The Mystery of Comet 3I
- Juan-Pablo Pina
- 6 minutes ago
- 4 min read
by Juan-Pablo Pina
Space has always been an intriguing field for humans, from its horrors to its wonders.
But what may be even more interesting are its mysteries. One such mystery is the new stellar object nicknamed “Comet 3I/ATLAS” that was first spotted on July 1st of 2025 by NASA and has been puzzling scientists since. And on November 19th of 2025 at 3:00 P.M EST., NASA will be hosting a livestream where the public can observe it alongside scientists.
What We Know
So what do we know about “Comet 3I/ATLAS” (or simply “Comet 31”)?
For one, its name comes from the fact its the third (3) interstellar (I) object found, while “ATLAS” comes from the telescope with which it was found (the ATLAS, “Asteroid Terrestrial-impact Last Alert System”, Telescope). We know that Comet 3I is the third known object from outside our solar system to be discovered passing through our celestial neighborhood. When the orbit of Comet 3I is traced into the past, the comet clearly originates from outside our solar system.
Is the comet going to hit Earth? Most likely not. Comet 3I poses no threat to Earth and will remain far away. The closest it will approach our planet is about 1.8 astronomical units (about 270 million kilometers). In fact, Comet 3I already reached its closest point to the Sun around Oct. 30, 2025, at a distance of about 1.4 au (210 million kilometers) — right beside Mars. The interstellar comet’s size and physical properties are being investigated by astronomers around the world. Comet 3I was visible to ground-based telescopes through September 2025, after which it passed too close to the Sun to observe. It will reappear on the other side of the Sun by early December 2025, allowing for renewed observations.
Based on observations from NASA’s Hubble Space Telescope on Aug. 20, 2025, astronomers estimated the diameter of Comer 3I’s nucleus (the actual object itself, not the trail of debris) to be not less than 440 meters and not greater than 5.6 kilometers.When it was discovered, Comet 3I was traveling at about 221,000 kilometers per hour. Pulled by the Sun’s gravity, its speed increased to about 246,000 kilometers per hour at its closest approach to the Sun, known as perihelion. When Comet 3I leaves our solar system it will be at the same speed as it came in.
Comet 3I formed in another star system and was somehow ejected into interstellar space, which is the space between the stars. For millions or even billions of years, it has drifted until it recently arrived at our solar system. It has been approaching from the general direction of the constellation Sagittarius, which is where the central region of our galaxy, the Milky Way, is located. It does not follow a closed orbital path around the Sun. It is simply passing through our solar system and will continue its journey into interstellar space, never to be seen again. From telescope observations, astronomers can tell that Comet 3I is active, which means it has an icy nucleus and a coma (a bright cloud of gas and dust surrounding a comet as it approaches the Sun). This is why astronomers categorize it as a comet and not an asteroid.
What We Don’t Know & How YOU Can See It!
So what’s the mystery?
The mystery surrounding Comet 3I is its unusual lack of a tail, the tail being the trail of debris that follows a comet or asteroid. What makes it even weirder is that it lacks a tail despite getting close to the Sun. And while most scientists believe it is a natural comet, its odd characteristics have led to speculation, though there is no evidence that it is an alien spacecraft. A Harvard scientist, who believes he’s seen proof of alien life before, suspects this object may instead have alien origins.
Professor Avi Loeb said there are clear signs that Comet 3I could be an alien craft. “We should put all possibilities on the table that it’s a rock, a comet, or something else until we get the evidence, the data that will tell us what it is,” Loeb said in an interview with WBZ-TV. Professor Loeb also said “I think that when we have a blind date from a visitor from another star, all bets are off. We shouldn’t assume anything, and we should assess the risk given the data that we have.”
Loeb said the risk should be assessed using something like the Richter scale for earthquakes. “Zero would be a natural object like a comet,” Loeb said. “Ten would be an object that maneuvers as if it has an engine that is definitely technological, and then there should be some policymakers deciding how to respond to that.”
Professor Loeb also addressed the potential of an alien origin. “We see a lot of houses on the cosmic street that look just like ours, analogs of the Earth’s sun system,” Loeb said. “And I think it’s very arrogant of us to assume that they don’t have residents.”
But how can you see Comet 3I and maybe even help us learn more about it? NASA will host a live event at 3 p.m. EST, Wednesday, Nov. 19, to share imagery of the interstellar comet 3I/ATLAS collected by a number of the agency’s missions. The event will air on NASA+, the NASA app, the agency’s website and YouTube channel, and Amazon Prime.
NASA participants include:
NASA Associate Administrator Amit Kshatriya
Nicky Fox, associate administrator, Science Mission Directorate
Shawn Domagal-Goldman, acting director, Astrophysics Division
Tom Statler, lead scientist for solar system small bodies
Members of the public also may ask questions, which may be answered in real time during the broadcast, by using #AskNASA on social media as Comet 3I continues its rare journey through our solar system.
Whether it turns out to be a perfectly natural visitor or something that challenges our assumptions, its passage offers scientists—and now the public—a unique chance to learn more about the cosmos. And with NASA’s upcoming livestream, anyone can take part in witnessing this natural wonder in real time.