NASA’s databases show that after perihelion, the comet not only sped up but also diverted slightly from its predicted path, forcing astronomers to refine their models. The agency describes the effect as a small but measurable non-gravitational acceleration—steady, persistent, and scientifically significant.
What Makes 31/ATLAS Different From Ordinary Comets
From the moment it was discovered, 31/ATLAS stood apart from familiar comets that originate in the Sun’s distant Oort Cloud. This object arrived on a hyperbolic trajectory, meaning it is not bound to the Sun’s gravity and will never return once it leaves the solar system.
As NASA explains in its 3I/ATLAS Facts and FAQs, the “3I” designation marks it as only the third known interstellar object ever detected passing through our neighborhood, following 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.
Unlike long-period comets, which follow looping elliptical paths, 31/ATLAS came from the broader Milky Way and is now heading back there—making every observation a once-in-a-lifetime opportunity.
NASA’s Leading Explanation: Solar-Driven Outgassing
Despite speculation swirling online, NASA researchers say the most likely explanation for the comet’s acceleration is well understood in principle: outgassing.
