Why is the sky blue? – Mariana A-E., age 11, Tucson, Arizona. You might think that explaining why the sky is blue would be kind of simple. But even a brief explanation of it requires a lot of ...

On a clear, sunny day, the sky above us often glows a brilliant blue, a sight so commonplace that many of us rarely stop to question why. While this natural phenomenon might seem simple to explain ...

Saturn is where all the action is at this evening, as the planet’s brightest moon, Titan, slips beneath Saturn’s south pole. The planet rises around 9 P.M. local daylight time and stands more ...