This photo has been circulating the internet for the past week. If you stare at it long enough it will fade away (it'll take a minute). It happens because of something called the Troxler effect. It gets its name from Swiss physician Ignas Paul Vital Troxler.
In 1804, Troxler made the discovery that rigidly fixating one’s gaze on some element in the visual field can cause surrounding stationary images to seem to slowly disappear or fade