An interstellar object known as 3I/ATLAS has ignited significant discussion among astronomers due to its unexpected behavior as it passed behind the Sun. This peculiar movement appears to exhibit what some are calling “reverse thrust,” adding to a series of anomalies that have left scientists divided regarding the true nature of the object. 3I/ATLAS is only the third confirmed interstellar visitor detected, following the discoveries of “Oumuamua in 2017 and Borisov in 2019.
First identified on July 1, 3I/ATLAS has shown several unusual characteristics, including a shifting trajectory, unexpected brightness, and an unusual composition of gases. Harvard astrophysicist Avi Loeb has been vocal in proposing that 3I/ATLAS might not be a natural comet. He posits that if the object reemerges from behind the Sun in an unexpected location, it may indicate artificial propulsion, suggesting an engineered origin. “If 3I/ATLAS emerges somewhere gravity alone cannot explain, that would suggest an engineered object,” Loeb stated in an interview. He remarked that some scientists hesitate to explore this possibility due to concerns about their reputations.
Observations from the Two-Meter Twin Telescope in the Canary Islands detected a faint jet approximately 3.7 miles long directed toward the Sun. Additional investigations in August revealed nickel emissions without the usual presence of iron, a phenomenon not typically observed in standard comets. Researchers in Chile estimated that 3I/ATLAS is emitting around five grams of nickel and 20 grams of cyanide per second, with both emissions intensifying as the object approaches the Sun. Furthermore, a NASA analysis indicated a substantial release of carbon dioxide, estimated at approximately 940 trillion molecules per second, suggesting the object originated from a different type of solar system.
Despite its brightness, current assessments indicate that the comet is significantly smaller than initially thought. NASA has revised its size estimate from 12 miles to about 1.7 miles in diameter, noting that most of its visible light is produced by a thick coma—a surrounding cloud of dust and gas. Images captured by NASA”s Perseverance rover on Mars attracted attention for showing what seemed to be a cylindrical shape. However, Loeb believes this appearance may be distorted due to the rover”s camera processing multiple exposures over several minutes. He suggests the true form of the object is likely “smaller and rounder,” perhaps about 28 miles wide overall. Additionally, amateur astronomers have reported a greenish halo surrounding the object, a feature consistent with strong gas emissions.
Multiple research teams have concluded that the object”s unusual coloration, dust patterns, and an “anti-tail” (a tail that appears to point toward the Sun) can be explained by the viewing angles and sunlight reflection. Although there is no danger of collision, NASA has designated 3I/ATLAS as an object of interest for planetary defense, activating 227 observatories worldwide to monitor it. The object is expected to make its closest approach to Earth on December 19, and scientists anticipate gathering more data when it passes near NASA”s Juno spacecraft on March 16, 2026.
Loeb asserts that these recurring interstellar visitors—3I/ATLAS, “Oumuamua, and Borisov—serve as a stark reminder of the limited understanding we possess regarding objects beyond our solar system.
