This conforms wonderfully with every comet observed and it is a useful dust cloud. On the basis of the Pleistocene nonconformityin which a comet broke up and impacted our northern Ice Sheet, I do think that the dust is mostly elemental carbon.
We now also understand just how such an object can be targeted and carefully timed to essentially replicate the Pleistocene Nonconformity.
Understand that for twenty years I merely knew that the impossible had happened from the body of conforming evidence which certainly became possible from intelligent decissions and using not understood methods. We now undetrstand.
Twenty years to figure it out. Also Twenty years to figure out ho
w to build the Great Pyramid, on time and on budget. Also Twenty years to build the Great Pyramid.
3I/ATLAS is Hiding Behind a Veil of Dust
https://avi-loeb.medium.com/3i-atlas-is-hiding-behind-a-veil-of-dust-39e2d76468a9
Image of 3I/ATLAS on Dec. 21.627, 2025 UTC (with a contour plot on the left). The jet to the right (west) is the anti-tail heading towards the Sun. The field is 6 by 12 arcminutes, and the exposure duration is 15 seconds on the NEOSSat 0.15-m Maksutov orbiting telescope. The coordinate grid is ecliptic 2000. (Image credit: D. D. Balam (DAO/NRC), C. E. Spratt (ret), D. W. E. Green (CBAT), P. Langill (RAO/U. of Calgary), Omar Elmi (CSA), Jack Williams (CSA) & Canadian Space Agency)
In my latest two essays, accessible here and here, I showed that the characteristic radius of dust particles in the anti-tail jet launched from the interstellar object 3I/ATLAS is of order ~10 microns. This conclusion was based on the observed length of the jet and the requirement that the dust particles reach the jet speed through drag on the outflowing gas. Given these requirements, I derived here the mass density D of gas in the outflow at a distance d from the nucleus center,
D~(3.2*10^{-8} g/cm³)*(d/1km)^{-2},
Let us assume that a significant fraction of the total mass loss after perihelion is carried by ~10-micron dust particles. The mass of each 10-micron dust particle is m~10^{-8} g, implying that the particle number per unit volume near the base of the jet is:
n~D/m= 3.2 cm^{-3}*(d/1km)^{-2}.
The cross-sectional area of each 10-micron particle for scattering sunlight is:
S=pi*(10^{-3}cm)²= 3.14*10^{-6} cm².
Therefore, the scattering probability of sunlight from outside down to a distance d from the nucleus center is given by:
P = (n*S*d) ~ 1*(d/1km)^{-1}.
The minimum value of the radial distance d is the radius of the nucleus, R_n:
minimum{d}=R_n.
If the scattering probability P exceeds a value of unity, then the nucleus surface of a natural comet would not be exposed to sunlight and the release of gas or dust would stop. This implies that the radius of the nucleus for a natural comet must be larger than the value of d which yields P~1, namely:
R_n> 1 km,
corresponding to a minimum nucleus diameter for 3I/ATLAS of ~2 kilometers.
This lower limit applies only if the jet results from the illumination of the nucleus of a natural comet by sunlight. On the other hand, if the release of dust is intended to protect a technological object from sunlight, then a value of P>1 around the nucleus will be favored by design as a protective blanket. In this case, the nucleus of 3I/ATLAS might have a radius R_n<0.7 km which cannot be resolved in scattered sunlight by an external observer.
Either way, it is a remarkable coincidence that P is of order unity for the inferred size and mass loss rate of 3I/ATLAS. This coincidence could be a natural consequence of a self-regulating feedback loop that keeps the value of P close to ~1 because a larger value suppresses the release of dust whereas a smaller value enhances the release of dust, bringing the density of dust at the base of the jet to yield P~1. But it could also be a protective measure of an artificial origin.
In summary, the blanket of dust surrounding 3I/ATLAS is on the borderline between it being opaque and transparent to sunlight. This means that imaging by an external camera with a sub-kilometer spatial resolution would have likely shown a fuzzy cloud of dust rather than a nucleus with a sharp boundary.
3I/ATLAS is hiding behind a veil of dust.
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