The illustration has been done following the indications of Thomas Sandby, a founder of the Royal Academy, and his brother Paul, both of whom witnessed the event.
The sighting was recorded the following year in the Philosophical Transactions of the Royal Society (1784), who relates what witnesses observed:
"An oblong cloud moving more or less parallel to the horizon. Under this cloud could be seen a luminous object which soon became spherical, brilliantly lit, which came to a halt; this strange sphere seemed at first to be pale blue in colour but then its luminosity increased and soon it set off again towards the East. Then the object changed direction and moved parallel to the horizon before disappearing to the South-East; the light it gave out was prodigious; it lit us everything on the ground."
It should be noted that the description of this object (below) is consistent with the would have been described as a meteor of the time. That being said it does not take into account that the object, stopped, changed color or brightness and also changed direction.
Note: According the Science & Society Picture Library (UK), the illustration depicts ‘the meteor of 18 August, 1783.' The following is the caption for this illustration from their website:
Print showing members of the nobility (King George III?) observing a very bright shooting star called a bolide from the terraces of the royal palace of Windsor Castle. Titled 'The meteor of August 18, 1783...', the aquatint was produced by Thomas Sandby after a watercolour by Paul Sandby. The dazzlingly bright meteor was seen widely in surrounding areas of England and disintegrated into several parts.
Windsor Castle UFO Sighting 1783, Spherical Object With Luminous Light, UFO, Meteor, England
