optics

Some photos appear normal, except for an unearthly red color glowing from the pupils of your loved ones' eyes. Are Grandma and Uncle Felix possessed, or is there some other explanation for this red-eye phenomenon?

You're driving down the highway on a beautiful day as your child looks out the window. She asks, "Why is the sun following us?"

Why does the sunset take more time than the sunrise? It takes much less time for the sun to light up the sky at dawn than it does for all the light to disappear after the sun sets at dusk.

If you've ever had a bird feeder, you've probably noticed how much more colorful hummingbirds are compared to other birds. So how are hummingbirds so colorful, anyway? What makes their feathers so special?

Harvard neuroscientist Margaret Livingstone is pretty sure she's solved the puzzle of the Mona Lisa's changing smile. Presuming nothing, Livingstone reasoned that the famous portrait's flickering smile is caused by the way we see.

Have you ever wondered why fluorescent colors like the ones you see in highlighers or clothing dyes seem so much brighter than other colors? It's because they seem to reflect more light than they receive.

Things are not always as they seem, and this little demonstration will prove it. All you need is a cup of black coffee and an overhead light.