Hot galaxies alert!

Summary

Short Wave Podcast Summary

Episode: Hot galaxies alert!
Date: January 9, 2026
Hosts: Emily Kwong, Burleigh McCoy, with guest Scott Detrow (from NPR's All Things Considered)
Duration: ~9 Minutes (content only)

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Overview

This lively and informative episode of NPR’s Short Wave dives into three major recent discoveries in science: the detection of an unexpectedly "hot" galaxy cluster in the early universe, the extraordinary smelling abilities of elephants and how these help them forage for food, and a surprising genetic twist in the migration of painted lady butterflies. With humor and clarity, hosts Emily Kwong and Burleigh McCoy—and guest Scott Detrow—break down the complexity of cosmic evolution, animal behavior, and genetics for a broad audience.

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Key Discussion Points & Insights

1. A Hot Galaxy Cluster in the Early Universe

[02:04–03:50]

• What’s the news?
  Scientists have discovered a galaxy cluster from about 12 billion years ago, making it surprisingly young in the universe’s 13.8-billion-year timeline—yet this cluster is much hotter than theories would predict.

• Why is this surprising?

  • Cosmic models suggest young galaxy clusters should be relatively cool.
  • This cluster's temperature is "hotter than the surface of the sun."
  • Contains multiple active galaxies—three have supermassive black holes at their centers, which is unusual for such an early stage.

• Expert take:
  Astrophysicist Jorge Moreno (not involved in the study) compares it to “going back a few centuries and seeing a modern metropolis instead of simple buildings and horse-drawn carriages."

  • Quote [03:09, paraphrased]:
    “If you go back a few centuries, you expect to see little buildings and horse carriages, not a modern metropolis.”

• Implications:
  This discovery challenges existing ideas of how large structures, like galaxy clusters, form and evolve—suggesting that scientists will need "more data" to know if this is a cosmic outlier or a new normal.

• Memorable exchange:

  • Scott Detrow, [02:37]:
    “So that’s just a fast billion years, like a snap of the fingers in galaxy terms…”
  • Emily Kwong, [02:45]:
    “Exactly. And current theories say that younger galaxy clusters should be relatively cool, but this one is very hot, like hotter than the surface of the Sun.”

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2. Elephants’ Extraordinary Sense of Smell

[04:05–06:19]

• What’s the news?
  New research shows elephants use their trunks, equipped with nearly 2,000 olfactory genes (far more than humans or even dogs), to detect and choose the largest available sources of food—even without seeing them.

• How was it tested?

  • Scientists built a large Y-shaped maze, hiding two piles of food at the end of each arm.
  • Elephants could not see the food, but—when the difference was significant—they could smell and consistently pick the larger food pile.

• Findings:
  Elephants nearly always picked the larger amount as long as the difference was at least 600 grams (roughly 6-10 trunkfuls of grass).

• Quotes & moments:

  • Burleigh McCoy, [04:26]:
    “If you do [hire an elephant to sniff], pay them fairly in what they love, grass leaves.”
  • Scott Detrow, [05:10] (joking):
    “So it's like, choosing almost between, like, two different Las Vegas buffets, not being able to see which one was bigger.”

• Significance:
  Understanding how elephants use smell may help limit their environmental impact (e.g., by masking crops or endangered plants with bad odors).

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3. Painted Lady Butterflies & the Genetics of Migration

[06:19–08:45]

• What’s the news?
  The painted lady butterfly—the most migratory butterfly species—has opposite migration pathways depending on its hemisphere, due to the equator acting as a "migration barrier."

• Discovery details:

  • Scientists sampled over 300 butterflies from 38 countries.
  • A dramatic DNA flip:
    In southern hemisphere butterflies, a chunk of DNA related to migration is reversed relative to their northern counterparts.

• Why does it matter?
  This is the first described case of a migration barrier in any insect, offering an evolutionary “lens" into how single species could split into two—potentially explaining how closely related species in different hemispheres diverge due to migration obstacles.

• Quotes & moments:

  • Emily Kwong, [07:28]:
    “We talked to Aurora Garcia Berro...and she says their team looked at the butterflies' genes for months. ... and then one day, she found something really weird.”
  • Aurora Garcia Berro (as relayed by Emily), [07:30]:
    "I actually thought it was an artifact, but then I showed it to my colleague, and they were like, completely surprised. Like, you don't know."
  • Scott Detrow, [07:54]:
    “Whoa.”

• Broader significance:
  Painted lady butterflies can influence ecosystems and agriculture—at times blocking weather radar with their migration swarms.

  • Burleigh McCoy, [08:21]:
    "Identifying how animals migrate is important to understanding the health of that species... but also the health of all the places that species travels.”

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Notable Quotes & Memorable Moments

• A city from the 1700s looking like Las Vegas:

  • Burleigh McCoy, [03:13]:
    “This galaxy cluster is poppin’. It's far hotter than scientists expected to find at this early point in the universe.”
  • Scott Detrow, [03:12]:
    “Like it's late 1700s and a city…looks like Las Vegas.”

• Elephants & food:

  • Scott Detrow, [05:10]:
    “So it's like, choosing almost between, like, two different Las Vegas buffets…”
  • Emily Kwong, [04:12]:
    “At the very tip of an elephant trunk are two nostrils powered by nearly 2,000 olfactory genes, which is five times more than a human has and over twice as many as dogs.”

• On unexpected science:

  • Scott Detrow, [08:45]:
    “That is so interesting. I started off thinking like, oh yeah, everybody knows that. To like having my mind kind of blown. That was a really interesting story.”
  • Emily Kwong, [08:51]:
    “That's why you come here.”

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Timestamps for Key Segments

• [02:04] – Galaxy cluster discovery introduction
• [02:37] – Context: Age and temperature surprise
• [03:42] – Supermassive black holes in the young cluster
• [04:05] – Elephant sense of smell and foraging behaviors
• [05:16] – Elephant Y-maze experiment details
• [06:19] – Painted lady butterfly migration and genetics
• [07:39] – Discovery of the flipped DNA segment
• [08:21] – Importance of migration in ecological health

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Tone & Approach

The episode is fast-paced, curious, and playful, blending scientific accuracy with humor. Scott Detrow’s wry enthusiasm, combined with Burleigh and Emily’s accessible explanations, make complex topics inviting and relatable, often using analogies (“Las Vegas buffet,” “city in the 1700s”) to demystify cosmic and biological phenomena.

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Conclusion

“Hot galaxies alert!” delivers bite-sized, remarkable science—from cosmic puzzles to animal superpowers—in a style that’s as entertaining as it is educational, all within a 15-minute package. Whether you’re a space buff, animal lover, or curiosity-driven learner, this episode offers something truly mind-bending.

Transcript

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[Burleigh McCoy]

You're listening to shortwave from NPR.

[Emily Kwong]

Hey, shortwavers.

[Burleigh McCoy]

Burleigh McCoy here and Emily Kwong with.

[Emily Kwong]

Our bi weekly science news roundup featuring the hosts of All Things Considered. And today we have have Scott Detrow.

[Scott Detrow]

I'm only here because I heard we were talking about a hot galaxy cluster.

[Burleigh McCoy]

That's how we get you in the door. Yeah, but how we're gonna keep you.

[Emily Kwong]

Is talking about also how elephants trunks lead them to food.

[Burleigh McCoy]

And we'll share a big discovery in butterfly migration.

[Scott Detrow]

I'm here for all three.

[Burleigh McCoy]

Well, we thank you all that on this episode of Short Wave, the science podcast from n.

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[Burleigh McCoy]

Okay, Scott, I know your favorite thing is space. So let's start there.

[Scott Detrow]

Let's start there.

[Burleigh McCoy]

Wow.

[Scott Detrow]

Let's start off. What would you say a galaxy cluster is, though? Let's start there.

[Burleigh McCoy]

It is exactly what it sounds like. It is a collection of galaxies, but kind of like a city where each galaxy is a different building. Our galaxy, the Milky Way, is part of a cluster called the Local Group, for example. But the galaxy cluster we want to talk about, which is the subject of a new paper in Nature, was formed about 12 billion years ago and the universe itself is only about 13.8 billion years old.

[Scott Detrow]

So that's just. That's just a fast billion years, like a snap of the fingers in galaxy terms, like we're talking about this. This was a baby in galactic years.

[Emily Kwong]

Exactly. And current theories say that younger galaxy clusters should be relatively cool, but this one is very hot, like, hotter than the surface of the Sun. We talked to Jorge Moreno, an astrophysicist who didn't work on the paper, and he made an analogy to US History. He said, if you go back a few centuries, you expect to see little buildings and horses and carriages, not a modern metropolis.

[Burleigh McCoy]

Like it's late 1700s and a city.

[Scott Detrow]

Looks like Las Vegas.

[Burleigh McCoy]

This galaxy cluster is poppin. It's far hotter than scientists expected to find at this early point in the universe.

[Scott Detrow]

Do researchers have any idea why it's so hot?

[Burleigh McCoy]

We don't know why yet, but one of the study authors, Daji Zhou, says it is the first time a galaxy cluster this hot has been detected at such a young.

[Emily Kwong]

And this cluster also contains active galaxies. Three of them have supermassive black holes at the center, which is also surprising, given the cluster's age.

[Burleigh McCoy]

So this forces us to rethink our current understanding of how these large structures.

[Scott Detrow]

Form and evolve in the universe.

[Burleigh McCoy]

Although, Scott, it is possible that this cluster is an extreme case. So we need more data.

[Scott Detrow]

I have a lot of other questions that I will keep googling, but for now, we are going to move forward to another topic, though, because we got a lot to talk about, and we got to talk about elephants.

[Burleigh McCoy]

That was really good.

[Scott Detrow]

Thank you, listeners. Don't see that I flared my hand like a trunk. But the trunks are what we're talking about, right?

[Emily Kwong]

Yes, big time. At the very tip of an elephant trunk are two nostrils powered by nearly 2,000 olfactory genes, which is five times more than a human has and over twice as many as dogs.

[Scott Detrow]

Which makes me think, if you need to sniff something out, hire an elephant, not a dog.

[Burleigh McCoy]

Yeah. And if you do, pay them fairly in what they love, grass leaves. Because elephants eat hundreds of pounds of plants a day, they are constantly making food decisions about whether to stay foraging in a patch or travel in search of a better one. And Adrian Schrader at the University of Pretoria wanted to know how their noses guide them in the wild.

[Scott Detrow]

Animals don't just randomly walk across the landscape and hope to find food. And so our question really was an idea of, well, do they use the amount of food as a cube?

[Emily Kwong]

Yeah. And to test this, Adrian's team built a giant maze for elephants, shaped like a Y, with walls over seven feet tall. So picture one entrance, two paths with different quantities of food at either end.

[Scott Detrow]

So it's like, choosing almost between, like, two different Las Vegas buffets, not being able to see which one was bigger.

[Burleigh McCoy]

Exactly. Four captive elephants took on this challenge. From the maze entrance. The food was 30ft away, so way beyond the reach of their trunks. They couldn't see because the walls were so tall. And every time, they chose the path with more food, unless the quantity difference was less than 600 grams, which is about 6 to 10 trunk loads of grass. And then they tended to pick either route, which suggests they couldn't smell the difference, or they just didn't care. These results were published in the journal Biology Letters.

[Emily Kwong]

And Alvaro Lopez Kea, who was not part of the study, found the elephants ability to discriminate food quantities. Remarkable. Though he points, there are a lot more smells in the wild than in the preserve where these captive elephants lived.

[Scott Detrow]

This is really interesting. I'm curious, like, what is useful about this research?

[Burleigh McCoy]

Well, elephants, while adorable, can damage their environments. They stomp on farmers, crops. They can knock down endangered trees. But if researchers understand elephants use of smell, maybe they can cover plants with bad odors to protect them from hungry elephants.

[Scott Detrow]

All right, so let's go from a very large animal to a very small one. Let's talk butterflies, specifically butterfly migration. What's surprising about it?

[Sponsor/Advertisement Voice]

Yeah.

[Emily Kwong]

So this is a migration in painted lady butterflies. They have similar coloring to monarchs, but they're smaller, they're super widespread, and they have the longest migration of any butterfly. And scientists found something striking in that migration that depending on if they live in the northern or southern hemisphere, they follow completely opposite migration paths. Essentially, the equator is acting as a migration barrier for these two isolated populations.

[Scott Detrow]

Okay, I'm gonna. I'm gonna be honest here. This doesn't particularly surprise me. Right. The seasons are opposite. This makes sense. Why is it a big deal?

[Burleigh McCoy]

Fair. But this is the first time a migration barrier has been described for any insect. And to study this, researchers collected more than 300 butterflies from 38 countries across the northern and southern hemispheres.

[Emily Kwong]

We talked to Aurora Garcia Berro from the Botanical Institute of Barcelona, and she says their team looked at the butterflies genes for months, searching for clues about what made these two populations dist. And then one day, she found something really weird. And I actually thought it was an.

[Burleigh McCoy]

Artifact, but then I showed it to.

[Emily Kwong]

My colleague, and they were, like, completely surprised. Like, you don't know.

[Burleigh McCoy]

This is so exciting and this dramatic.

[Scott Detrow]

What was it?

[Burleigh McCoy]

Yeah, they found that a large chunk of DNA in the Southern hemisphere butterflies was completely flipped. It was oriented the other way than the same DNA chunk in the Northern Hemisphere butterflies. And this chunk contains genes involved in migration.

[Scott Detrow]

Whoa.

[Emily Kwong]

So what they think they're seeing is one species that separated into two populations. And now their genetics are diverging too because of these different migration pathways. And this is sort of a lens into how a single species might split into two across a migration barrier. And it might explain why we see closely related species in different hemispheres. They published the results in the journal Nature Communications.

[Scott Detrow]

That is really interesting. What is the thinking on the larger significance of this?

[Burleigh McCoy]

Well, painted lady butterflies, while small, make up a huge biomass. In 2017, a 70 mile stretch of these butterflies blocked weather radar in Colorado. They can affect agriculture, pollination, and the health of other species. So Aurora says identifying how animals migrate is important to understanding the health of that species. Yes, but also the health of all the places that species travels.

[Scott Detrow]

That is so interesting. I started off thinking like, oh yeah, everybody knows that. To like having my mind kind of blown. That was a really interesting story.

[Burleigh McCoy]

Great.

[Emily Kwong]

That's why you come here. Thank you, Scott.

[Scott Detrow]

Thank you.

[Emily Kwong]

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

[Burleigh McCoy]

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

[Emily Kwong]

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

[Burleigh McCoy]

Tyler Jones checked the facts. Robert Rodriguez and Jay Sz were the audio engineers. I'm Emily Kwong.

[Emily Kwong]

And I'm Burleigh McCoy. Thanks for listening to Short Wave, the science podcast from npr.

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