Harvard astrophysicist Professor Avi Loeb has renewed global attention by proposing that 3I/ATLAS, an unusual interstellar object, might actually be an alien spacecraft, potentially reaching Earth in roughly 116 days. While the mainstream scientific community continues to consider it a comet, Loeb’s hypothesis has sparked intense debate.
3I/ATLAS, officially designated C/2025 N1 (ATLAS) and discovered on July 1, 2025, travels at speeds around 130,000–140,000 mph and follows a hyperbolic trajectory that places it among just three known objects that originated outside our solar system WikipediaThe Economic TimesFox News.
Loeb and team suggest the object’s path, speed, and unusual glow pattern—particularly a bright sun-facing halo rather than a classic comet tail—could indicate artificial origin, possibly even a nuclear-powered mothership releasing smaller probes, some of which might reach Earth as UAPs (Unidentified Aerial Phenomena) Fox NewsMediumNew York PostDaily Express US.
Their preprint paper argues that the object’s orbit aligns closely with the orbits of Venus, Mars, and Jupiter—a configuration with a probability of just 0.005% if natural. Loeb posits this could allow a visiting intelligence to discreetly deploy devices on or near those planets or even near Earth, especially during its perihelion in late October 2025, when the object will be obscured behind the Sun from Earth-based observers Live ScienceWikipediaNew York PostThe Sun.
Loeb emphasizes their hypothesis as speculative but testable. He supports redirecting existing spacecraft—such as NASA’s Juno or Mars Reconnaissance Orbiter—toward 3I/ATLAS to gather data as it passes near Jupiter in March 2026 ChronMedium.
In contrast, many experts firmly assert that 3I/ATLAS is an interstellar comet. Observations by NASA, James Webb Space Telescope, Very Large Telescope, and other facilities detect a coma rich in carbon dioxide, carbon monoxide, water ice, cyanide, and atomic nickel—typical clues of a naturally occurring icy body MediumarXiv+1Wikipedia. Scientists including Samantha Lawler and Chris Lintott reject the alien probe theory as highly unlikely and say the object poses no threat, expected to pass at a safe distance from Earth (at least 1.8 AU) Live SciencePeople.comThe Times of IndiaNew York Post.
Loeb himself acknowledges the most probable outcome is that 3I/ATLAS is a natural comet, but insists we must “put all possibilities on the table” until firm observational data emerges CBS NewsPeople.comLive Science.
Important observations loom: high-resolution imaging and spectral data from Hubble, JWST, and Earth telescopes are underway, and Mars Reconnaissance Orbiter may capture key images during a close pass on October 3, 2025, helping estimate the nucleus size and determine whether the object behaves like a comet or something more extraordinary MediumChronWikipedia.
As 3I/ATLAS speeds toward inner solar system, set to reach perihelion on October 29–30, 2025, the scientific world watches closely. Will it confirm Loeb’s provocative hypothesis, or simply be another fascinating interstellar wanderer?
