Dr. Sara Seager

And my original field of exoplanets and specifically exoplanet atmospheres got very mature.

And there's a lot of amazing young people and even now people not so young doing a fantastic job there.

And I try to not do things that other people can also do.

So that's one reason.

I do still work on exoplanets, but something happened, something pretty serious, actually, which gave me pause.

And that is that myself and now a growing number of others, my heart, my whole heart is in wanting to find signs of life on other planets.

But we had a little glitch.

And this glitch is how sure can we be that we have found signs of life by way of a gas in an atmosphere that doesn't belong?

Here on Earth, we have oxygen, which fills our atmosphere to 20% by volume.

But without life, without plants and photosynthetic bacteria, we would have no oxygen.

And, you know, astronomers first thought of this 100 years ago, that maybe we should look for oxygen on other planets.

And they did.

They looked on Venus and they looked in other places.

And today we're there.

We have the James Webb Space Telescope.

The field that I founded, Exoplanet Atmospheres, is booming now and there's thousands of people working on it.

And just to make a very long story short,

I was here at MIT making a list of all possible molecules that could be considered a sign of life, a biosignature gas on an exoplanet.

And one of the molecules that jumped out as my favorite is called phosphine.

It's a phosphorus atom tied to three hydrogen atoms, something that on Earth pretty much only exists because of life, us humans making it as pesticides or bacteria in oxygen-free environments.