Autokinesis

Autokinesis is a well-documented perceptual illusion in which a single, stationary point of light — a star, a distant streetlight, the planet Venus low on the horizon — appears to an observer staring fixedly at it in an otherwise dark or featureless field of view to drift, wander, or dart erratically, even though the light source itself has not moved at all. The effect arises from small, involuntary movements of the eye itself that the brain, lacking any other stationary reference point nearby to judge the light against, misattributes to the light moving rather than to the eye doing the moving — a well-established finding in visual-perception psychology entirely independent of UFO research, first studied systematically by psychologists in the early 20th century. Autokinesis is a leading documented cause of "erratic maneuvering light" UFO reports, particularly from witnesses who fixate on a single bright celestial object for an extended period, such as during a long night drive or a deliberate skywatching session — exactly the conditions most likely to produce sustained, undistracted staring at one point of light. The illusion compounds naturally with scintillation, since a twinkling, color-shifting star already looks unusual before autokinesis adds apparent movement on top of it.