Light from the Sun ... rays are not parallel. A periscope uses two mirrors to allow someone to look over an obstacle. Submarines use periscopes to see ships on the surface of the sea.

From oddly shaped clouds to rainbowlike colors in the sky, there are plenty of fascinating weather phenomena that can capture your attention, even when there's no storm in sight. Whether you're a ...

While sunsets on Mars are uniquely moody, NASA 's Curiosity rover has captured a stunning image of a martian sunset, featuring light rays that illuminated a bank of clouds as the sun set over the ...