The speed of light in mph (miles per hour) is 6.702 x 108 mph or more precisely 670,616,629 mph. In metric units, the speed of light in a vacuum is 2.998 x 108 m/sec.
Theoretically, nothing can travel faster than light. The average distance from Earth to the Moon is 238,854 miles and light crosses that distance in about a second. The distance from the Sun to Earth is 92,955,817 miles and light only takes about 8 minutes to travel that distance.
Light travels in waves and can be slowed like sound, depending on the medium where it is traveling. Through the atmosphere of Earth, light moves almost as fast as it moves in a vacuum. The passing speed of light through a diamond is less than half of its vacuum speed.