In June, scientists spotted an odd object hurtling toward our solar system. 3I/ATLAS is likely the size of Manhattan. Unlike previous interstellar comets, it has no tail. And now, a Harvard professor says its flight path is highly suspicious.

Avi Loeb is the founding director of Harvard’s Black Hole Initiative, director of the institute for theory and computation the Harvard-Smithsonian Center for Astrophysics, and head of the Galileo Project searching for extraterrestrial technology. All while also being a regular Harvard professor. He theorizes the 3I/ATLAS may be the evidence of extraterrestrial technology he’s been searching for.

The 3 strangest things about 3I/ATLAS

First and foremost, 3I/ATLAS is huge. It’s the largest interstellar object we’ve observed passing through our solar system. Loeb calls it “too large for an interstellar asteroid.” Rock makes up asteroids, not ice. And Loeb argues there probably isn’t enough rock floating in interstellar space to form something like this.

Secondly, it has no tail. Most interstellar objects are partially made of ice–which is the definition of a comet. As they fly toward our sun, they melt a bit and shed a tail of gas. But not this object. “No spectral features of cometary gas are found in spectroscopic observations of 3I/ATLAS.” The chances of something this large being 100% rock are slim to none. So is it made of metal? Or another artificial material?

Finally, there’s 3I/ATLAS’ bizarre flight path. All the planets in our solar system orbit on the same plane around the sun. Some are further away, some are closer, but they are moving in roughly the same direction. Comets always arrive from above or below that plane, often passing through the massive “outer” solar system without ever approaching Earth. Not 3I/ATLAS.

This object is in-line with the orbit of the planets. That will allow it to do a relatively close fly-by of Jupiter, Mars, and Venus. “The retrograde orbital plane of 3I/ATLAS around the Sun lies within 5 degrees of that of Earth… The likelihood for that coincidence out of all random orientations is 0.2 percent.”

Is 3I/ATLAS hiding from humans?

Loeb believes its flight-path alone is reason to be suspicious. “It might have targeted the inner Solar System as expected from alien technology.” And that’s not all. The flight path of 3I/ATLAS is suspiciously sneaky. At its closest point to the sun, it will be hidden from Earth’s view. “This could be intentional to avoid detailed observations from Earth-based telescopes.”

The latest picture of 3I/ATLAS taken by the Hubble Telescope may explain how the object can set its own course. It appears to show 3I/ATLAS glowing. “We do see fuzz, some halo of scattered light around it.” One of Loeb’s theories is that the object is glowing because it’s nuclear-powered. You can learn more about that theory in the video below:

Not everyone thinks 3I/ATLAS is artificial

Richard Moissl is the Head of Planetary Defence at the European Space Agency. He isn’t losing any sleep over our latest extraterrestrial visitor. “There have been no signs pointing to non-natural origins of 3I/ATLAS in the available observations.” And of course 3I/ATLAS is on course to stay far away from Earth.

It’s worth noting that this isn’t the first time Loeb flagged an extraterrestrial visitor as potentially artificial. He theorized that the object astronomers named Oumuamua, which passed through our solar system in 2017, could have been built by an alien civilization. But none of the images captured offered definitive proof, and Oumuamua is long gone.

Loeb urges scientists and world leaders to use all possible resources to study 3I/ATLAS, “The consequences, should the hypothesis turn out to be correct, could potentially be dire for humanity.” It will pass by Mars, where NASA has telescopes in orbit which can snap much better photos, in October.

Moissl doesn’t necessarily disagree, but points out that the scientific community is not ignoring 3I/ATLAS by a long shot. “Astronomers around the world are collecting as much data as possible on the orbit and physical properties of the object and how these change in the course of it passing through our solar system.”