After 1i / ʻoumuamua and 2i / Borisov, 3i / Atlas is the third object and the second comet from the outside of the confirmed solar system.
This image of the multi-object spectrograph (GMOS-N) of the Gemini North telescope shows the interstellar comet 3i / Atlas. Image credit: International Gemini Observatory / Noillab / NSF / AURA / K. MEECH, IFA & U. HAWAII / JEN MILLER & MAHDI ZAMANI, NOIRAB.
3i / Atlas was discovered by the latest alert system (Atlas) funded by the asteroid funded by NASA on July 1, 2025.
Also known as C / 2025 N1 (Atlas) and A11PL3Z, the comet arrived from the management of the Sagittarius constellation.
Its orbit is the most dynamic extreme of any object still recorded in the solar system.
“It is perhaps not foreigners who establish the first contact, but 3i / Atlas, as only the third interstellary object documented to cross the solar system, still has a lot to teach us,” said the astronomer of the Northeast University, Jacqueline McCleary.
“Interstellar objects, which all seem to be comets, are the only things for which we have never obtained physical observations within our solar system which is from the solar system. It is a bit like a messenger from afar.”
“There are so few interstellar objects that we have detected in our solar system, and they each seem unique,” said the astronomer of the State University of Michigan, Adina Feinstein.
“3i / Atlas gives us the opportunity to study other near and personal solar systems, without needing to visit them.”
As astronomers discovered 3i / Atlas, it was clear that it was not a normal comet. To start, he seemed to emit his own light, which is bizarre for a comet who was, at the time, so far from the sun.
Compets are normally extremely dark to the point where astronomers find it difficult to see them.
As they get closer to the sun, solar radiation causes volatile compounds and exterior ice creams, which are very reflective, to melt.
The resulting effect is, at the beginning, a kind of proto-tail called a coma, which grows in the tail that we have come to associate with comets that cross the night sky.
“Jupiter is 5 at or five distances from the Earth of the Sun, and most comets must get closer to that of solar radiation to become intense enough to start this creation of a melting and missing tail,” said Dr. McCleary.
“The comet 3i / Atlas formed a coma when it was outside the orbit of Jupiter, at a distance much greater than normal.”
For 3i / Atlas, having started to shine as far from the sun as he did was abnormal enough to cause a very early theorization that he must be an extraterrestrial spacecraft. What would it be small and fast would produce light?
However, subsequent observations revealed that he had not only a comet tail, but that it was probably rich in carbon dioxide “because carbon dioxide ice cream, AKA dries, very easily bottom
The NASA / ESA / CSA James Webb space telescope finally revealed that the comet was unique for reasons that went beyond her interstellar origins.
Not only was it made of carbon dioxide, but it had an ice cream ratio with carbon water which was literally out of this world, 8: 1, which is among the highest registered.
It offers a potential overview of the conditions that exist in other solar systems and how these systems have been formed in the first place.
“Obviously, the 3i / Atlas parent system was perhaps really rich in carbon dioxide or perhaps there were strange radiation processes that left a lot of carbon dioxide and boiled everything else,” said Dr. McCleary.
“Indirectly, try to understand the composition of this comet and compare it to the composition of other interstellar comets … can tell us what the formation of the solar system looks like in other solar systems at a really granular level.”
We still do not know where 3i / Atlas comes from.
“It probably came from the bulge of the Milky Way, but the tracing of its exact origin will be difficult,” said Dr. McCleary.
“In order for him to escape her parental solar system, the comet must have encountered a gravitational disturbance which disturbed her orbital path and put it on the right track to enter our solar system.”
However, scientists could have an even more detailed overview of the comet when he crosses Jupiter’s orbit on her path linked after October, revealing more about his nature.
The Juno satellite in orbit Jupiter of NASA will be in the best position to put eyes on the interstellar visitor.
“We could potentially have an overview of this comet, and it could be particularly interesting, because it will have gone as close to the sun as to obtain it and a lot of carbon dioxide will have boiled … So we will be able to see what remains,” said Dr. McCleary.
Find out more about 3i / Atlas will not only be useful to understand what other solar systems look like, but why our solar system is so unique that it has created the conditions for sensitive life.
“It is a window on what the virgin material is for other solar systems, which is precious and, in turn, helps us to refine our models of the formation of the solar system,” said Dr. McCleary.
“Is our solar system common or rare?” It seems to be relatively rare, and it helps us to quantify this. ”
“Learning other solar systems puts humanity in the context,” said Dr. Feinstein.
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“Capture as many observations of the pre-crushing period, where 3i / Atlas can be in the images of the telescope but has not been identified before, is essential to our understanding of how these objects come on” as we approach our sun, “said the astronomer of Auburn University, John Noonan.
“These interstellar objects have probably not been considerably warmed in millions, even billions, years, and any opportunity to see how they responded to this early heating are interesting.”
