'Red Sky at Night' and a Blue Sunset on Mars

You may know the old saying: 'Red sky at night, sailor's delight. Red sky in the morning, sailors take warning.'

In places where weather usually moves from west to east, like much of the United States, there is some truth in it.

A red sunset can mean clear, dry air to the west, where tomorrow's weather is coming from.

And if you ever watched a sunset on Mars, you would see something very different. NASA rovers have photographed Martian sunsets that glow blue, because of the way fine Martian dust scatters light.