Free Astronomy Magazine November-December 2026

ASTRO PUBLISHING sing from localized regions of the surface and the Yarkovsky effect, arising from the thermal inertia of the rotating body; both forces cause an asymmetric effective thrust). The real discriminator between a natural and an artificial object is the anomalous spectrum, especially if it were to display lines attributa- I maginative examples of alien arti- facts “present” on the lunar sur- face: a spaceship half-submerged in debris and regolith, and a probe camouflaged among the rocks. The resolution of the images captured so far by lunar orbiters does not allow us to rule out the presence of this type of object. Rationality, perhaps, does. [AI artworks] simply be passing through our pres- ent. It would not be a novelty to discover that something can travel from one planetary system to an- other; this is amply demonstrated by the three interstellar cometary objects discovered so far, 1I/ ʻ Ou- muamua, 2I/Borisov, and 3I/ATLAS, which came from who knows where. Characterizing them has not been easy, so much so that there has been a lot of speculation about the nature of 1I/ ʻ Oumuamua to then conclude that it is a dark comet. An artifact originating from an- other system in the galaxy is ex- pected to display an anomalous trajectory or orbit, an anomalous shape, and an anomalous spectrum. The first two requirements are not conclusive, as amply demonstrated by 1I/ ʻ Oumuamua, which, in addi- tion to having a cigar shape, was also affected by non-gravitational forces (essentially, volatile outgas-