Could This Exoplanet Harbor Life?

Summary

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Podcast Summary: Could This Exoplanet Harbor Life?

Podcast: Short Wave (NPR)
Hosts: Emily Kwong, Regina Barber
Guest Host: Elsa Chang
Date: December 12, 2025
Episode Run Time: ~15 minutes

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Episode Overview

This bi-weekly science news round-up dives into three intriguing topics: the search for life on an Earth-sized exoplanet (Trappist-1e), a new climate-centric theory behind the Black Death, and a grisly dive into how ants protect their colonies from disease. As always, the show balances deep scientific insight with wit, energy, and accessible explanations.

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Key Topics & Insights

1. Exoplanets and the Search for Life

Starts at 04:11

• Exoplanets Primer:
  Regina kicks off with, “Astronomers have already discovered more than 6,000 exoplanets… some of them are more promising spots to look for life than others, like this exoplanet called Trappist-1e.” (04:18)

• What Makes Trappist-1e Special:

  • It’s rocky, Earth-sized, and “smack dab in the habitable zone” of its star, also called the Goldilocks Zone, meaning it receives just the right amount of light for possible liquid water (04:18).
  • Guest scientist Sukrit Ranjan elaborates:

    "It’s at this really interesting distance from its host star. It gets a little bit less light than Earth does, but way more than Mars does. If there’s life on it, we have the best chances of detecting it if it’s present on Trappist-1e." (04:42)

• Ingredients for Habitability:

  • The hosts recap the main requirements: not too hot, not too cold, plus the presence of an atmosphere (05:19).
  • Ranjan emphasizes:

    "It turns out to be really hard if it has an atmosphere, for it not to be habitable." (05:32)

• How Scientists Investigate:

  • Planets are analyzed as they pass in front of their star; the starlight passing through their atmosphere can be analyzed for biosignature molecules like CO₂ or methane (05:59).

• Study Results & Setbacks:

  • Emily summarizes:

    "Drumroll… sadly, no. A more in-depth investigation of Trappist-1e revealed no CO₂ and found that there may be no methane either. Oh, and… the majority of these Titan-like exoplanets, called exotitans, most likely lack an atmosphere entirely." (06:24)

  • Ranjan’s verdict:

    “The answer we came out to was, man, Exo Titans. Great idea. Not looking super good.” (06:44)

• Takeaway:

  • Elsa asks, “So is he saying habitable planets might actually be rarer than scientists previously thought?” (06:50)
  • Regina clarifies, “At least these kinds of habitable exoplanets… we really just need, like, better telescopes to get to the bottom of this.” (06:56)

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2. Was the Black Death Triggered by Volcanoes?

Starts at 07:03

• Historical Context:

  • Emily sets the scene: “One of the most defining events of that time, the Black Death, which killed one third to one half of the population of Europe.” (07:10)
  • Elsa: “It was rats, wasn’t it? That’s what I always thought.” (07:24)
  • Regina corrects: “Close, Elsa. It was a bacterium… spread by fleas on rodents that hitched a ride from the shores of the Black Sea to what is now Italy in 1347.” (07:25)

• A New Climate Link:

  • Emily introduces new research:
    • Scholar Hannah Barker discovered a grain trade reopening in 1347, possibly explaining the rodent influx.
    • Regina: “This raised a question – why were Italian states worried about famine that year? Martin Bauch… thinks it might have to do with volcanoes that erupted a few years prior.” (07:58)
  • Bauch’s hypothesis: “There must have been a major volcanic eruption when sulfate is put into the higher strata of the atmosphere… then circling the globe for up to three years.” (08:11)

• Evidence:

  • Tree ring samples showed bad growth conditions pre-plague; ice cores showed high sulfate aerosols, both pointing to a volcanic event around 1341 (08:46).

• Summing It Up:

  • Elsa encapsulates:

    “Volcanic activity led to some sort of climate downturn, which led to crop failure, which led to grain imports coming in that brought all these rats carrying the bacteria to Italy. And then a bunch of people died.” (09:06)

  • Emily adds, “Now, this is just a hypothesis, of course, but it suggests that one of the biggest pandemics in human history could have been connected to the climate.” (09:23)

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3. Sick Ants Call for Their Own Destruction

Starts at 09:32

• Discovery:

  • Regina introduces the “gory tale, but for the common good” — ants using chemical signals to ask nestmates to kill them if they’re infected, preventing colony-wide outbreaks (09:43).

• Mechanism:

  • Worker ants pay close attention to juvenile ants (pupae) in cocoons. Infected pupae emit a chemical signal.
  • Emily cites researcher Erica Dawson:

    “First the worker ants peel off the cocoon and then they bite holes in the pupae and then they spray formic acid. And this basically serves to disinfect the infected pupae because it kills off the fungus.” (10:11)

• Self-Sacrifice in Nature:

  • Regina: “While the acid kills off the fungus, it also kills the pupae. So in effect, the pupae is essentially calling for its own death, saying hey, I’m sick.” (10:49)
  • Elsa: “Kill me now before I get you sick too.” (10:59)
  • Emily: “Yes, that is the dramatic monologue of these infected ants, though there is a plot twist…” (11:02)
    • Queen pupae do not send the signal even when sick, and are more likely to survive infection on their own.
    • Regina: “Future queens just… they don’t signal when they’re sick.” (11:23)
    • Elsa: “They’re above the self-sacrifice.” (11:25)
    • Emily: “Yes they are. And also the infected future queens could fight off the infection on their own.” (11:25)

• Memorable exchange:

  • Elsa jokes: “True queen. Just like Emily Kwong and Regina Barber from NPR science podcast Short Wave.” (11:30)
  • Regina: “Elsa, thank you so much for coming to talk with us about science and calling us queens because we are news queens.” (11:38)

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Notable Quotes & Memorable Moments

• “If there’s life on it, we have the best chances of detecting it if it’s present on Trappist-1e.” — Sukrit Ranjan, 04:42
• “Drumroll… sadly, no. A more in-depth investigation of Trappist-1e revealed no CO₂ and found that there may be no methane either.” — Emily Kwong, 06:24
• “Exo Titans. Great idea. Not looking super good.” — Sukrit Ranjan, 06:44
• “Volcanic activity led to some sort of climate downturn, which led to crop failure, which led to grain imports… and then a bunch of people died.” — Elsa Chang, 09:06
• “While the acid kills off the fungus, it also kills the pupae. So in effect, the pupae is essentially calling for its own death, saying hey, I’m sick.” — Regina Barber, 10:49
• “True queen. Just like Emily Kwong and Regina Barber...” — Elsa Chang, 11:30

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Timestamps for Important Segments

• 04:11 – Segment begins: Trappist-1e, habitability, and atmospheric findings
• 06:44 – Ranjan’s verdict on exo Titans and planetary rarity
• 07:03 – Black Death and the climate connection
• 08:46 – Scientific evidence for historic volcanic activity
• 09:32 – Ants' self-sacrifice chemical signaling
• 10:49 – The biology and ethics of ant colony behavior
• 11:25 – The exceptional case of queen ants’ immunity

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Tone and Style

Light, witty, and inviting — the hosts cultivate both scientific curiosity and friendly banter (“True queen. Just like Emily Kwong and Regina Barber…”). There’s a clear drive to demystify complex research for all listeners, with clarifying analogies and playful asides keeping things accessible and fun.

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In short:
This episode offers a whirlwind tour through the latest astrobiology, history, and animal behavior research. Listeners walk away with fascinating new questions and memorable scientific tidbits in under fifteen minutes — in classic, irreverent Short Wave style.

Transcript

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[Emily Kwong]

Hey, short wavers. Emily Kwong here. Real quick. Before the show, let's talk about public media. Public media has been in the news a lot this year, and public media is what makes NPR shows like Shortwave special it's made for you. When you listen to an NPR podcast, the people who make it aren't thinking about shareholders or advertisers. We're thinking about you and delivering on a promise to help you understand the world a little better. From its very founding in the US Public media was also meant to tell stories from underrepresented communities, providing cultural insight that expands your perspective. At npr, we still believe in all of that. We, we always will. But as of this fall, federal funding for public media, including NPR and local NPR stations, has been eliminated. And now we're heading into an uncharted future. But we know you won't let public media go away. We rely on your support to bring you shortwave now more than ever. This year, we have loved bringing you stories about, among many other things, what happens inside a top secret nuclear facility, whether kids should be taking melatonin, why flowers are blooming early, how how nightmares work, and what happens when AI cannibalizes its own data. And we cannot wait to bring you more episodes like that in 2026. So thank you if you already go the extra mile as an NPR supporter. If not, you can join THE PLUS community now. There has never been a better time. You get a bunch of perks like bonus episodes and more from across NPR's podcasts. Support Public media by signing up for NPR [e-mail] Thank you so much. You're listening to Shortwave from NPR.

[Regina Barber]

Hey, Shortwavers, Regina Barber here and Emily Kwong with our bi weekly science news roundup featuring the hosts of All Things Considered. And today we have the legendary Elsa Chang from la.

[Elsa Chang]

Thank you for having me yet again. So what are we learning about today?

[Regina Barber]

So, Elsa, we're giving you an update on the chances of life on an Earth sized planet that orbits another star.

[Emily Kwong]

We'll complicate the saga of the Black Death with a story of how it may have been driven by volcanoes.

[Sponsor/Ad Voice]

What?

[Regina Barber]

And why sick ants let nestmates destroy them.

[Emily Kwong]

Ugh, dark.

[Regina Barber]

Okay, all of that on this episode of Shortwave, the science podcast from npr.

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[Emily Kwong]

All right, Elsa, where do you want to start?

[Elsa Chang]

Let's start with the Earth sized planet around another star. Gina, go.

[Regina Barber]

Okay, so astronomers have already discovered more than 6,000 exoplanets, and those are planets that are orbiting stars, not our sun. And some of them are more promising spots to look for life than others, like this exoplanet called Trappist 1e. And this planet is rocky like Earth. It's the same size. It's orbiting at a distance that smack dab in the habitable zone of the star, sometimes called the Goldilocks Zone.

[Sukrit Ranjan]

Yes, it's at this really interesting distance from its host star. It gets a little bit less light than Earth does, but way more than Mars does if there's life on it. We have the best chances of detecting it if it's present on Trappist1e.

[Emily Kwong]

That's Sukrit Ranjan, the lead author of a recent study about Trappist1e, published in the journal Astrophysical Journal Letters. Now, what Sukrit is saying is that we have the best chances of finding life there in the Goldilocks zone, as opposed to some of these other exoplanet systems.

[Elsa Chang]

This is so fascinating. Wait, just remind me, what are like the ingredients that scientists look for when deciding whether there can be life on a planet?

[Emily Kwong]

Well, the reason this zone is important is because it's not too hot, such that water evaporates off the surface and not too cold, such that the planet would be covered in ice. Another key ingredient for life on a Planet is having an atmosphere.

[Sukrit Ranjan]

It turns out to be really hard if it has an atmosphere, for it not to be habitable.

[Regina Barber]

That atmosphere allows liquid water to stick around, which is definitely good for life. But, Elsa, there are other places in our solar system that scientists are looking at for possible life that also have atmospheres, like Earth, places like Saturn's moon, Titan. So this study looked at Trappist1e and the potential existence of Titan, like X exoplanets.

[Sponsor/Ad Voice]

Wow.

[Elsa Chang]

Okay, so how did they go about doing that?

[Regina Barber]

So when Trappist1e orbits its star, it occasionally passes between the star and us, viewing it, sort of eclipsing the star. So when that happens, the starlight goes through the exoplanet's atmosphere, if it has one. And studying that light can show if the atmosphere has certain molecules like CO2 or methane.

[Emily Kwong]

And CO2 and methane could be, but don't have to be, signs of life.

[Elsa Chang]

Oh, so wait, does this exoplanet have CO2 and methane?

[Sponsor/Ad Voice]

I hope.

[Emily Kwong]

Drumroll sadly, no. A more in depth investigation of Trappist1e revealed no CO2 and found that there may be no methane either. Oh, oh, and by the way, the study also noted that the majority of these Titan, like exoplanets called exotitans, most likely lack an atmosphere entirely.

[Sukrit Ranjan]

The answer we came out to was man, Exo Titans. Great idea. Not looking super good.

[Elsa Chang]

Okay, so is he saying habitable planets might actually be rarer than scientists previously thought?

[Regina Barber]

Well, at least these kinds of habitable exoplanets. And these scientists said that we really just need, like, better telescopes to get to the bottom of this.

[Elsa Chang]

All right, okay. Well, this next study is a bit closer to home, planet Earth. But we're going to time travel for this one, right?

[Emily Kwong]

To the Middle Ages. Yeah. Yes. And to one of the most defining events of that time, the Black Death, which killed one third to one half of the population of Europe. And we have a pretty good understanding of what caused the Black Death.

[Elsa Chang]

It was rats, wasn't it? That's what I always thought.

[Regina Barber]

Close, Elsa. It was a bacterium from Central Asia spread by fleas on rodents that hitched a ride from the shores of the Black Sea to what is now Italy in 1347.

[Emily Kwong]

And the reason, Elsa, that scholars think so many rats were hitching a ride to Italy that year had to do with food. Hannah Barker, a historian at Arizona State University, discovered there was a reopening of the grain trade between the Mongol Empire and Genoa in 1347. They thought they were doing a good thing bringing food to hungry realized that they were also carrying bacteria.

[Regina Barber]

And this raised a question, like why were Italian states worried about famine that year? Martin Bauch, a historian in Germany, has a really cool hypothesis. He thinks it might have to do with volcanoes that erupted a few years prior.

[Emily Kwong]

There must have been a major volcanic.

[Regina Barber]

Eruption when sulfate is put into the higher strata of the atmosphere, up to the stratosphere, then circling the globe for.

[Emily Kwong]

Up to three years, and then at some point coming down.

[Regina Barber]

His team hypothesized that volcanic activity in 1341 led to extreme rainfall. It also led to widespread flooding and ultimately crop failure throughout Europe.

[Elsa Chang]

This is quite a story. Okay, so what evidence do they have? Like, how do you prove volcanic activity from seven centuries ago?

[Emily Kwong]

Totally. It's really interesting. So Martin and his colleague Ulf Buntgen looked at ancient tree ring samples which found bad growth conditions in the years leading up to the plague. They looked at ice cores containing unusually high deposits of sulfate aerosols, which suggests volcano. And they published their findings in the journal Communications Earth and Environment.

[Elsa Chang]

This is amazing. Okay, let me just make sure I understand this. Volcanic activity led to some sort of climate downturn, which led to crop failure, which led to grain imports coming in that brought all these rats carrying the bacteria to Italy. And then a bunch of people died.

[Emily Kwong]

Yep, beautifully summarized. Now, this is just a hypothesis, of course, but it suggests that one of the biggest pandemics in human history could have been connected to the climate.

[Elsa Chang]

That is so interesting. Okay, moving on to our very last topic. Sick ants calling for their own extermination.

[Emily Kwong]

What?

[Regina Barber]

Yeah, it's a.

[Emily Kwong]

That's sick.

[Regina Barber]

Yeah, yeah, it's a gory tale, but for the common good. Okay, so a recent study in the journal Nature Communications found that sick ants send chemical messages to their nest mates, signaling that they're sick. Then worker ants pick up those signals, destroy the sick ants before they infect the others, because, you know, like a fungal infection could take out the whole colony.

[Elsa Chang]

Wait, so these ants are like self sacrificing?

[Emily Kwong]

Yeah.

[Elsa Chang]

That is dark. Okay, how does this happen exactly?

[Emily Kwong]

Yeah. Okay, so it turns out worker ants are paying close attention to the pupae. That's the stage when juvenile ants are still in their little cocoons. And it appears that when pupae have an infection, like a fungus, they send out a chemical message calling for those worker ants to destroy them. One of the study authors, Erica Dawson, explained the process to us. She says first the worker ants peel off the cocoon and then they bite holes in the pupae and then they spray and formic acid. And this basically serves to disinfect the infected pupae because it kills off the fungus.

[Regina Barber]

And while the acid kills off the fungus, it also kills the pupae. So in effect, the pupae is essentially calling for its own death, saying hey, I'm sick.

[Elsa Chang]

Kill me now before I get you sick too.

[Emily Kwong]

Yes, that is the dramatic monologue of these infected ants, though there is a plot twist. The team looked at pupae that would eventually become queens, like ants that start their own colonies, and they found out two things. First, that these queen pupae didn't release the signal even when they were infected. Future queens just they don't signal when they're sick.

[Elsa Chang]

They're above the self sacrifice.

[Emily Kwong]

Yes they are. And also the infected future queens could fight off the infection on their own.

[Regina Barber]

Bam.

[Elsa Chang]

True queen. Just like Emily Kwong and Regina Barber from NPR science podcast Short Wave.

[Regina Barber]

Thanks Elsa. Elsa, thank you so much for coming to talk with us about science and calling us queens because we are news queens.

[Elsa Chang]

You guys are queens.

[Emily Kwong]

Podcast Queen recognizes News Queens.

[Elsa Chang]

Your highnesses, it has been an honor to join you.

[Regina Barber]

You are always welcome in our realm.

[Emily Kwong]

Deeply vows y.

[Regina Barber]

You can hear more of Elsa on consider this NPR's afternoon podcast about what the news means for you.

[Emily Kwong]

And for more science stories just like this one, follow shortwave on whatever app you're listening to.

[Regina Barber]

This episode was produced by Rachel Carlson and Jordan Marie Smith. It was edited by Rebecca Ramirez and Christopher and Taliata.

[Emily Kwong]

Tyler Jones checked the facts. Maggie Luthar was the audio engineer. I'm Emily Kwong.

[Regina Barber]

And I'm Regina Barber. Thank you for listening to Shorewave, the science podcast from npr.

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