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)

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.

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.”

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).

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.”

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.”

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

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.

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.