3I/ATLAS has fascinated the academia and the armchair astronomy enthusiast on social media alike ever since the
interstellar comet’s discovery by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on July 01, 2025. Is it just
a billion-year-old exocomet with some bizarre features? Or is it a covert probe sent by our intergalactic neighbors?
That it ain’t traveling at the speed of light or forming warp waves, like in the sci-fi movies, is already a telltale
that probably (and hopefully) the 3I/ATLAS has no technological origin. However, it continues to baffle with its
anomalous behavior. 13 of which have been enlisted by Harvard astrophysicist Avi Loeb.
Continuing his study on the interstellar interloper 3I/ATLAS’s several anomalous features, Loeb has a new query. In his
new Medium blog entitled ‘Is the Sunward Anti-Tail of 3I/ATLAS Composed of a Swarm of Objects?’ the founder of the
If 3I/ATLAS is surrounded by a swarm of objects that do not share its non-gravitational acceleration, then these objects
will tend to be closer to the Sun relative to 3I/ATLAS, because 3I/ATLAS is pushed away from the Sun relative to the
objects through its non-gravitational acceleration.
If the objects started at the same velocity and position as 3I/ATLAS, then they would have a surplus in gravitational
binding energy by a fraction of Δ relative to 3I/ATLAS. However, they would have the same binding energy and track
3I/ATLAS if they have the same velocity and are displaced from its heliocentric distance by a fraction of Δ.
As long as the objects do not experience non-gravitational acceleration from mass loss as a result of the solar
illumination, they should maintain an anti-tail geometry—pointing always towards the Sun relative to 3I/ATLAS and
converging to its location at perihelion.
A large swarm of objects would have a much larger surface area than that of 3I/ATLAS, even if the total mass in them is
a small fraction of the mass of 3I/ATLAS. This swarm would create the appearance of a coma that reflects 99% of the
sunlight in the glow around 3I/ATLAS.
Towards the end, Loeb asks
If the anti-tail is indeed associated with a swarm of non-evaporating objects around 3I/ATLAS, the interesting question
is, what is the nature of these objects? Are they rocky fragments or something else?
Earlier in his blogs, Professor Loeb has speculated that 3I/ATLAS might be maneuvering towards Jupiter with the
intention of releasing probes. However, an event like this cannot go undetected, with NASA assets like JUNO observing
the interstellar object (ISO).
All eyes are on the sky, as the exocomet will fly by Earth, the closest ever, at 1.7 AU on December 19. It will soon be
crystal clear where there are swarms of objects tailing the 3I/ATLAS, with more scopes trained at the ISO.
See Also: 3I/ATLAS: Harvard Astrophysicist Avi Loeb’s List Of Dos & Don'ts If Exocomet Turns Out To Be Alien Space Probe
See Also: 3I/ATLAS: Observatory That First Spotted Exocomet Compares The 3 Interstellar Objects Ever To Enter Solar