By Philip R. Devlin
(October 30, 2025) — First identified by the Atlas telescope in Chile as our solar system’s third known interstellar visitor this past July, (thus the designation “3 i”) our cosmic visitor from another solar system has generated considerable interest recently. Is it a comet as originally thought or is it some kind of alien probe?
Famed astrophysicist Avi Loeb of Harvard University has appeared recently on many radio and TV programs, raising interesting questions and pointing out numerous anomalies about this supposed comet; additionally, numerous YouTube videos proliferate each day, some of which are unusually provocative and conspiratorial in nature. Nevertheless, there are legitimate, interesting aspects of 3 i\ Atlas that arouse curiosity. Here are some of them:
1. Our visitor is zooming through our solar system at an incredible 130,000 mph—much faster than any similar object.
2. Interestingly, its trajectory is on an “ecliptic plane” with all the planets in our solar system, meaning it is following the same plane as the orbits of all of our planets. Loeb places the chances of this trajectory happening by chance at 1 in 500.
3. 3 i \ Atlas is enormous. It is an amazing one thousand times bigger than the previous two interstellar objects that were tracked in our solar system: Oumuamua in 2017 and Borisov in 2019. It appears to be about 5.5 km to 10 km wide. (Its size, interestingly, is similar to the size of an alien spacecraft described in Arthur C. Clarke’s 1971 science fiction novel Rendezvous with Rama.)
4. Its coma (or tail) has several unusual features. First, it is unusually symmetrical; additionally, its outgassing has been estimated as being more than 96% carbon dioxide, a condition never seen before in comets. Furthermore, its coma has a high degree of nickel and no iron—again, an unprecedented observation.
5. All previously observed comets have a tapered tail behind them. At one point 3 i\ Atlas was observed to have its tail in front of it for a while—a phenomenon never previously seen in a comet.
6. This “comet” experienced deceleration between September 23, 2025 and September 26, 2025—an unprecedented event.
7. An attempt to map its surface features using infrared technology resulted in its surface composition matching no known substances.
On October 29, 2025, 3 i\ Atlas reached its closest point to our sun (called a “perihelion”). Astronomers from all over the world are very curious about what effect the heat of the sun will have upon our visitor. December 19, 2025 will be a key date on its journey, as its trajectory will bring it closest to the Earth. We can be sure that all telescopes —both amateur and professional— will be watching, as well as both the Hubble Telescope and the remarkable James W. Webb camera.
