Why Astronomers Are Excited About Comet 3I/ATLAS’ Close Approach

Comet 3I/Atlas is just the third known object to visit us from outside our solar system. So yes... we'll be talking about aliens.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:02Flora Lichtman?

  Hey, I'm Flora Lixman, and you're listening to Science Friday. Today in the show, an attention-hogging, larger-than-life celebrity that everyone, and I mean everyone, seems to be talking about: Comet 3I, Atlas. This dirty snowball is a visitor from another solar system, and it's only the third interstellar object we've ever found. And today, today, it's closer to us than ever before, a mere 170 million miles away. So naturally, space nerds like my next guests and me are really excited about this. But 3I has permeated the astrophysicist's bubble and captured the spotlight in a way

• 0:47Flora Lichtman?

  that I think maybe no other big hunk of rock ever has. We will talk about that, too. Here to dish about this interstellar luminary are my guests, Dr. Stephanie Mylum, an astrochemist at NASA who studies comets and interstellar objects, and Dr. Hakim Oluseyi, an astrophysicist who runs the Astronomical Society of the Pacific. Stephanie Hakim, welcome back to Science Friday.

• 1:09Speaker 01

  Thanks for having me.

• 1:11Speaker 02

  Yes, thank you.

• 1:12Flora Lichtman?

  Stephanie, I know interstellar objects are your jam. How pumped are you right now?

• 1:18Speaker 01

  Super excited. This has been a whirlwind of a year since the discovery in July, and we are getting amazing data from telescopes on this object and learning more and more each and every day about its origins, where it's from, and comparing that to objects in our own solar system.

• 1:39Flora Lichtman?

  I want to drill into that in a second, but Hakim, I know you're a space, more of a space generalist. Does it, does this rise to the same level of excitement for you?

• 1:48Speaker 02

  Oh, it definitely does. And, you know, I'm just impressed with the field, right? It just keeps giving, from images of supermassive black holes at the cores of galaxies, to gravitational waves of black holes colliding, to now, you know, interstellar objects coming into the solar system. You know, it just doesn't stop. It's awesome.

• 2:10Flora Lichtman?

  Can't stop, won't stop. Stephanie, what answers are you trying to get while 3I is closest to us?

• 2:15Speaker 01

  We're mostly studying the composition of this object right now. We want to know what it's made of and what clues we can get about where it came from based on that composition. So we're seeing what different molecules are there and what abundances they have, which tells us a little bit about the chemistry of the planetary system that it was formed from. But we're also looking at things like isotope ratios, which are the heavier forms of any given atom, because those are actually from either the primordial Big Bang or are formed in stars of different masses and ages. And that actually tells us about where in the galaxy some of these molecules could have formed

• 3:00Speaker 01

  and how that has then been preserved in this interstellar object.

• 3:04Flora Lichtman?

  Hakeem, what do you want to know about this object?

• 3:07Speaker 02

  Well, you know, what really excites me about these interstellar objects is the fact that we're getting samples of other star systems. You know, when a star forms, it forms as a part of this, you know, more massive structure. It has a star at the core and a disk that will eventually form planets. And in that process, you build up these cometary bodies. You end up with asteroid-like objects. And, you know, every star has a different history. And every cloud that they formed from, you know, they have different chemical abundances. So when a person like Stephanie and her team, they look at the light and figure out what this comet is made of,

• 3:48Speaker 02

  we're getting an understanding of the variations that can exist in these various forming planetary systems.

• 3:55Flora Lichtman?

  The diversity of solar systems, it sounds like.

• 3:58Speaker 02

  Exactly.

• 3:59Flora Lichtman?

  Stephanie, I know we're trying to get James Webb to take a look at this. What can go wrong?

• 4:04Speaker 01

  Um, so, uh, good news. We are looking at it with the James Webb Space Telescope. We got new data just yesterday.

• 4:13Flora Lichtman?

  Yes.

• 4:14Speaker 01

  With one of our instruments onboard. And we're expecting to have more data next week. So hopefully I get a good Christmas present.

• 4:23Speaker 01

  The challenges that we have right now for observing this object with the James Webb Space Telescope is we have to know precisely where in the the sky this object is to point the telescope at the exact position that it's at. This is challenging because it's moving. It's it's flying across our solar system. It just passed the sun, so it's nice and, you know, ramped up in its activity. And that makes it very challenging for us to see where exactly it is in the sky with respect to known stars, so that we can take the James Webb Space Telescope, which is designed to look at the farthest galaxies

• 5:04Speaker 01

  of our universe. So it has this really tiny little window that we can actually peek through. And we have to make that little tiny window fit right on top of this interstellar object. So we've been using telescopes all over the world to try to really hone in on where it is in the sky so that we can make sure we don't miss it with the James Webb Space Telescope.

• 5:25Flora Lichtman?

  This sounds stressful. I'm stressed.

• 5:27Speaker 01

  Yeah, lots. We are, my entire team is on the edge of our seats. We've reached out to all of our colleagues at every telescope, asking them, begging them to get as much data as they possibly can to help us refine this orbit and make sure that we can actually do the observations that we really want to do next week. And can really, you know, put the beacon on this object in the way that we want to.

• 5:55Flora Lichtman?

  We have to talk about aliens because there have been all these alien theories about Three Eye Atlas. I'll ask you both, but in your view, what are the chances that this is an alien craft?

• 6:07Speaker 01

  This looks like a comet. There is no evidence that we've seen to date that there is anything atypical about the composition, the activity, or any other phenomenon.

• 6:22Speaker 01

  So far, nothing has come up as an extreme that can't be explained by our regular physical processes that we see in comets in our own solar system.

• 6:32Speaker 02

  Yeah, there's nothing that says that this is alien. But I'll say this, you know, there are aliens and there are aliens, right?

• 6:40Speaker 01

  Yes.

• 6:41Speaker 02

  So as astrobiologists study the origin of life and where life could possibly be in various niches in the universe, one idea, which is wild and, you know, highly unlikely, but it is still, you know, not completely ridiculous, is that, you know, comets could possibly hold microscopic life forms, right? We've already found a lot of complex biological molecules on comets. So, you know, if you're talking about microbial life, hey, there's a tiny probability that there might be something like that. But if you're talking about the Klingons or the Ferengi or, you know, an alien civilization, I think the probability is vanishingly small.

• 7:23Speaker 01

  Hakim, is there any teeny tiny little part of you that feels disappointed?

• 7:28Speaker 02

  No.

• 7:29Speaker 01

  Not even the smallest corner of your heart?

• 7:33Speaker 02

  Well, so to be disappointed, the expectation has to be there, right? And I never had the expectation in terms of an alien craft, because, you know, there are a lot of assumptions that go into that. Anytime you see an alien depicted in fiction, you know, and they're kind of human-like, that means that they were a primate that evolved in a canopy of trees somewhere, right? What's the probability of that? That's not, you know, it's not happening. It just seems, you know, that is what humans would do. And my general smell test for anything that is said to be alien is how similar is it to humans? And if it's similar in any way, then it's projection. You're not letting the data tell you the story.

• 8:18Speaker 02

  You're projecting your hopes and dreams onto it.

• 8:22Speaker 01

  I think Hakim's right. We want to find. Life out there. We want to know if we're alone. We want to know, um, how did we get here? We're trying to find the ingredients for biology. So we want to know, are there structures like RNA or DNA out in space? We're getting close. We're finding amino acids. We're finding sugars. We're finding molecules that we find that, that life is comprised of. And so that's very intriguing. We're pushing as hard as we can and technology is taking us one step closer every time we have a new observatory or a new facility that's enabling us to look even harder.

• 9:04Flora Lichtman?

  Look, on a philosophical level, this is what I want, I want your take on. We know that science is about challenging assumptions, being open to outside the box answers. Why does the questioning around this being alien craft rile up the scientific community?

• 9:27Speaker 02

  Oh, man. You know, there, there are cultural issues. You know, I think, you know, we're best when we are open-minded skeptics. I do think we do have to keep an open mind. I've seen a lot of cases over the duration of my own career where you have some new observatory and someone makes an observation or an experiment and they report their results and the scientific community says, hey, even though they've never observed this phenomenon, they say, hey, we know how this really works. We've calculated it and what you observe does not match. Therefore, there's something wrong with your observatory or your experiment.

• 10:01Flora Lichtman?

  Right, right. It, this goes against conventional wisdom and thus it is wrong.

• 10:06Speaker 02

  Exactly, exactly. So I, no, I'm, I'm completely open-minded. I listen to the craziest people.

• 10:13Speaker 02

  But I bring my rigor, my scientific rigor and skepticism along. So do I think that there is life out there? I think it's probably almost certain. Um, but when you get to the level of civilization and technology, that's when the probabilities absolutely plummet. So that is not what I'm expecting, but I am expecting life.

• 10:38Speaker 02

  But not necessarily in this comment.

• 10:42Flora Lichtman?

  You know, setting aside the alien theories for a second.

• 10:45Speaker 02

  Yes.

• 10:46Flora Lichtman?

  This comet has gone viral, which I think is awesome personally. You know, I love to see it. And I'm wondering if you take any meaning from that.

• 10:57Speaker 02

  Oh, I, I, I do. I think that the sizzle around this comet, even if it's about aliens, is a good thing. I think that it is bringing more curious minds to wondering about nature. And, you know, personally, I, my on-ramp to being a scientist, you know, in my youth, included exploring the paranormal, exploring, you know, ghost stories and Bigfoot and no sort of idea. They live in a similar part of the soul and mind, right? That part of curiosity, exploring the unknown, going for that, which is really weird and different. And I think that the attention that astronomy is able to generate, which leads to people,

• 11:42Speaker 02

  right, becoming a part of this enterprise. And this is the on-ramp that gets us there. So I'm all for it.

• 11:49Flora Lichtman?

  Well, bon voyage, 3I Atlas, and good luck, Stephanie. We can't wait to, to hear what you find out. Dr. Stephanie Mylum is an astrochemist at NASA who studies comets and interstellar objects. Thank you for being with us today. Thank you so much for having me. Hakeem, can I hold on to you for one more second?

• 12:04Speaker 02

  Yes.

• 12:04Flora Lichtman?

  We have a listener with a space question, and I'm wondering if you can help.

• 12:09Speaker 02

  I'll try.

• 12:10Flora Lichtman?

  We're going to hear it right after this short break. Don't go away.

• 12:20Flora Lichtman?

  Hey, it's Flora, just reminding you that Science Friday has a dollar-for-dollar donation match right now, meaning that if you make a donation today through December 31st, it will be doubled. So now is the time to head over to sciencefriday.com/support and make a gift. Our 2026 programming depends on your support. That's sciencefriday.com/support, and thank you.

• 12:44Speaker 03

  Support for Science Friday comes from the Heising Simons Foundation. Unlocking knowledge, opportunity, and possibilities. More at hsfoundation.org.

• 12:58Flora Lichtman?

  Okay, here's some of that conversation.

• 13:00Speaker 04

  My name's Michael and I'm calling from St. Louis. My question is, why has the United States and the other countries involved decided to simply throw away the International Space Station by letting it crash into the Pacific Ocean? When there are so many imaginative things that might happen if we did something else? Like, turn the thing loose into deep space? There's so many thrusters on that thing that they could shoot it off into the great unknown and and just let it go. To just throw it away like you're putting it in the recycling bin, you know? It just doesn't make sense.

• 13:42Flora Lichtman?

  What do you see as the advantage of letting it go into the final frontier?

• 13:47Speaker 04

  If some other civilization, you know, if they find it and investigate things about it? Questions like, where's this from? Why is it uninhabited? You know, what was its purpose? And was it intentionally set free from somewhere? Or did it escape? Or did someone lose a war? Or what?

• 14:08Flora Lichtman?

  Forget the golden record, we have a whole home we could send into space.

• 14:13Speaker 04

  Exactly, exactly.

• 14:15Flora Lichtman?

  You see this as an act of generosity to aliens?

• 14:20Speaker 04

  I suppose it is. But I was thinking of it more of an act of a gift to the artists and musicians and poets of the world who would think about this thing just cruising off into whoever knows where.

• 14:34Flora Lichtman?

  The poets on Earth, the Earthlings, the Earthling poets.

• 14:37Speaker 04

  Right, right, right.

• 14:39Flora Lichtman?

  This is a gift to our imagination, actually, is what you're saying.

• 14:44Speaker 04

  To our imagination. Yes, yes. And to the scientists of the foreign universes and galaxies yet to be discovered.

• 14:52Flora Lichtman?

  Okay, well, I want to look into that, if that's okay.

• 14:55Speaker 04

  I'm with you.

• 14:56Flora Lichtman?

  Why don't I do some work and then report back?

• 15:00Speaker 04

  That would be delightful.

• 15:02Flora Lichtman?

  Hakim, okay. I am sure that there are a million and one reasons not to send the ISS out into the great unknown. But can we at least agree that listener Michael has a point here? That this is a romantic option?

• 15:21Speaker 02

  Oh, if it were only so simple. It is a romantic option. And you know what's also a romantic option? Just leaving it where it is in orbit. But even that is far too expensive and dangerous.

• 15:35Flora Lichtman?

  Walk me through it. What are the practical reasons for crashing it into the sea? As opposed to leaving it out in space or sending it into the great unknown?

• 15:44Speaker 02

  You have three options, really, right? So there are what are called graveyard orbits. You boost it up to a higher orbit and it pretty much just stays there orbiting. And even that is too expensive. It's a lot of mass to move. And because of that, you know, it just is prohibitive. And then, once you get there, it becomes a debris risk. Another option is doing nothing. And in that case, it's going to de-orbit naturally, right? Anything in low Earth orbit tends to come down for various reasons. And in that case, it could land on someone. It could land on a crowd of people. You don't want to have an uncontrolled de-orbiting. So the third option is a controlled de-orbiting.

• 16:29Speaker 02

  And that is the option that NASA has selected. That's the least expensive and the safest, right? It's balancing all things.

• 16:38Flora Lichtman?

  Is Michael Wright technologically that you just, that has thrusters on it? You just turn them on and let them go for as long as they go? And then it's out and out on its way?

• 16:48Speaker 02

  No, that is not, I mean, there are thrusters, but they aren't designed to move the entire space station as it is currently assembled. And it wasn't designed to even last this long, right? And it certainly wasn't designed to last indefinitely. And a de-orbit, you know, acceleration kick as a complete body, you know, it's big. So you gotta, you have to get fuel to it. You gotta slap rockets on it. You would have to model that mechanically to understand how to do it. And that's going to cost you millions of dollars. Then when you get to the point of actually trying to do it, that's going to cost you definitely billions, if not hundreds of billions of dollars. And then you're going to have astronauts and potentially cosmonauts involved.

• 17:32Speaker 02

  So you're putting human lives at risk. So there is no really compelling reason to send it out. It's a, it would be nice if, you know, if we had infinite money and infinite resources. Oh yeah, let's undertake this massive, you know, task of making that happen. You know, it's, it's worse than building a pyramid. You know, it's, it's, it's really, really challenging.

• 17:55Flora Lichtman?

  So you're telling me there's a chance?

• 17:57Speaker 02

  Ah, well, here's the thing. If we get that asteroid psyche that is made up of all the precious metal and is worth more than a quintillion dollars, yeah, maybe we could make it happen.

• 18:10Flora Lichtman?

  Dr. Hakim Oluseye is an astrophysicist and CEO of the Astronomical Society of the Pacific. And if you, like Michael, have a burning question for us, or maybe an outside the box idea, we want to hear it. Leave us a voicemail at 8774 sci fry and we'll look into it. This episode was produced by Rasha Aridi. Thank you so much for listening. Happy Friday. I'm Flora Lixman.