Windsor Castle Observation: Royal Society Member Documents Aerial Phenomenon

On August 18, 1783, four witnesses on the terrace of Windsor Castle observed a luminous, oblong object gliding across the evening sky. This phenomenon was independently described by Tiberius Cavallo, a Fellow of the Royal Society, and published in the Philosophical Transactions of the Royal Society — one of the world's oldest and most prestigious scientific journals.

The Incident

Cavallo described the object as an 'oblong cloud moving more or less parallel to the horizon,' noting its unusual luminosity and steady, directed movement. The sighting occurred at 9:45 PM on the evening of August 18, 1783.

Key observations from the report:
- The object appeared as an oblong cloud initially
- A luminous sphere became visible beneath the cloud
- The sphere was pale blue in colour initially
- Its luminosity increased significantly over time
- The object changed direction and moved parallel to the horizon
- The light emitted was prodigious, illuminating everything on the ground
- The object eventually disappeared to the south-east

Witnesses and Documentation

Four witnesses observed the phenomenon from the terrace of Windsor Castle. The sighting was recorded the following year in the Philosophical Transactions of the Royal Society. The event was also captured in illustrations by Thomas Sandby (a founder of the Royal Academy) and his brother Paul, both of whom witnessed the event.

Significance

This represents one of the earliest aerial anomaly reports published in a peer-reviewed scientific publication. The documentation by a Royal Society Fellow in such a prestigious journal lends considerable credibility to the historical record of the observation.