How fast does light move in the air and in outer space?

Question

How fast does light move in the air and in outer space?

Answer 1

3 x 10^8 m

Answer 2

3*10^8 meters/second

Answer 3

"The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The ratio of the speed of light in the vacuum to the observed phase velocity is called the refractive index of the medium."

http://en.wikipedia.org/wiki/Speed_of_li...