Humans have been investigating potential civilizations in outer space for a long time. According to Professor Avi Loeb (more details Here), an astrophysicist and theoretical physicist at Harvard University, there may be a possibility that 3I/Atlas is actually an alien spacecraft.
I’m guessing you are thinking what 3I/Atlas is. Well, it is a comet. More specifically, an interstellar comet, which means that it is a comet coming from another solar system. This fact alone is super interesting, as we may learn things about our neighbouring solar systems. 3 stands for the 3rd interstellar comet ever detected, and as it was first discovered by ATLAS, it was named 3I/Atlas.
So, why is Prof. Avi Loeb thinking that this could be flown in by other solar systems’ civilizations? He has listed the following anomalies about this interstellar comet:
1: It has come to our solar system using a path that is almost flat with the ecliptic (The plane where our 8 planets move on).
But what does that mean? It means that, although the comet could have come from any random angle, it chose this specific angle, which was very close to our ecliptic. Prof. Avi had said that the other two interstellar comets have entered our solar system with large, random angles and not precise, detailed angles like 3I/Atlas. Also, it would be the best way to examine the planets if he wanted to. The calculations show that taking this angle had a 0.2% chance.
2: It has come very close to the planet Jupiter, Mars and Venus
But, why is this an anomaly? Coming close to 3 planets on its way in our solar system is very unusual considering the whole size of this universe. Also, knowing that all of the planets are always moving in different timings, we can think this like it was planned. What do you think the probability of this happening was? That’s right! 0.005%!
3: ‘It arrived from a direction coincident with the radio “Wow! Signal” to within 9 degrees, with a likelihood of 0.6%‘
This means that 3I/Atlas has come around the same angle as the ‘Wow! Signal’. The 72-second-long Wow signal was detected at the Big Ear Observatory in Ohio, 1977. It was unusual as there was suddenly a burst of very strong radio signals. Prof. Avi is considering whether that signal and 3I/Atlas are related in some ways. (Picture from Wikipedia)
4: During July and August in 2025, the comet was seen with a cometary tail facing the sun.
Usually, cometary tails are held back by the sun because of the solar wind and pressure. We sometimes see this illusion(tail facing the sun) depending on the angle we look at it, but this 3I/Atlas was no illusion. It was strange – how was the tail pointing to the sun? (In this picture from here, the ‘-V’ is where the sun is.)
5: It’s fast! It’s gigantic!
3I/Atlas is roughly the size of Manhattan. It is way larger than the other 2 interstellar comets. The size of its nucleus was a million times larger than our first interstellar comet. It’s also very fast. Prof. Avi has pointed out in his article, ‘The speed of 3I/Atlas before it entered the solar system was about 60 kilometers per second, about 600 times faster than the fastest racing car in the world.’ (see here)
6: The gas plume contained more nickel than iron
What’s wrong with that? Well, the comets we know have an equal amount of nickel and iron and are balanced. We can only find this unbalanced proportion in industrial alloys, but that’s the only place. It’s almost unnatural to have more nickel than iron. It had a possibility of under 1%.
7: The gas plume also contains 4% water by mass.
4% water is very little for a comet. As the comet gets closer to the sun, it burns its materials and normally, most of them is water as comets are a mixture of rock and ice. According to Wikipedia, normal comets have up to 90% of its gas plume to be water. However, this 3I/Atlas had only 4%. Why is there so little water?
8: Around the perihelion, this comet became bluer than the sun
First of all, a perihelion is a point where an object gets closest to the sun when orbiting. And it was shown that at this point, 3I/Atlas became bluer. It’s easier to think that blue means colder. But it actually means that it became much hotter. In fact, it was bluer than the sun – hotter than the sun! How is that possible? Prof. Avi Loeb comments on this during one of his interviews, saying that there were only 2 explanations. (see interviews below! and photo from International Business Times UK)
There are other points that I haven’t mentioned, but you get the idea that 3I/Atlas has some unusual characteristics.
And also, please note this. Most of the scientists have the complete opposite idea to Prof. Avi Loeb. We can expect a lot of weird things from a comet, especially an interstellar comet.
Below are the Quotes that show this.
From Science Alert: In fact, quite the opposite is true: Every piece of evidence collected about 3I/ATLAS to date is consistent with a natural, cometary origin – a highly weird comet, to be sure, but a comet nevertheless.
The Economics Times: American professor Brian Cox has dismissed claims that the cosmic visitor is an ‘alien spacecraft’, calling such theories ‘drivel’.
In this clip(Here), Prof. Avi Loeb is sharing his view on 3I/Atlas and how he thinks about Brian Cox’s idea. He clearly says that “And even if it turns out that it is indeed just a natural object, we could learn much more about the environments that produce such objects, which must be very different from the solar system.” He also says, “My point of view is that this object most likely is a natural comet.” But we don’t have the luxury as we often do in astrophysics to say, “This is the most likely interpretation, let’s forget about any alternative.”
So, what do you think? Something very sure is that this comet has some unique differences from the usual comets that we see. 3I/Atlas will become closest to Earth on the 19th of December this year, and Prof. Avi says that then we can capture a lot more information about this comet.
Source:
https://avi-loeb.medium.com/should-we-be-happier-if-3i-atlas-is-a-comet-91b3f8e74f98
https://arxiv.org/pdf/2510.25035v1
https://arxiv.org/pdf/2507.12213
https://sites.psu.edu/astrowright/2025/11/09/loebs-3i-atlas-anomalies-explained/ (From AstroWright. It would be really interesting to read the opposite perspective!)
Interviews(also reference):
https://www.youtube.com/watch?v=0KrisPhngrw
https://www.youtube.com/watch?v=ZQg5VrkjLj0
https://www.youtube.com/watch?v=4tpC17kOjkA
https://www.youtube.com/watch?v=pQ8tRs1Zg5g
