What Is the Speed of Light?

The speed of light in a vacuum is a universal constant, with a value of 299,792,458 meters per second. Nothing in the universe that has mass can, even theoretically, exceed this speed.

The speed of light is so fast that it has become a convenient standard for measuring the vast distances in the solar system and beyond it. The distance between the Earth and the Moon, for example, is slightly less than 1 light-second. Light from the Sun takes 8 minutes to reach the Earth, and it takes around 1 hour to pass by the orbits of Jupiter and Saturn.