FuturismMysterious Interstellar Object Showing Signs of “Non-Gravitational Acceleration”Victor Tangermann
Thu, November 6, 2025 at 10:06 AM EST
3 min read
Interstellar object 3I/ATLAS is showing signs of "non-gravitational acceleration" as it reached its perihelion.In early July, astronomers spotted a mysterious object, later dubbed 3I/ATLAS after it was confirmed to be the third-ever interstellar visitor cruising through our solar system.
Last week, the object, which is now generally believed to be a comet, reached its closest point to the Sun, or its perihelion, brightening up at an unexpected rate and turning “distinctly bluer.”
And it may be getting a major boost that’s unaccounted for by the Sun’s gravitational pull as well. As NASA’s Jet Propulsion Laboratory navigation engineer Davide Farnocchia detailed in a recently filed report, 3I/ATLAS is showing signs of “non-gravitational acceleration.”
While that may sound like an alien spacecraft is lighting up its afterburners, there’s a far more mundane and natural explanation.
As Harvard astronomer Avi Loeb laid out in a blog post last week, the acceleration is likely the result of 3I/ATLAS losing significant amounts of mass, forming an elongating plume of dust and gas. Put simply, as it expels this material at a greater rate, it’s being kicked in the opposite direction.
Loeb suggests the object could lose “about a tenth of its mass” in a matter of a single month.
During an NBC News interview on Monday, Loeb explained that the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile observed a “deviation by four arcseconds in right ascension from the expected path.”
“And that’s very significant statistically,” he said, calculating the boost corresponding to the “evaporation of about a sixth of the mass of the object,” which is a “significant fraction.”
“Such a massive mass loss should be detectable in the form of a large plume of gas surrounding 3I/ATLAS during the upcoming months of November and December 2025,” he wrote in his blog, referring to the time the object will reemerge from behind the Sun.
At that time, we should be able to observe a “cloud of gas that carries five billion tons [of material] or more,” he told NBC.
The astronomer also suggested in his blog that the “massive evaporation of 3I/ATLAS might explain its unusual brightening.”
However, Loeb still left the door open for a more far-fetched explanation for the rapid acceleration as well. The researcher has long suggested 3I/ATLAS could be an enormous alien spacecraft, pointing at numerous “anomalies” that make it a major outlier, even when compared to the other two interstellar objects we’ve observed so far.
“Alternatively, the non-gravitational acceleration might be the technological signature of an internal engine,” Loeb wrote in his blog. “This might also explain the report on 3I/ATLAS getting bluer than the Sun.”
Loeb explained that the object’s dust is “expected to redden the scattered sunlight,” which would result in it “having a redder color than the Sun.”
The blue color, on the other hand, “could potentially be explained by a hot engine or a source of artificial light,” Loeb posited.
Even then, the color change could once again have a natural explanation. Instead, it could simply “be a signature of ionized carbon monoxide for a natural comet,” Loeb conceded.
Besides, the little “non-gravitational acceleration” that 3I/ATLAS experienced won’t be enough to bring it “significantly closer to any Solar System planet from its original gravitational path.”
Unfortunately, Loeb’s efforts to study the object have been greatly complicated by the ongoing government shutdown, telling NBC that he still hadn’t “heard back” from interim NASA administrator Sean Duffy after inquiring about 3I/ATLAS observations by NASA’s Mars Reconnaissance Orbiter during its flyby of the planet last month.
“I think it’s inappropriate to withhold the scientific information from the community because we are planning future observations based on what we know about 3I/ATLAS,” he said during the interview. “We will continue to push for answers.”
https://www.yahoo.com/news/articles/mysterious-interstellar-object-showing-signs-150631147.html
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