Mystery object hurtling towards Earth behaves just like an ‘alien spacecraft’, experts say
Theoretical physicist Avi Loeb has warned it could be an ‘extraterrestrial artefact’ which may be about to make first contact as it was seen ‘braking’ and ‘shedding’
18:37, 23 Oct 2025
An image captured by NASA in July when the comet was still nearly 3 million miles from Earth(Image: AP)
Astronomers are stunned after a mystery object hurtling through space performed a manoeuvre just like an ‘alien spacecraft’ braking. Most experts were convinced 3I/ATLAS was a comet bursting through the Solar System at 130,000mph.
But theoretical physicist Avi Loeb has warned for months it could be an ‘extraterrestrial artefact’ which may be about to make first contact.
Avi, 63, a professor of science at top US university Harvard where he is director of the Institute for Theory and Computation at the Center for Astrophysics, said the object’s unique characteristics meant it may not be natural and could have been sent towards Earth by ET.
Now boffins tracking the interstellar visitor have revealed it has performed a dramatic tail reversal – and is now pointing away from the Sun.
The 3I/ATLAS interstellar comet is whizzing through our solar system(Image: X)
The change comes weeks after Hubble Space Telescope images captured it with an unusual ‘anti-tail’ – a jet of particles streaming towards the Sun. New high-resolution observations from the Nordic Optical Telescope in the Canary Islands confirm the anti-tail seen in July and August has vanished.
A new one has formed in the opposite direction. Researchers at the Universities of California and Oslo found 3I/ATLAS is shedding material as solar radiation strikes its surface.
NASA’s space telescopes had detected it losing about 330lbs of material per second made up of 87% carbon dioxide and 9% carbon monoxide.
The mysterious interstellar object speeding past Mars has been spotted shedding metals(Image: NASA)
Further ground-based observations will be impossible this month as the object will be hidden from Earth’s view as it passes behind the Sun. Professor Loeb said it was not yet possible to determine what the object was.
But it could still be an historic UFO. He said: “We cannot infer the true nature of 3I/ATLAS from the skin layer it has shed so far.
“If the object were an alien spacecraft slowing down, and the anti-tail represented braking thrust, this shift from anti-tail to tail would be entirely expected.”
It is only the third interstellar object humanity has detected following ‘Oumuamua in 2017 and 2I/Borisov two years later.
Avi Loeb(Image: Anadolu Agency via Getty Images)
But Professor Loeb said 3I/ATLAS was behaving in a unique way. ʻOumuamua showed no signs of gas or dust. 2I/Borisov behaved like a normal comet.
But 3I/ATLAS has displayed never-before-seen features including its anti-tail, extreme colour changes and a massive surrounding coma – a haze of gas and dust around the nucleus.
Professor Loeb said the period the object was hidden from Earth’s view would be ‘an opportune time for technological action’ if it is being controlled from afar.
Aliens could be planning first contact(Image: Getty Images/Science Photo Library RF)
He said in space travel the best time to speed up or slow down a craft was when it was closest to a large object since firing the engine at that point – known as the Oberth effect – gives the biggest change in speed.
“If 3I/ATLAS is a massive mothership it will likely continue along its original gravitational path and ultimately exit the Solar System,” he said.
“In that case the Oberth manoeuvre might apply to the mini-probes it releases towards Solar system planets.”
3I/ATLAS will reach its best window for such manoeuvres eight days after it slips behind the Sun when it is within 126 million miles.
Professor Loeb said he hopes the mystery is solved on December 19 when the object makes its closest approach to Earth.
But whatever happens its behaviour has been so odd he said he will never be able to rule out the possibility it is an alien craft.
On his UFO scale where zero represents something ‘consistent with known natural phenomena’ and 10 is of ‘confirmed extraterrestrial origin’ he said 3I/Atlas would always at least be a two – an object ‘meriting attention’.
