Star Distance
Astronomers calculate the distance to the furthest stars by comparing them to stars they know.
Why Is It?
24-Hour Colds
Why you sometimes feel a cold coming on, only to have the symptoms disappear the next day.
White Clouds
If water droplets are clear, why do the clouds that form from them appear white?
Microwaves
Some people think microwave ovens and cell phones are dangerous, but their fears are not backed up …
Pigeon Illusions
A listener asks: Why do pigeons bob their heads back and forth when they walk?
Tail-Wagging Birds
A listener asks: Why do some birds bob their tails up and down?