The Smoke Rings of Mount Etna
Europe's tallest active volcano sometimes blows perfect white rings of steam into the sky, hundreds of metres across, which drift slowly away.
What was reported
Mount Etna, in Sicily, is one of the most active volcanoes in the world. At times, one of its craters puffs out perfect rings of white vapour, which rise into the sky and spin slowly as they drift, sometimes lasting for several minutes. Some have been estimated at 200 metres across.
Photos of the rings, taken in 2000 and 2013, among other years, have been shared widely, and some people have taken them for strange objects or signs.
Explanations offered
The rings are vortex rings, the same as smoke rings. They form when gas is pushed quickly out of a narrow, roughly circular vent: the edges are slowed by friction, so the gas curls into a spinning doughnut. Etna produces them more than most volcanoes, though no one knows exactly why.
- When
- Seen in 2000, 2013 and since
- Where
- Mount Etna, Sicily, Italy
- Witnesses
- Volcanologists and visitors
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
More from Italy