\n Published on
\n 03\/11\/2025 – 15:54 GMT+1\n <\/p>\n
When astronomers first spotted 3I\/ATLAS <\/a>on 1 July 2025 using the ATLAS survey telescope in Chile, it was immediately clear that this was no ordinary space rock. <\/p>\n As only the third confirmed interstellar object ever recorded – after \u02bbOumuamua in 2017 and 2I\/Borisov in 2019 – 3I\/ATLAS sparked attention for its icy core enveloped by a coma, the luminous halo of gas and dust. <\/p>\n Its speed and trajectory show that it\u2019s not gravitationally bound to the Sun – meaning it must have originated in another star system and wandered into ours by chance.<\/p>\n While NASA officially identified 3I\/ATLAS as a comet and not an asteroid last week, some scientists, most prominently Professor Avi Loeb, a theoretical astrophysicist at Harvard University, has suggested its unusual features could hint at signs of alien technology.<\/p>\n And as it swooped to its closest point to the sun in late October (perihelion), 3I\/ATLAS began acting in ways that have astronomers scratching their heads again. <\/p>\n Bizarre observations<\/p>\n Most strikingly, the comet experienced a non-gravitational acceleration near perihelion, moving faster than gravity alone would allow. <\/p>\n Observations from the Atacama Large Millimeter Array (ALMA) showed the comet was 4 arcseconds off its predicted trajectory, according to a recent blog post <\/a>by Loeb in Medium. <\/p>\n Ordinary comets are nudged slightly by the gases released from their icy surfaces, but the motion of 3I\/ATLAS was unusually strong. <\/p>\n Meanwhile, its colour shifted dramatically – from a reddish hue to a deep blue – something atypical for comets, which usually redden as sunlight scatters through dust around them. <\/p>\n Astronomers also recorded a sudden brightening in the days before perihelion, suggesting massive amounts of material were being ejected – possibly as surface ice vaporised under the intense solar heat.<\/p>\n Speculation and reactions: From Elon Musk to Kim Kardashian<\/p>\n The unusual behaviour has reignited speculation about whether 3I\/ATLAS could be more than a natural comet. <\/p>\n