The solar eclipse wasn't the only phenomenon to appear in the sky in recent days. CBS News reports on the weekend sight above Italy's Mount Etna, which produced what at times looked like perfectly circular volcanic vortex bubbles—some of which had a pink hue. A 2023 paper published in Scientific Reports noted the first observations of volcanic vortex rings at Italy's Etna and Vesuvius volcanoes date to 1724, and have since been sighted at volcanoes in Alaska, Ecuador, Iceland, Japan, and New Zealand, among other places.
But Etna's crater has a "perfect circled mouth," a member of the South Etna Alpine Guides Group tells Reuters, which he says contributes to the rings' almost perfectly circular nature. As for the science behind the phenomenon, the paper found "the formation of volcanic vortex rings requires a combination of fast gas release from gas bubbles (slugs) at the top of the magma conduit and regularity in the shape of the emitting vent."
The Washington Post adds the rings are made up of roughly 80% water vapor (which gives them their white coloring) and 20% sulfur dioxide and carbon dioxide. A Sicilian volcanologist says that no volcano produces as many volcanic vortex rings as Etna does, and that the quantities that were spewed most recently were "unprecedented." (More Mount Etna stories.)
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