A biomedical optics engineer discovered a visual illusion where purple dots appear bluer in peripheral vision. This ...

Smoke from Canadian wildfires is again blanketing parts of the U.S. in a thick haze. Midwestern cities like Chicago, Minneapolis, Detroit and Milwaukee posted some of the worst air quality in the ...

This week, millions of Americans are anxiously scanning air quality maps focusing on two colors: red and purple. Red indicates "unhealthy" air quality, and purple? "Very unhealthy." When did purple ...