3I/ATLAS, only the third object known to have entered our solar system from interstellar space, was discovered on July 1, 2025, by the ATLAS survey telescope in Chile. By January 2026 it was heading back out, and astronomers were grabbing last looks. NASA’s TESS satellite interrupted its regular survey to watch it from Jan. 15 to 22. On Jan. 22 the comet lined up within 0.69 degrees of the Sun-Earth axis, a geometry that may not repeat for decades, and Hubble observed it that day.

Processing Hubble images from January, Loeb’s collaborator Toni Scarmato found a system of jets: a prominent anti-tail pointing nearly toward the Sun, plus three mini-jets spaced 120 degrees apart. In a Medium essay that week, Loeb asked whether that symmetry could be a technological signature. Natural jets, he argued, usually come from uneven heating of an irregular surface and point in unpredictable directions. He also noted the comet’s spin axis lies within about 7 degrees of the Sun’s direction.

Loeb himself says 3I/ATLAS is most likely natural, and he rates it a 4 on his own 10-point scale. Most astronomers go further. NASA concluded in November 2025 that it behaves like a comet with unusual chemistry, and Penn State’s Jason Wright has argued that oddities are to be expected from a comet born around another star. Radio searches have found no artificial signals.