What is 3I/ATLAS? Here's what NASA says about this rare interstellar visitor

[Buster's Uncle]

What is 3I/ATLAS? Here's what NASA says about this rare interstellar celestial visitor
Iris Seaton and Eric Lagatta, USA TODAY NETWORK
Asheville Citizen-Times
Mon, October 6, 2025 at 7:16 AM EDT
3 min read



The Hubble Space Telescope captured this image of interstellar object 3I/Atlas in the outer solar system.


Rare interstellar visitor comet 3I/ATLAS has made headlines and caught the attention of the public for months.

The object is one of only three space objects originating from a star other than our sun to be spotted in Earth's cosmic neighborhood. Such an event, which is rare enough to spark interest on its own, has also given way to plenty of wild ideas about what it could be - including the infamous theory that 3I/ATLAS could be an alien spaceship.

For scientists around the world, the discovery that 3I/ATLAS is making a short journey into and out of our solar system has sparked an urgency to get a closer look at an object that could soon vanish from our sight. Early on, astronomers were able to determine with a high degree of certainty that the object is a comet, but work has continued to get a better idea of its size and physical characteristics.

NASA's iconic Hubble Space Telescope previously got a look at the comet in July, collecting data that allowed astronomers to estimate the size of the comet’s solid, icy nucleus as anywhere from 1,000 feet to 3.5 miles wide. Orbiters around Mars and Jupiter will soon have another opportunity to observe the object, according to the European Space Agency.

Here's what else we know about the object for astronomy fans.


What is comet 3I/ATLAS?

A comet known as 3I/ATLAS made news in July when it was confirmed to have originated outside Earth's solar system. When it was discovered, the interstellar comet was moving at about 137,000 miles per hour - and it's expected to continue picking up speed as it continues its journey toward the sun.

The Minor Planet Center, an official authority for observing and reporting new comets and other small bodies in the solar system, recorded the comet's observation. The object, which was eventually confirmed to almost certainly be a comet and named 3I/ATLAS, was later confirmed to have interstellar origins.


How did 3I/ATLAS get its name?

3I/ATLAS is named for its status as one of three interstellar objects ever discovered in our cosmic neighborhood, as well as for the NASA-funded telescope that spotted it: ATLAS, short for Asteroid Terrestrial-impact Last Alert System.


What was the first interstellar object detected in the solar system?

Comet Oumuamua, Hawaiian for “scout” or “messenger,” became the first interstellar object ever detected in the solar system in 2017, followed by the comet Borisov in 2019.


How close will 3I/ATLAS get to Earth?

The closest 3I/ATLAS will approach Earth is about 170 million miles, according to NASA.

The object will instead pass a little closer to the sun, coming within 130 million miles on Oct. 30. For reference, the sun is about 93 million miles away from Earth.


Will object 3I/ATLAS be visible from Earth?

As of now, the comet is on the opposite side of the sun from Earth, making it impossible to observe from the ground. The object will reappear in December on the other side of the sun, making it visible once again.


Is 3I/ATLAS an alien spaceship?

While 3I/ATLAS is confirmed to "almost certainly be a comet," some researchers have speculated on whether the object could be "hostile" alien technology.

Avi Loeb, an astrophysicist from Harvard University, authored a paper with two others on the subject, which was uploaded on July 16 to the preprint server arXiv. USA TODAY reported the Loeb "has long had a preoccupation with extraterrestrials," even co-founding the Galileo Project, a research program at the Harvard-Smithsonian Center for Astrophysics dedicated to the search for alien life.

Others, however, have pushed back on some of Loeb's bolder claims. For instance, when the first interstellar object ever detected in our solar system was spotted in 2017, Loeb similarly posited that it was of extraterrestrial origin - a theory that was later debunked.

Eric Lagatta, USA TODAY, contributed to this report.

Iris Seaton is the trending news reporter for the Asheville Citizen Times, part of the USA TODAY Network. Reach her at iseaton@citizentimes.com.

This article originally appeared on Asheville Citizen Times: What is comet 3I/ATLAS? What to know about interstellar visitor