In 2021, dermatologist David Ozog was on holiday with his family in the Bahamas, when his 18-year-old son had a massive stroke. The teenager was airlifted to Florida, and then to Chicago for surgery.

The world is awash with the color purple — lavender flowers, amethyst gemstones, plums, eggplants and purple emperor butterflies. But if you look closely at the visible-light portion of the ...

The colors of the rainbow are all around us, but so are hues that most of us can't see, including ultraviolet — a wavelength that eludes many humans but, surprisingly, many animals can perceive.