Scientists are divided over whether the interstellar visitor 3I/ATLAS partly disintegrated at perihelion or whether the observed jets might have a less prosaic origin. Avi Loeb argues the object lost a large fraction of its mass — possibly fragmenting into about 16 pieces — and suggests engineered thrusters could explain some features with far less expelled material. Other researchers, including experts at Lowell Observatory and Penn State’s Jason Wright, contend the object appears consistent with a normal comet. Upcoming observations after solar conjunction will be decisive in distinguishing these possibilities.
Scientists Split Over Whether Interstellar Visitor 3I/ATLAS Blew Apart at Perihelion — Comet or Something Stranger?
Scientists are divided over whether the interstellar visitor 3I/ATLAS partly disintegrated at perihelion or whether the observed jets might have a less prosaic origin. Avi Loeb argues the object lost a large fraction of its mass — possibly fragmenting into about 16 pieces — and suggests engineered thrusters could explain some features with far less expelled material. Other researchers, including experts at Lowell Observatory and Penn State’s Jason Wright, contend the object appears consistent with a normal comet. Upcoming observations after solar conjunction will be decisive in distinguishing these possibilities.
10:23 AM, 11/13/2025Science
Scientists Split Over Whether Interstellar Visitor 3I/ATLAS Blew Apart at Perihelion
The debate about 3I/ATLAS, an interstellar object currently passing through the Solar System, has crystallized into two competing interpretations: a natural comet that partially disintegrated near the Sun, or a more exotic explanation such as engineered activity. Observations show unusual behavior, and researchers are now asking whether the object fragmented as it passed through perihelion — its closest approach to the Sun.
Avi Loeb's Case: Large Mass Loss or Engineered Jets
Avi Loeb, a Harvard astrophysicist who has been prominent in discussions of interstellar objects since 1I/ʻOumuamua in 2017, has highlighted measurements that he interprets as evidence of a very large mass loss during perihelion. Based on his estimates, the nucleus could have fragmented into roughly 16 pieces, producing the bright jets and debris now visible.
"This would mean that 3I/ATLAS exploded at perihelion and we are witnessing the resulting fireworks," Loeb has written, adding that if the object is natural, heating from the Sun could explain a dramatic reduction in mass.
Loeb also proposes an alternative: that the observed jets could be produced by technological thrusters rather than by expulsion of large amounts of cometary material. In this scenario, a much smaller fuel mass could generate similar-looking jets, reducing the required propellant by orders of magnitude compared with an ordinary comet.
Scientific Pushback and Caution
Other researchers caution that the evidence does not yet require exotic explanations. A scientist at Lowell Observatory described 3I/ATLAS to LiveScience as a "fairly ordinary, healthy-looking comet" with "no sign at all that the nucleus broke apart." Penn State astronomer Jason Wright, who has collaborated with Loeb in the past, was blunt in his critique, saying Loeb's claims are "demonstrably wrong" and arguing that cometary experts should be consulted where appropriate.
Critics emphasize an important distinction: all interstellar objects are, by definition, anomalous compared with native Solar System bodies, but the relevant question is whether 3I/ATLAS is anomalous enough to rule out a cometary origin.
Context and What Comes Next
Loeb has published analyses and non–peer-reviewed papers exploring the possibility of engineered origins and has openly debated other researchers, even pressing for the release of delayed images with the help of political allies. Those actions have amplified public attention but have not resolved the underlying scientific questions.
Ultimately, the debate should be settled by observations. As 3I/ATLAS emerges from solar conjunction, astronomers will look for an intact nucleus or evidence of substantial mass loss. If the nucleus is intact and the overall mass has not dropped dramatically, conventional cometary explanations will be favored; if the object is heavily fragmented, that will support the thermal-disruption scenario. Either outcome will provide valuable data about interstellar visitors.