There are 120 million rods which detect mainly black and white information, while there are up to seven million cones which identify different wavelengths of light roughly corresponding to red ...

From John Lennon with short hair to a young Christopher Walken on set, here are 50 rarely seen photos from the '60s and '70s.

A Chinese rocket fuel dump created a stunning white streak across the sky, leaving skywatchers in awe. See the photos here.