Joseph Wright of Derby (1734-1797)
“A Philosopher Lecturing on the Orrey”
Oil on canvas
Located in the Derby Museum and Art Gallery, Derby, England

An orrery is a mechanical model of the solar system that illustrates or predicts the relative positions and motions of the planets and moons.

Close observation of the adult faces in the picture reveals that each one of them demonstrates one of the main phases of the moon – new moon, half moon, gibbous moon and full moon.