Podcast Summary

Podcast: Short Wave (NPR)

Episode: Why Experts Are Racing To Learn About This Interstellar Comet
Date: December 2, 2025
Hosts: Emily Kwong, Regina Barber
Special Guests: Dr. John Tonry (Astronomer, University of Hawaii), Dr. Teddy Kareta (Planetary Astronomer, Villanova University)

Episode Overview

This episode of Short Wave dives into the scientific buzz around Comet 3I/ATLAS, a rare interstellar visitor passing through our solar system. The hosts explore why these visitors fascinate astronomers, what makes 3I/ATLAS unique, and what such comets can teach us about planets orbiting other stars. Along the way, they discuss previous interstellar curiosities, bust common “alien” misconceptions, and share a few cosmic jokes.

Key Discussion Points & Insights

What Makes 3I/ATLAS Special? (02:14–03:14)

• Not from our solar system: 3I/ATLAS is an “interstellar” comet—originating from another star system entirely.
  • “So Em, this comet isn’t from here... She doesn’t even go here.” —Regina Barber (02:05)
• Unlike cyclic comets such as Halley's (which orbits the Sun every 76 years), 3I/ATLAS will only pass by once.
  • “This is just one and done.” —Emily Kwong (02:37)
• Identified as a comet due to its icy nucleus, distinct tail, and a bright cloud of escaping gas and dust seen through telescopes.

Discovery & Significance (03:14–04:11)

• Detected by the NASA-funded ATLAS survey (Asteroid Terrestrial-impact Last Alert System).
  • “It’s the only way we’re ever going to get material from another solar system... certainly within our lifetimes.” —Dr. John Tonry (03:19)
• Third interstellar comet ever recorded (hence, "3I").
• ATLAS scans the sky nightly, primarily looking for objects that could collide with Earth—though 3I/ATLAS poses no danger.

Shooting Down the Alien Hype (04:11–05:04)

• Online rumor mills love to speculate on alien origins, but experts strongly refute this.
  • “I’ll bet you my house at 50/50 odds that it’s natural... I’d be worried about that bet.” —Dr. John Tonry (04:24)
• There’s no scientific evidence supporting extraterrestrial technology.

Why Astronomers Are Obsessed (06:24–07:13)

• Extreme rarity: Interstellar comets are exceedingly uncommon—so much so that astronomers used to doubt they’d ever see more than one in a career.
  • “When the first one of these objects, Oumuamua, was discovered... I really kind of thought, oh, this is the one we’re ever going to find.” —Dr. Teddy Kareta (06:44)
• Even seeing three in a few years marks a huge jump in discovery opportunities.

What Made Oumuamua So Strange? (07:13–10:20)

• First observed interstellar object: 1I/'Oumuamua (2017).
  • Lacked the usual comet tail, moved in slightly odd ways.
  • Sparked speculation about “alien spacecraft” due to atypical acceleration—likely explained by undetectable “volatiles” (ices like nitrogen or hydrogen) outgassing.
  • “There was a little bit, just a teeny weeny bit of extra acceleration... Maybe the most realistic [explanation] are just nitrogen or hydrogen pockets... that got boiled off.” —John Tonry (09:07)
• Consensus: Oumuamua, like 3I/ATLAS, is a natural phenomenon.

Science of Studying Interstellar Comets (10:22–12:47)

• Interstellar comets are believed to carry chemical “clues” about other solar systems—potentially similar to those that formed that star's planets.
  • “So they carry chemical clues from, like, distant worlds.” —Emily Kwong (10:46)
• Composition analyzed by studying the spectrum (color and reflection) of light coming from the comet, revealing ices and gasses.
  • “When you see a comet with your naked eye and notice it looks a smidgen green, that’s because diatomic carbon is glowing in the sunlight....” —Teddy Kareta (11:38)
• Color can change as new gases are exposed with more solar heating; comparing comets helps reveal what’s “normal” across star systems.

Technological Advances in Discovery (12:47–14:29)

• Improved detection doesn’t stem solely from better telescopes—astronomers are also getting better at recognizing fainter, more elusive objects in survey data.
  • “...the teams who do it are getting better at finding fainter kinds of sources in their data.” —Teddy Kareta (13:08)
• Interest is both scientific and practical—plotting orbits protects Earth from potential impacts.

The “Excitement” of Near-Misses (13:33–14:29)

• ATLAS once spotted an asteroid (Y4) that briefly seemed on course for a major (if non-lethal) Earth impact in 2032—since ruled out, to the disappointment of Tonry.
  • “Oh, it could have been so good. It was so perfect... It would have been a big explosion. But we would have been fine. People would have been fine.” —John Tonry (13:40)
  • “Why is it a disappointment? Did you want to be like the one? To be like, I found it. We can make preparations?” —Regina Barber (14:03)
  • “Yes.” —John Tonry (14:08)

Wrap-up (14:29–14:41)

• Comets like 3I/ATLAS aren’t aliens—but their study brings us closer to understanding other planetary systems and keeps astronomers (and astrophysicists) very excited.
  • “This is our beat now. Interstellar. Interstellar forever.” —Regina Barber (14:38)

Notable Quotes & Memorable Moments

• “This comet isn’t from here. Like, she doesn’t even go here.” —Regina Barber, referencing “Mean Girls” (02:05)
• “So it'd be like invisible comet farts.” —Emily Kwong, on undetectable gas expulsion (09:39)
• “There was a little bit, just a teeny weeny weeny bit of extra acceleration. And that was ascertained as it was moving away. And people got very excited about that.” —John Tonry (09:07)
• “I’ll bet you my house at 50/50 odds that it’s natural and I'll take you to the bank every day.” —John Tonry, on the alien-tech rumors (04:24)
• “When you see a comet with your naked eye and you notice it looks a smidgen green, that’s because diatomic carbon...is glowing in the sunlight.” —Teddy Kareta (11:38)
• “This is our beat now. Interstellar. Interstellar forever.” —Regina Barber (14:38)

Timestamps for Key Segments

• [02:14] – What is 3I/ATLAS and why is it unique?
• [03:19] – John Tonry on why interstellar comets matter.
• [04:11] – The alien technology rumor (debunked).
• [06:44] – Teddy Kareta on seeing his first interstellar comet.
• [07:30] – Why Oumuamua was so puzzling.
• [09:07] – Unusual movement and “invisible comet farts.”
• [11:38] – Analyzing comet colors and composition.
• [13:08] – Advances in discovering interstellar comets.
• [13:40] – Near-miss asteroid and John Tonry’s “disappointment.”
• [14:38] – Interstellar comets are here for science, not aliens.

Summary Takeaways

• 3I/ATLAS is a once-in-a-lifetime interstellar comet offering scientists rare insights into planetary systems beyond ours.
• Despite internet speculation, expert consensus is that interstellar comets are natural, not artificial or alien technology.
• Studying their composition helps astronomers test if our solar system is chemically typical or unique in the galaxy.
• Recent technological and methodological advances have made these discoveries possible and more frequent.
• The excitement over these comets blends deep scientific curiosity with a healthy dose of cosmic humor.