UFO or comet? NASA weighs in on a mystery object

An unusual find. What the telescopes showed

The object stirring up intense emotions is 3I/ATLAS. It was first spotted in early July 2025 and immediately caused an uproar in the scientific community. Initially, researchers said outright that it was a comet. Then physicist and astronomer Prof. Avi Loeb, who leads the Galileo Project at Harvard — an initiative focused on the search for intelligent life beyond Earth — joined the discussion. Less than a month after 3I/ATLAS was discovered, Loeb, together with Adam Hibberd and Adam Crowl, posted a paper on arXiv titled Is the Interstellar Object 3I/ATLAS Alien Technology? The professor suggested we might be looking at a product of extraterrestrial technology. The debate flared: UFO or comet?

Read more: Is It a Comet or an Alien Spacecraft? Harvard Scientist Suggests Extraterrestrial Technology

UFO or comet? A clash among scientists

Loeb argued that 3I/ATLAS was not behaving like a typical comet. It lacked the hallmark tail of dust and plasma seen in such objects. In addition, it travels on a rarely observed retrograde orbit, crossing Earth’s orbit at an angle of 5 degrees. Loeb also pointed to its large size — measurements available at the time indicated about 20 kilometers in diameter, which is substantial for an interstellar comet.

NASA cools the hype. An expert explains what 3I/ATLAS is

As we reported in early August, the European Space Agency has been highly skeptical of Loeb’s claims. More recently, a NASA researcher also weighed in. The Guardian contacted Tom Statler, NASA’s lead scientist for small bodies in the Solar System. According to Statler, beyond any reasonable doubt we are dealing with a comet.

“It has interesting properties that set it a bit apart from comets in our Solar System, but it behaves like a comet. Therefore, the evidence clearly indicates that this object is a natural body. It’s a comet,” the NASA expert said.

So why the missing tail and the unusual trajectory? Statler notes that comets originating outside our system can behave unpredictably under the Sun’s heat. It’s also worth stressing that, based on astronomers’ calculations, the object will approach Earth no closer than about 273 million kilometers.

UFO or comet? How close will the object get to Earth?

What about the body’s unusual size? In his calculations, Loeb relied on preliminary data. NASA’s latest observations, however, estimate 3I/ATLAS at just 5.6 kilometers in diameter, not 20 kilometers as the astronomer proposed. It’s worth noting that even if this is not a spacecraft, 3I/ATLAS remains an intriguing object.

The comet is moving at a record-setting speed for something entering our system from the outside: 209,000 km/h. While it will not pass particularly close to Earth, it is expected to swing by Mars, Jupiter, and Venus at relatively short distances. In the meantime, Loeb acknowledged on his blog that the comet hypothesis is indeed the most likely. His paper, he said, was meant to present an alternative possibility as an exercise in challenging entrenched assumptions.

Read the original article: UFO w Układzie Słonecznym? NASA rozwiązała zagadkę