3I/ATLAS (formerly known as A11pI3Z) is only the third interstellar visitor to be discovered, and astronomers can’t say yet whether it is a comet or a rocky body.
https://www.nytimes.com/2025/07/02/science/interstellar-object-a11pi3z.html?smid=url-share
Resolution criteria
This market will resolve to the classification assigned to 3I/ATLAS by the International Astronomical Union (IAU) or other authoritative scientific bodies. Possible classifications include:
Comet: If the object exhibits a coma or tail indicative of sublimating ice.
Rocky object (including asteroid): If it lacks cometary activity and is determined to be composed primarily of rock or metal.
The resolution will be based on official announcements from the IAU (likely through its Minor Planet Center), similar organizations, or a clear consensus across space agencies (NASA and ESA) and reputable news sources (NYT, ABC, Washington Post, AP, Reuters). Scientific articles (pre or post peer review) will be moderately weighted toward resolution in case of disagreement.
3I/ATLAS is the third known interstellar object detected passing through our solar system, following 'Oumuamua in 2017 and Comet 2I/Borisov in 2019. Discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS), it is currently near Jupiter and moving toward Mars. Its hyperbolic trajectory and high velocity suggest an origin outside our solar system.
Update 2025-07-04 (PST) (AI summary of creator comment): The creator has confirmed they will wait for more conclusive evidence before resolving the market, rather than resolving based on initial or tentative reports.
Update 2025-07-04 (PST) (AI summary of creator comment): The creator has clarified they will resolve based on the terminology used by major space agencies (e.g., NASA, IAU). If an authoritative body officially refers to the object as a 'comet', that will be the basis for resolution, regardless of whether its orbit matches the traditional definition of a comet (i.e., orbiting the Sun).
Update 2025-07-04 (PST) (AI summary of creator comment): The creator has specified the resolution will be based on the exact term used by authoritative bodies (e.g., NASA, IAU), not its physical characteristics or orbital path.
If an agency confidently calls the object a ‘comet’, it will resolve as such.
If an agency uses terms like ‘exocomet’ or ‘comet-like’, it will resolve to ‘Other’.
Update 2025-07-04 (PST) (AI summary of creator comment): If the authoritative sources listed in the description convey that there is reasonable disagreement or uncertainty about the object's classification, the creator will hold off on resolving the market until a clear consensus has emerged.
1,000@traders Lest you get distracted by the exchange below, orbital trajectory has never been part of the resolution criteria. What matters is what term is used by authoritative agencies to describe the object. If 3I/ATLAS is an interstellar comet unbound to the sun, but e.g., NASA and the MPC confidently describe it as a ‘comet’, then it is a comet for the purposes of this market. If they refer to it as an ‘exocomet’ or a ‘comet-like’ body, but not as an asteroid or other rocky body, then it will resolve to ‘Other’.
I will not rush to resolve. I sold my positions early on and will no longer trade in this market.
https://avi-loeb.medium.com/the-elongated-image-of-3i-atlas-9613a4395772
God, I wish that Avi Loeb's opponents wrote as eloquent blog posts as he did so we could actually evaluate his claims meaningfully.
@bens does this lead you to update upward or downward, given his track record and increasing crankiness?
@MachiNi his track record is fine, tbh; his increasing crankiness is worrisome.
I mean, I'm not really interested in the last section, but I do think it's interesting that evidence doesn't seem to unilaterally support cometary activity. No spectroscopic signature of gases observed. Could just be a large dusty object.
@bens I thought his latest findings about interstellar objects hadn't been well received by his peers? That's all I meant by track record. I know he's an established and respected astrophysicist.
@MachiNi I mean, I think his stuff about 'Oumuamua has earned the ire of his peers, but I would say they've basically ceded the debate to him, in that he's writing serious academic papers defending his perspective and they're basically just calling him crazy without rebutting his work seriously.
Then there's his stuff looking for chunks of interstellar asteroid in the Indian ocean. The first part of that (that an interstellar asteroid probably did impact there) is eminently reasonable and his peers raising doubts about that look pretty silly imo. The second part of that (that he found chunks of it) is pretty absurd and I would be extremely skeptical of his claims there, so that's concerning. However, I think the expedition was worth it, in that it was worth a moonshot attempt to go rescue pieces. I just don't think the random magnetic dust they found was meaningful.
@bens his stuff with Breakthrough Starshot was extremely cool as well and I think that he basically is the only adult in the room (the room being the world) when it comes to thinking reasonably about what an interstellar probe would look like. I kind of don't understand why that project hasn't gotten the sign-off from a billionaire, given that it's probably the most cost-effective space thing that we could be doing right now as far as science or whatever is concerned.
@bens cool. I like your take. I actually liked the guy in interviews and found his peers a little harsh. But he does sometimes look impervious to critique.
@traders Lest you get distracted by the exchange below, orbital trajectory has never been part of the resolution criteria. What matters is what term is used by authoritative agencies to describe the object. If 3I/ATLAS is an interstellar comet unbound to the sun, but e.g., NASA and the MPC confidently describe it as a ‘comet’, then it is a comet for the purposes of this market. If they refer to it as an ‘exocomet’ or a ‘comet-like’ body, but not as an asteroid or other rocky body, then it will resolve to ‘Other’.
I will not rush to resolve. I sold my positions early on and will no longer trade in this market.
@MachiNi hmmm, what if NASA calls it a comet but several very reasonable arxiv posts come out arguing that it's actually something strange, like, a fluffy chunk of interstellar lithium which is very luminous, or an asteroid with a tail of hydrocarbon dust, or idk idk idk
@bens in any case, I'm buying comet shares because the evidence is looking stronger that it is in fact fairly cometary, and also because it would be really fun if it was something more strange
@bens Interesting. If the institutions and sources listed in the description conveyed that there was still reasonable disagreement and uncertainty, then I would hold off resolution until a clear consensus emerged. Make sure to point to such papers if you find them!
@MachiNi ya I think at this point it's unlikely because we've had like 3 independent observations of a tail, but I guess as better telescopes are pointed at this thing, they could find features of it that make categorization more difficult. Also, if it were in fact an alien technosignature (p<<1%) then we won't know until we look at it and see that it's actually like... a giant spacecraft with thrust
@MachiNi ya, now I’m like at 10% that it’s not a comet, although still probably like 0.1% that it’s a technosignature
And for people curious about the difference:
@MachiNi that article is wrong. It says a comet orbits the sun, however that is clearly not the case 😅
Wikipedia:
A comet is an icy, small Solar System body
https://en.m.wikipedia.org/wiki/Comet
All objects other than planets and dwarf planets orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies’
https://en.m.wikipedia.org/wiki/Small_Solar_System_body
NASA:
Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun.
https://science.nasa.gov/solar-system/comets/
ESA:
The Solar System consists of more than just the Sun and the planets. Dwarf planets and so-called ‘small Solar System bodies’ — a term that includes comets and asteroids — also orbit the Sun. This illustration shows three of the best places to go looking for them.
https://www.esa.int/ESA_Multimedia/Images/2023/11/Small_objects_in_the_Solar_System
This seems pretty clear cut to me.
@Odoacre I have a trouble finding a single source about comets not orbiting the sun, so I’m not sure what you’re talking about.
@Odoacre we don’t have evidence of that one way or another yet. I’m just using the terminology that the main space agencies are using. They’re calling it a ‘comet’ for now. The same agencies say comets orbit the sun. I’m not making this up. I didn’t make any claim about the orbit of this particular object. I don’t know what it is, I am just reporting links, and I have said I will wait to resolve.
Actually, the Wikipedia article on 3I/ATLAS now suggests it orbits around the sun:
3I/ATLAS follows an unbound hyperbolic trajectory around the Sun with an extremely high orbital eccentricity of 6.30±0.15.
@Odoacre I recognize the tension but again, I didn’t make up the terms. Take it up with NASA, ESA, and Wikipedia editors, not me, if you don’t like the way they define those terms.
@MachiNi oh, now I see what you mean. I was very confused at one point! Yeah I concede hyperbolic trajectories can still be called orbits. It all started as a joke and then it got worse and worse untilI thought I was losing my mind. Now I feel sane again, thanks!
@Odoacre I was literally just reporting what smarter and more knowledgeable people than me said about this. Don’t shoot the messenger!