Mount Etna, Europe’s largest volcano, puffs giant ‘smoke rings’ into sky

Mount Etna, Europe’s largest active volcano, puffed out a string of near-perfect rings over the weekend — prompting comparisons to smoke rings, or a fleet of giant flying saucers floating gently into the blue sky.

Etna formed the “volcanic vortex rings,” as they are known to scientists, through the rapid release of gas and vapors from a newly formed crater.