This is not the post I was planning to write but as the mystery over Comet 31/ATLAS deepens, this interstellar visitor grows more intriguing.
The Stealth Comet
If you haven’t heard of 31/ATLAS, it may be because the mainstream media ignore it in favor of political stories. Or, possibly, we just don’t have any news coming from NASA while the government is non-functional. But that doesn’t change the fact that it’s out there, it’s still coming toward us, and we still don’t know what exactly it is.
Technically, the object is called Comet 31/ATLAS but it is unlike a typical comet in several striking ways. Even though we are still calling it a comet, it is a true cosmic outsider. Here’s are the many ways in which it stands apart:
Interstellar Origin
3I/ATLAS does not come from our solar system. It’s only the third known interstellar object ever observed, after 1I/ʻOumuamua (2017) and 2I/Borisov (2019). That means it doesn’t come from the Kuiper Belt or the Oort Cloud. If it doesn’t originate in the solar system, that means it’s coming from deep space. In fact, it’s coming from the direction of the constellation Sagittarius, potentially from the Milky Way galaxy’s thick disk, which primarily contains older stars.
The Oort Cloud
Blazing Speed
Comet 3I/ATLAS is moving at a speed that’s wildly beyond the norm for solar system comets—because it’s not from around here. It’s speed at infinity clocks in at ~57 km/s (source: Oxford Academic), whereas a typical solar system comet’s speed registers ~10–40 km/s depending on its proximity to the Sun and orbital eccentricity. That 57 km/s figure represents its velocity before gravitational acceleration by the Sun—meaning it was already blazing through interstellar space at that speed.
Once it enters the solar system, it accelerates even more due to solar gravity. Because it’s a visitor from another star system and not a long-period comet from the Oort Cloud. it’s carrying momentum from a completely different gravitational environment
The object’s hyperbolic trajectory (eccentricity ≈ 6.1) confirms it’s not gravitationally bound to the Sun because it’s going too fast. The hyperbolic orbital path means that it is simply passing through our solar system before continuing on its journey back into interstellar space.
The Kuiper Belt
Detection and Rarity
Discovered on July 1, 2025, by the ATLAS telescope in Chile, its odd motion immediately attracted attention. Interstellar objects are extremely rare—only the three listed above have ever been confirmed despite decades of sky surveys. 31/ATLAS also has a path that is sharply curved, unlike the elliptical path followed by typical comets. That represents a hallmark of interstellar visitors.
Scientific Significance
Unlike solar system comets, which formed from the same primordial disk as Earth, 3I/ATLAS carries material from another star system. Studying it offers a rare glimpse into alien planetary formation. It may contain chemistry or isotopic ratios never before seen in our solar system.
No Return Visit
Normal comets often return periodically (e.g., Halley’s Comet every 76 years) but 3I/ATLAS appears to be a one-time visitor. It will slingshot past the Sun and vanish back into interstellar space.
Unusual Composition
The James Webb Space Telescope has analyzed 31/ATLAS as rich in carbon dioxide and water ice. This suggests that it formed much farther from its parent star than other comets. Each of the previous interstellar visitors has also registered dramatically different chemical compositions.
Peculiar Tail Behavior
During its approach to the sun, the object displayed an unusual “backward” dust plume that pointed it toward the sun instead of away from it. The solar wind blows the tails of typical comets away from it. Astronomers concluded from the lack of gravitational acceleration that 32/ATLAS’s nucleus must be larger and more massive that they had initially estimated.
Only the Ones We Know
Astronomers so far have analyzed the surveys of 31/ATLAS with the assumption that it is a comet, if not one that we are accustomed to observing. This is the mundane approach, one that insists on viewing something new in the context of everything that has gone before while ignoring or downplaying anomalies. Astrophysicists will cram this object into the Procrustean Bed of a comet’s profile regardless of whether it fits.
These three objects are not the only interstellar visitors to have entered our solar system—they are just the only three that we know about. Others like them could, unknown to us, have been coming and going for millennia. They may have been in the sky while the Druids were painting themselves blue, while the Greeks defeated the Persians at Marathon, while Henry VIII was marrying yet another wife, and while Chaco Canyon was a thriving community.
Now Comes Something Completely Different
But what if 31/ATLAS is actually something completely different? Assuming that it is a comet can blind us to the reality of a unique object approaching Earth. That means we could miss important information that doesn’t fit easily into the definition of a comet.
The AI-generated illustration below gives us an idea of the different interstellar trajectories but is probably not scientifically accurate.
The reactions to these anomalies illustrate the differences between mundanes and fantastics. Fantastics love the unknown and find mysteries exciting while mundanes are firmly tethered to reality and feel threatened by the unknown. The online comments from this type of person dismiss the unusual aspects of 31/ATLAS without providing any scientifically proven explanations for them.
Emerging from Behind the Sun
More news about 31/ATLAS appears regularly. I plan to discuss them in a further post. One way or the other, one side of the debate about the interstellar object’s origins will be vindicated. In the meantime, we wait for the “comet” to emerge from behind the sun in December and become visible to Earth-based telescopes. Then we should learn more.
Interstellar Trajectories
Below is an AI-created model of the solar system that shows the paths of the three interstellar objects. Despite the labels, 31/ATLAS us the comet with the bright tail. You can easily see how they don’t follow a “normal” comet’s elliptical path. 
Explanation
