(soft music)
Sara Seager: When I see the stars, I think about how all of them are suns and how if our Sun has planets, it makes sense that those other stars have planets, also. Our galaxy alone, with its hundreds of billions of stars, probably has over a trillion planets. Numbers so vast we can barely comprehend them.
I am Professor Sara Seager at the Massachusetts Institute of Technology. I'm thrilled to be one of this year's winners of the Kavli Prize in Astrophysics. The large amount of work in exoplanets today is based on the foundation that I and my co-winner set down. My co-recipient, Dave Charbonneau, ended up getting the candidate and finding the first transiting exoplanet. But that enabled me to rush to finish my paper I'd already started on transit transmission spectroscopy. I'm so proud to have invented the main way we study exoplanet atmospheres today, transit transmission spectroscopy.
When the planet goes in front of the star, the starlight drops by a very characteristic amount related to the planet area to the star area. Now, if the planet has an atmosphere, the starlight drops by the area of the planet plus the area of the ring caused by the atmosphere. So, if we imagine measuring the planet at a wavelength where the atmosphere is fully transparent, we get a certain size. Now, if we measure an adjacent wavelength where the atmosphere is strongly absorbing, the planet looks a tiny bit bigger. And that's how we study exoplanet atmospheres.
In the search for signs of life on exoplanets, we're just simply looking for a gas that's way out of equilibrium in context with its environment, like oxygen here on Earth. We still have a long way to go. In the near term, it's just sorting through what exoplanets actually are using the transmission spectroscopy method with the James Webb Space Telescope. Longer term, I'm in love with Venus.
Venus is kind of like our evil twin sister. It has a massive greenhouse atmosphere, making the surface too hot for life of any kind. However, we're starting to think that maybe Carl Sagan's idea from half a century ago, that there might be life on Venus in the clouds where it's much cooler, could actually be realistic. So, that is my main focus right now.
(bright music)
In my heart, and what I've dedicated the rest of my life to, is finding a true Earth twin. A planet that's about Earth's size, about Earth's mass, orbiting a Sun-like star in an Earth-like orbit. And the transit transmission spectra probably can't be used because the Earth atmosphere compared to the backdrop of a Sun-like star is just too tiny.
Instead, we'll need a special sophisticated space telescope. The telescope will be what we call 'starshade ready'. A starshade looks like a huge flower with petals. Starshade will block out the starlight.
So, only planet light enters the telescope. It has such huge, wonderful capability to study the atmospheres of Earth-like worlds. As humans, we desire to understand what else is out there in that vast night sky.
And because of today's tools, we're able to reframe that question as are there other earths? Do they have signs of life? And can we identify any habitable or inhabited worlds?
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This work was produced by Scientific American Custom Media and made possible through the support of The Kavli Prize.
Explore more about the work of the 2024 Kavli Prize winners in two podcasts, Building Materials From The Bottom Up and How Our Brains See Faces.
