Add Yahoo as a preferred source to see more of our stories on Google. Last August Hinnerk Schulz-Hildebrandt noticed something strange while he was looking at a flight map on his phone. As his eye ...

Add Popular Science (opens in a new tab) More information Adding us as a Preferred Source in Google by using this link indicates that you would like to see more of our content in Google News results.

See this year's winning optical illusions and learn how they make the brain perceive things that are not reality.

Last August Hinnerk Schulz-Hildebrandt noticed something strange while he was looking at a flight map on his phone. As his eye traced the plane’s flight path, he noticed that the line looked purple, ...