Our solar system’s third identified interstellar intruder, 3I/ATLAS, continues its course past the planets more-or-less within the plane of the ecliptic, and continues to surprise.
The least surprising thing is that it has finally developed a tail pointing away from the Sun:
On August 27, 2025, deep imaging of the interstellar object 3I/ATLAS by the Gemini South 8.2‑meter telescope — aided by the Gemini Multi-Object Spectrograph (GMOS), revealed a weak tail with a teardrop shape in the anti-Sun direction (reported here). At that time, 3I/ATLAS was at a distance from Earth of 2.59 times the Earth-Sun separation. The Gemini South Observatory is located on a mountain called Cerro Pachón in the Chilean Andes.
Avi Loeb, “Detection of an Anti-Solar Tail for 3I/ATLAS,” Medium (August 30, 2025).
Earlier observations had not seen the usual tail forming away from the point of origination of the solar winds, like a normal comet. Instead, the “coma” of dust or ice or gas or whatnot surrounding the object extended in advance of its trajectory — as if it were throwing out flak to take out dangerous objects ahead of it!
Yes, from the beginning the oddities of this intruder were being considered as possible indications of an artificial object.
While this is heartening for those who itch to relegate 3I/ATLAS to “mere” comet status (it’s already proved to be one weird comet, it comet it truly be), Abraham Loeb notes the accumulating oddities, too, which don’t fit the standard “nothing [challenging] to see here, folks” debunkers’ designations: “Recent spectroscopic data from the Very Large Telescope in Chile (accessible here), reported the surprising detection of cyanide and nickel without iron in the plume of gas around 3I/ATLAS with steeply increasing rates as the object approaches the Sun. Nickel without iron is a signature of industrial production of nickel alloys. Natural comets generically show iron and nickel simultaneously, as both elements are produced simultaneously in supernova explosions.”
And as Loeb just noted, measuring the nucleus of the object remains extremely difficult and uncertain.
Further, though detection of CO2 in the object’s coma (surrounding matter) is indeed what one would expect of a comet, the absence of water and carbon monoxide is … peculiar.