Transcriber: Rhea Tsania Reviewer: David DeRuwe
There is a dim red star, not very far from us.
Around this star, is a planet.
I imagine myself standing on this planet.
I’m feeling heavy, so the gravity here is strong.
The sky is dark and red,
but strangely enough, the temperature feels quite comfortable.
I may be able to hear an ocean in the distance.
Welcome to LHS 1140b.
LHS 1140b is a planet,
around a star other than our Sun.
It is an exoplanet.
I helped to discover LHS 1140b.
In fact, I've helped to discover more than 70 other exoplanets.
I have a confession to make; I am not a professional astronomer.
I don't have a big telescope.
I did all this from an observatory I built,
in the backyard of my home,
in the suburbs of Perth, right here in Western Australia.
20 years ago, through my very first telescope, I looked up,
I saw sunlight glinting off the rings of Saturn.
I saw the cloud tops of Jupiter.
These are wondrous, wondrous sights, and they’re bright,
but I quickly ran out of bright things to look at.
I started to take photographs through my telescope,
and I actually got quite good at it.
But then I started to wonder.
Could I do more?
Could I discover supernovae?
Supernovae are exploding stars.
For a brief, glorious moment they can shine with the light of a trillion suns,
but they are rare.
So I started a supernova search
from behind my kitchen.
(Laughter)
My telescope couldn't really point very well,
and to have any chance of success at all,
I had to look at hundreds of targets each night.
So instead of getting the telescope to chase after targets,
I let the night sky as it rises, bring targets up to the telescope.
I wrote software, so that I could efficiently check through
hundreds and hundreds of images that came from the telescope each night.
You know what?
It worked,
and I discovered three supernovae in as many years.
This was my first discovery back in 2007.
The supernova is that star in the crosshairs.
That supernova is more than 200 million light years away.
I discovered a supernova.
I love it when a plan comes together.
(Laughter)
By 2010, a few exoplanets had been discovered.
Now, to understand how you can detect an exoplanet,
imagine you’re an alien out in the stars,
you’re looking at our Sun.
If you’re in the right direction, from time to time,
you will see a planet cross the face of our Sun,
dimming its light by a tiny, tiny amount.
That is really hard to detect.
So I thought, “Could I discover an exoplanet?”
(Laughter)
LHS 1140b star is a thousand times dimmer
than the dimmest star that you can see with the naked eye.
It’s like a candle placed 400 kilometers away.
Now, imagine a grain of sand crosses the front of that candle flame,
dimming its light by five parts in a thousand.
Just five parts in a thousand.
That is what I set out to detect.
(Laughter)
So I built,
(Laughter)
the PEST,
the Perth Exoplanet Survey Telescope.
It is an off-the-shelf telescope in a plywood box in my backyard.
Of course, what you don't see,
the observing techniques and the software,
a lot of which I had to adapt or write.
I did the math, and I use that to guide how I observe,
and the more light that you can detect, the more precisely you can measure.
So I wrote software that takes light from the many stars in each image
and used that to improve my measurements.
I hope you can understand that when I started out, I had a concern.
If I made a detection, why would any professional astronomer believe me?
So I deliberately set out to make myself known,
by posting high-quality observations online.
There are many steps in confirming a discovery,
some of which do require seriously huge telescopes.
So I work in a team called TFOP,
the TESS Follow-Up Observing Program.
It’s a team run by NASA and MIT
to support the TESS Space Telescope.
TESS is surveying the whole sky to discover exoplanets.
So far, it has confirmed the discovery of about 130 planets,
and I’m very proud to say that I’ve had a part in about a fifth of those.
There will be many, many more,
because TESS has already identified
more than 3000 other possible planets.
Now what sort of planets have I helped to discover?
It turns out that exoplanets
can be seriously weird.
Imagine, a planet so puffy that it has the density of Styrofoam.
I imagine this planet rolling down the street blown by the wind.
Or a planet that has two suns, kind of like Tatooine in Star Wars.
Or an ex-giant planet that has had its outer layers blown off,
leaving only the naked core.
But the planets that really excite us are the small rocky ones
about the size of Earth because if a planet gets too big,
it tends to draw in so much gas that it becomes a gas planet.
About the temperature of Earth, such that liquid water can exist.
Why?
Because life, as we know it, can only exist
if liquid water can exist.
So our search for exoplanets really is a search for life out there.
All around us is air.
In that air, there is about 20% oxygen.
That oxygen actually shouldn’t be there.
That oxygen would not be there if life on Earth did not replenish it;
it would quickly react away.
Very soon, NASA will launch the James Webb Space Telescope.
It will look at exoplanets, such as LHS 1140b,
to try to look for signs of life.
I am looking forward to the day when the message comes,
“We have found a gas that shouldn’t be there
in the atmosphere of LHS 1140b.”
Perhaps that will be the day that we begin to realize,
that we are not quite alone.
When I was six, I watched the Apollo 11 moon landings.
I was inspired, I wanted to look into space, so I thought,
“Could I build a telescope?”
Dad wanted to help, so he invited the town optician over.
The man came, he looked at my drawings and calculations and said,
“It can’t be done.”
The next time somebody tells you it can't be done,
I hope you show them how it can.
Thank you.
(Applause)