Speed of Light (c)
The speed of light is a unit of speed, used for theoretical physics, astronomy (light-years), and fiber optic communications. Its symbol is c.
c
km/h
1 speed of light equals
| Kilometers per Hour | 1,079,250,000 km/h |
| Miles per Hour | 670,617,000 mph |
| Meters per Second | 299,792,000 m/s |
About the speed of light
The speed of light in vacuum (c) was first measured by Ole Romer in 1676. It was fixed at exactly 299,792,458 m/s in 1983 as part of the SI definition of the meter.
In everyday use the speed of light appears in theoretical physics, astronomy (light-years), and fiber optic communications. As a point of reference: light from the Sun takes about 8 minutes and 20 seconds to reach Earth.