Computer modeling suggests an age exceeding 7.5 billion years, making it roughly three billion years older than the Sun and potentially the oldest comet ever observed.
Such antiquity may help explain some of its strange properties, but it does not fully account for the unusual particle sizes required to sustain the observed anti-tail glow.
Constraints on Particle Size and Jet Formation
According to Loeb’s analysis, the observed length of the anti-tail can only be maintained by particles with radii much larger than common dust grains. However, there is also a physical upper limit. If the particles were significantly larger, they would possess too little surface area per unit mass to be accelerated by gas to the high speeds required.
“The tight configuration of the anti-tail jet,” Loeb suggested, “might be the result of the release of large particles from a small fraction of the surface of the nucleus.” This suggests localized and possibly episodic activity on 31/ATLAS, rather than uniform outgassing.
From Color Changes to Artificial Light?
Adding to the intrigue, Loeb reported in September that 31/ATLAS had undergone “anomalous evolution,” including a noticeable color change. Earlier, in August, he suggested that the object might emit its own light “similar to car headlights,” a phenomenon for which no natural explanation has yet been confirmed.
