Basel/Solothurn: Month-Long Spindle Observed From Two Observatories

On August 9, 1762, two independent observers at separate Swiss observatories reported a remarkable celestial phenomenon: a vast spindle-shaped object in slow flight across the disk of the sun, visible for nearly a month.

The Incident

Monsieur de Rostan, an astronomer and member of the Medicophysical Society of Basel, observed the object using a telescope.

Simultaneously, Monsieur Coste, observing from Sole near Basel with an eleven-foot telescope, reported the same phenomenon with identical characteristics.

The object remained visible for nearly a month, observable daily from Lausanne and other locations across the region.

Investigation

Rostan employed a camera obscura to delineate the figure of the object.

He transmitted this technical drawing to the Royal Academy of Sciences in Paris, representing one of the earliest instrumental attempts to document an aerial phenomenon scientifically.

Although the original drawing has not been preserved, contemporary records confirm its existence and the Academy's receipt of the documentation.

Significance

The observation occurred during a period of significant European intellectual development, when astronomical instruments and observational techniques were becoming increasingly sophisticated.

The involvement of trained astronomers using contemporary optical instruments—the telescope and camera obscura—distinguished this sighting from purely anecdotal reports.

The fact that multiple independent observers at different locations confirmed the same phenomenon strengthened the credibility of the account and suggested a genuine atmospheric or optical event rather than individual misperception.

Rostan's decision to create a technical drawing and submit it to the Royal Academy of Sciences demonstrates that the phenomenon was treated as worthy of serious scientific inquiry rather than dismissed as superstition.

The extended duration of visibility—approximately one month—and the consistency of observations across multiple locations and observers provide substantial corroborating evidence for the occurrence of an unusual atmospheric or optical phenomenon during this period.

This case represents one of the earliest scientifically documented aerial phenomena, distinguished by instrumental observation, independent corroboration, and formal submission to an academic institution, establishing a precedent for systematic investigation of unusual atmospheric events.