The Sky of Arcs over St Petersburg
On a June morning in 1790, the sky over St Petersburg filled with rings, arcs and false suns, including some so rare they were named after the man who drew them.
What was reported
On 18 June 1790, the German-born chemist Tobias Lowitz, working in St Petersburg, watched an extraordinary display around the Sun. The sky was crossed by rings and arcs of light, with bright spots like extra suns on either side.
Lowitz carefully drew and described what he saw for the city's Academy of Sciences. Among the shapes were faint arcs curving down from the false suns, which were rarely seen again and are now called Lowitz arcs.
Explanations offered
Displays like this are caused by sunlight passing through ice crystals high in the atmosphere. Each shape of crystal, and the way it tumbles or floats, makes a different arc. Lowitz arcs come from a particular kind of crystal spinning as it falls, and their exact cause was argued about by scientists for centuries.
- When
- 18 June 1790
- Where
- St Petersburg, Russia
- Witnesses
- Tobias Lowitz and the people of St Petersburg
- 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.
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