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You're listening to Short Wave from NPR.
Hello fellow Earthlings.
Regina Barber here, and today we're going to talk about some recent science news that made a big splash.
The claims that possible signs of life have been found on a planet called K2 -18b.
This made headlines everywhere, including NPR, where it was reported on by none other than our old pal, Nell Greenfield -Bois.
Hey Nell! Hey there!
So Nell, this was new research done with the James Webb Space Telescope.
And basically researchers said that they detected a couple of sulfur -based gases that on Earth are strongly associated with life, such as marine microbes.
That's right. Like phytoplankton.
So think alien phytoplankton.
The researcher said this planet could be an ocean world just teaming with life.
A press release called their results quote, the strongest evidence yet that life may exist on a planet outside our solar system.
Yeah, and all of this created like quite the uproar in astronomy circles.
I think some astronomers and planetary scientists were just taken aback at how all this landed in the public's eye.
Like I was talking with Ryan MacDonald.
He's at the University of Michigan.
For a lot of astronomers, the very first thing that we heard was like a message from a family member or a friend, oh, hey, have you heard that aliens have been found?
Spoiler alert, he and other astronomers do not think that aliens have been found.
And they have some real issues with how this whole thing went down.
Today on the show, what happens when a team of scientists claim to have found hints of alien life?
We look at what the researcher said, how everyone reacted, excited, and what all this means for the future of searching for life beyond our solar system.
You're listening to Short Wave, the science podcast from NPR.
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Okay, so now let's start out with just like some basics about planet K2 -18b.
like what is this place?
So it was discovered about a decade ago and not much is known so it orbits at a distance from its star that would make it kind of moderate in temperature so you know maybe liquid water is possible there.
This planet is bigger than Earth but smaller than Neptune and that means we don't really have anything like it in our solar system so no one really knows what it's like and some people think it could be entirely covered in water and ocean world other people say you know it could be covered in magma.
This is fascinating.
Okay, but how far away is this planet?
So 124 light years.
So that's far. It's far, yeah.
I mean in cosmic terms, maybe not, but yeah.
As far as human terms go, that's far away.
And the James Webb Space Telescope can't see the planet itself because the tiny amount of light it reflects is just overwhelmed by that of its closest star.
We can only find these planets because we can see their effect on the stars and all the telescope can see is light from that star.
So, when the planet goes around the star, it passes in front of it, getting between the star and the telescope, the starlight changes.
Some of the starlight interacts with its atmosphere, kind of filters through the atmosphere.
Yeah, so the idea is that you can analyze the starlight to get clues about the atmosphere and what gases are inside of it.
Exactly, yeah and the gases might tell you something about what's on the planet or what's going on there.
And so that's what this team of researchers tried to do.
And the work was led by Niku Madhusodhan.
He's at the University of Cambridge which held a press conference for reporters and he said what they'd found was just huge.
These are the first hints we're seeing of an alien world that is possibly inhabited.
I mean, that's a strong statement.
Like, what did they find?
Like, what were these hints?
Basically, he said when they analyzed the starlight They found signals that could come from two related sulfur -based gases, DMS and DMDS, and so these gases are found in Earth's atmosphere because they're produced by life, by microbes.
And because these gases on Earth are closely tied to microbes, they've long been seen as potential biosignatures, hints of life.
And these like sulfur -based gases aren't made by anything else?
Well, in the atmosphere, I mean, not that people are aware of that I know of.
I mean, there is some recent work in the laboratory showing that it is possible to produce these gases with no life.
We cannot, at this stage, make the claim that even if we detect DMS and DMDS that it is due to life.
Let me be very clear about that.
Okay. He said there needed to be more lab work and more modeling of possible things that could be going on on this planet that might make this stuff.
Like geologic processes or like something that didn't require life.
Yeah, and he also said the detection itself needed to be confirmed with more telescope observations to make sure that this gas or a combination of gases was really there you know.
But even though he made those cautious remarks, overall he was just extraordinarily enthusiastic.
Frankly I think this is the closest we have come to seeing like a feature that we can attribute to life.
And he said at a personal level it was like a shock to the system.
When you are faced with potentially one of the biggest landmarks in the history of science.
And I know this sounds grand and it's not my intention to make it sound grand, but there is no other way to put it.
Yeah. I mean, this would be a huge deal, not just in the history of science, but the history of humanity, but you said other astronomers were a little skeptical.
Yeah. I mean, it would be a huge deal if it was true.
Right. And that if is pretty important.
So one of the first people I called up was Laura Kreidberg.
She studies planetary atmosphere.
She's at the Max Planck Institute for Astronomy in Germany.
I think this is one of those situations where extraordinary claims require extraordinary evidence.
And I'm not sure we're at the extraordinary evidence level yet.
I think we need another look to get all the way there.
Well, let's start at the basics.
Do you believe that they have detected these molecules in these quantities?
Not really. If I'm being straight with you, not really.
Wow. I think that we are in the very early stages of learning how to interpret the data from the James Webb Space Telescope.
It's a tricky business.
These are really, really small signals.
We've just been at it for a couple of years.
She says that this kind of measurement is just incredibly, incredibly hard. And, you know, she wasn't the only skeptic.
Another astronomer told me he really wouldn't be surprised if the signal just disappeared when people did independent analysis of the data.
Oh wow. And then Ryan Macdonald, that astronomer from the university of Michigan quickly wrote up this little critique of the research paper and he posted it on the blue sky social media site and it gets into super nitty -gritty statistics but the signal is just not strong enough to say there's anything there in the atmosphere with these observations.
So that's a few critics but like how did this land overall?
From what I can tell there's a general consensus that the strength of the evidence did not warrant the kind of enthusiasm that surrounded it and you know already there's been more than one reanalysis of the data put out there.
The first one I saw was from Jake Taylor at the University of Oxford. His study sort of said there's too much noise in the data to reliably find any kind of signal of these gases or anything else for that manner.
So what did the original researchers say in response?
Like, obviously, they felt like something was there.
Well, I reached out to a couple of them about Jake Taylor's analysis and Nikhu Madhusudan said the model Jake used was too simplistic and not relevant, but Jake of course disagrees, saying it's a tool that's commonly used to just kind of quickly check telescope observations to see if there's anything worth following up on.
And then there was this other analysis that's just been posted online by another group.
It found that numerous other models that don't have biosignatures at all are also compatible with the observations, so.
It's not looking good right now, I gotta say.
And this is the way science goes.
This is gonna go on and on for months.
Yeah, but you know, the headlines have already been out there about possible signs of life being detected on another planet.
And that really rankles some astronomers like Ryan Macdonald, and for many of us, it's felt like damage control, to be honest, because we we don't want people to think that the ultimate and most important, one of the most important scientific discoveries, potentially this century has kind of already been made, just for it to automatically turn out not to be true.
There's been a lot of hand wringing about this whole episode and how to prevent something like this in the future.
I mean, short of a, like, UFO hovering above Times Square and like aliens coming out of it, the discussion about this stuff is going to be contentious, right?
I mean, like, this is how science is done.
Like, somebody makes a claim, somebody else has to check it to see if it's true or if it can be disproven.
Sure. I mean, it's not like there haven't been similar episodes in the past, like, what about phosphine and the atmosphere of Venus a few years ago?
Do you remember we talked about that one?
Yeah, it was very similar right?
It's another gas associated with life that was detected in a planet's atmosphere, it made headlines, and then people debated whether the detection was even real and if so whether it could have been made by some other process.
Exactly. I mean, Venus has clouds of concentrated sulfuric acid, right?
So Venus is known to be extremely, extremely inhospitable.
And if I recall talking to the researchers then, they were pretty skeptical about the life angle.
Even as they said they couldn't think of any process that could make this gas on Venus, it was more like, we don't really know what's up with Venus, or what could there be besides life that could produce this gas?
This is a mystery that we'd like to solve.
This is kind of bizarre and unexpected.
We don't know what to make of it.
It wasn't like, this is the strongest evidence for life beyond our planet.
Yeah, whatever happened with that, by the way?
My understanding is that the whole thing, like the detection and what it means, like it's still debated.
You need a mission to Venus to settle it, which we could plausibly do, because Venus is close by.
It's literally the planet right next door.
But K2 -18b, not so next door.
Yeah, I mean, we're not going to go visit a planet beyond our solar system anytime soon.
And, you know, here's the thing there's going to be a lot more research in the years ahead trying to tease out information about very, very far away planets.
And I think what this episode is about is scientists talking about how they can do that work and communicate it all to the public.
Like how to convey the excitement of it without overselling it or hyping it.
Because there could only be one time that humans discover life beyond Earth for the very first time.
And to many scientists, that's almost like a sacred thing.
Nell, if that does happen, we expect you to come right here and talk to us about it.
Well, I frankly hope that I'm alive and that NPR is.
Yeah, me too. Thank you so much. Thank you.
This episode was produced by Burleigh McCoy, edited by our showrunner Rebecca Ramirez, and fact -checked by Tyler Jones and Nell.
Maggie Luther was the audio engineer.
Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy.
I'm Regina Barber. Thank you for listening to Shortwave from NPR.
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