are seeing here is called Methuselah
and we believe it to have 12.5 billion years.
That's almost three times the age of our planet.
Of course, that planet doesn't shine as much as the young planets,
so we don't have a real image like the one I showed you before,
but I am showing you an artistic representation
of what that exoplanet would look like.
We also find exoplanets around binary or multiple stars.
That is, a planet that has two or more suns.
We find planets around dead stars.
Stars very different from our sun.
Places we didn't think possible to have planets.
And the next ones now are my favorites,
because I was studying their atmospheres.
They are rocky planets like ours,
but they are very different from our planet in fact,
because they are super close to its central star.
So close that they have temperatures of more than 2000 ºC on the surface.
So at that temperature their surface is an ocean of lava that evaporates
and forms an atmosphere of vaporized rocks.
Imagine: just like it rains water here, on those planets it rains rocks.
So extreme are the planets we are finding.
The exoplanets challenge us all the time.
The first ones we found already put us to the test.
Think of our solar system where we have the Sun,
which is a pretty normal middle-aged star.
The planets that are closest to the Sun are the rocky planets.
Those in which we can stand on the surface.
And those who are much further away are the giant planets.
It's easy and logical: the rocky planets are closer to the star,
and the giants, farther.
For centuries we thought that this was the normal structure
for a planetary system and we built models
to explain and sustain this.
Until the first exoplanets appeared.
Especially, the first one that we found
around a star similar to the Sun.
That planet is called Dimidium and it's pretty similar to Jupiter --
nothing weird there --
but it is seven times closer to its central star
than Mercury to the Sun.
The truth is that we were not prepared for that discovery.
Actually, the people who made the discovery
had to check everything several times before announcing it.
And that was not all.
We also found a new class of planets that we didn't know that existed.
Planets that we call super-Earths, or mini-Neptunes,
because they are so much bigger than our planet,
but not as big to be a giant planet.
It is an intermediate size that we don't have in our solar system,
and we didn't know it existed.
And these planets, apart from being a new class,
a new species that we didn't know of,
they make up for the vast majority of exoplanets that we are finding.
The truth is that I learned a lot of things in these years
of studying exoplanets.
I learned how to face the unknown.
What do you do when the information you receive
makes you question your own beliefs?
Dimidium and the super-Earths did that.
They forced us to change the paradigms,
to change the way of thinking we had until that moment.
I also learned that sometimes, to learn more about ourselves
we have to look very far away.
Studying exoplanets helps us understand a little more
about the formation our own solar system.
It helps us understand what creates the conditions for the origin of life,
and put our planet Earth in context within the universe.
And I also learned why this kind of research
is important to us all.
The huge technology we developed these past years
to study these exoplanets
pushed us to the limit of what we thought we were capable of doing.
And that is the great value of the studies in basic sciences.
They help us create new technology that in the long-term
is applied in unthinkable ways, helping to improve our quality of life.
Einstein was not thinking about the GPS
when he developed the Theory of Relativity a hundred years ago.
And yet that theory is fundamental
to have an accurate measurement of positions.
That is, for the map that we all have in our cell phones
and that we use every day.
And this is a very small example.
The life of all of us is affected by astronomy,
much more than we realize.
From the Big Bang, the formation of our planet,
the perfect distance between Earth and the Sun
so there is liquid water on the surface,
and so that all of us can be here.
To even more everyday things,
such as the seasons, the day and night cycle,
the way to measure time.
Think of the meteorite that made the dinosaurs go extinct.
And even more, that all of us are made of star dust.
The carbon in our DNA was generated inside a star.
And astronomy affects us in other ways as well.
It inspired generations of artists and it is present in the mythology
of all the ancient civilizations.
And it's us, the astronomers,
who are after the question that may alter the course of our history.
The Enterprise, that ship I told you about at the beginning,
had another mission besides exploring foreign new worlds:
It was also seeking out new life and new civilizations.
And now that we know that there are so many exoplanets out there
what we want to know is:
Are we alone in the universe?
To find signs of life in any of these exoplanets would be incredible.
And perhaps a little scary, too.
But it would also be wonderful, and definitely terrifying and lonely,
to think that we are the only ones in the vastness of the universe.
The next time you look at the stars, think about that question.
Finding the answer is our next step.
Thank you.
(Applause)