A Harvard astrophysicist has sounded the alarm over an interstellar object hurtling toward Earth, warning humanity is unprepared if it turns out to be alien technology.
Professor Avi Loeb, known for his controversial theories on extraterrestrial intelligence, has published three pre-print studies since the detection of the object, dubbed 3I/ATLAS, on July 1, 2025.
His analysis suggested the object is significantly larger than typical interstellar debris, shows no signs of cometary gas and is on a path that will take it unusually close to Venus, Mars and Jupiter.
‘In case 3I/ATLAS represents a spacecraft of 20-kilometer size, we should worry about its intent,’ Avi said.
‘At its closest approach to the sun on October 29, 2025, the stock market might crash if fears of an alien invasion skyrocket. In that scenario, citizens would lose their trust in governments to protect them.’
Loeb compared the potential panic to a military standoff: ‘Facing a high-tech alien visitor could feel like Iran‘s air defenses when US B-2 bombers appeared, silent, unstoppable and far outmatched.’
However, not everyone is so convinced. Chris Lintott, an astronomer at the University of Oxford, told Live Science: ‘Any suggestion that it’s artificial is nonsense on stilts.’
He added that these claims are an ‘insult to the exciting work going on to understand this object.’
Telescopes have been tracking the course of 3I/ATLAS as it travels through our solar system. Harvard scientist Avi Loeb has speculated that it could be an alien probe and not a comet as many researchers have found
A scene from the Book of Eli shows what Earth would look like if the apocalypse came
However, Loeb insisted the anomalies warrant investigation, not ridicule.
‘I laid out this possibility in order to encourage observers who are convinced that 3I/ATLAS is a comet to collect as much data as possible in an attempt to prove me wrong,’ he said.
‘In the presence of ample data, there will be no leeway for them to shove anomalies under the carpet of conventional thinking.’
The professor also predicted that ‘An optimal intercept of Earth would entail an arrival in late November or early December of 2025
What makes 3I/ATLAS so unusual, Loeb argued, is its trajectory, passing behind the sun from Earth’s perspective, which he speculates could provide cover for deploying smaller probes toward Earth if it’s an artificial craft.
Referring to the object as a ‘mothership,’ he explained that its position would be an efficient way to seed habitable planets with probes.
This strategy would allow the devices to ‘intercept the planets while the mothership continues on its journey to the next star.’
‘It may come to save us or destroy us. We’d better be ready for both options and check whether all interstellar objects are rocks,’ said Loeb.
The arrival of 3I/ATLAS has presented a different challenge than the distant alien signals sought by SETI researchers for more than six decades.
Loeb has warned humanity is dangerously unprepared if hat if 3I/ATLAS is alien technology
Loeb compared the potential panic to a military standoff: ‘Facing a high-tech alien visitor could feel like Iran ‘s air defenses when US B-2 bombers appeared, silent, unstoppable and far outmatched’
Unlike a radio transmission from a far-off star system, which gives humanity time to consider a response, a physical object entering our solar system leaves little time to act.
Loeb warned that if 3I/ATLAS is not a natural comet or asteroid but a functioning spacecraft, ‘the visitor is already in our backyard.’ And Earth is unprepared.
Even if 3I/ATLAS turns out to be artificial, Loeb said humanity lacks the technological means to intercept it.
The object’s speed at perihelion, its closest approach to the sun, will be nearly 60 miles per second, far beyond the capabilities of chemical rockets.
And its ‘clocking’ move behind the sun will make it impossible for Earth-based telescopes to observe.
‘The protocol on how to respond to an alien threat depends on the nature and intent of the associated spacecraft,’ said Loeb.
‘There is no international organization ready to make a global decision on how to engage with 3I/ATLAS, should it be an alien spacecraft.’
He has proposed a standardized alert scale for interstellar objects, similar to the Richter scale for earthquakes.
On such a scale, a harmless comet would be a zero, while confirmation of alien technology could rate a ten.
‘This isn’t just a matter for one country,’ Loeb emphasized. ‘If the next object is a probe, all of humanity will be affected. We must be ready to act, together.’
While Loeb has suggested alternative ideas for what 3I/ATLAS could be, a team of more than 200 researchers said it is more likely to be a comet.
They identified the object’s coma, the cloud of ice, dust and gas surrounding it, which Loeb determined was not present.
