I see there is a report of cyclopropenylidene (C3H2) in the atmosphere of Titan, one of Saturn's moons: https://www.independent.co.uk/life-...n-moon-titan-cyclopropenylidene-b1451305.html This is related to the smallest "aromatic" ring compound, which is an ion called the cyclopropenium cation: Please Register or Log in to view the hidden image! which has 2 electrons in a ring-shaped conjugated system and thus has aromatic stability according to Hückel's rule, even though the σ-bond angle introduces a lot of strain. Cyclopropenylidene is the neutral molecule obtained by abstracting H+ from one carbon atom. This will be less stable than the C3H3+ cation. I'm not sure what real significance there is in finding these molecules on Titan, save that there is some unusual carbon chemistry going on. But it's nice to see that the theoretical minimum aromatic molecule does exist somewhere in nature. Please Register or Log in to view the hidden image!