It is also been shown by Hsiao (1973) that moths are at first attracted towards the light, but as they approach the source, they actually then try to avoid its effects and end up flying around the lamp at a fixed distance (usually 20-30 cm) within a perceived dark area known as the Mach band
. Eventually, the insects either manage to escape from the lighted area or else settle down.
local time, we started to notice the thin, dark, hazy layer--the Mach band
or black-drop effect--between the limbs of Venus and the Sun.
Observational astronomy is rife with examples of these "Mach bands
," notably the "Terby White Spot," a spurious bright feature often seen bordering the intensely black shadow cast by Saturn's globe across the planet's rings (S&T: May 2014, p.
He also became interested in optical illusions, which led to his identification of what came to be called Mach bands
. The story is told in a conversational tone with occasional philosophical asides from the authors.
represent a special form of brightness contrast occurring at borders of adjacent visual stimuli differing in luminance (reviewed in Fiorentini, 1972).