Light - Calculate Distance per Time

Stopwatch and calculator for calculating the distance light travels in a medium in a given time. The speed of light is constant and is almost 300000 kilometers per second in a vacuum. The light therefore covers a very large distance in a short time. It takes a little over a second to get to the moon and about 8 minutes from the sun to us. The closest star to us after the Sun is Proxima Centauri in the Alpha Centauri star system, to which light already takes 4 1/4 years.

The calculator can also be used without the stopwatch, simply enter time or distance and press Calculate. To convert other time units into seconds, see Conversion of Time Units.

Example: in one fiftieth of a second, or 0.002 seconds, light travels 599.58 kilometers in a vacuum. In air under normal conditions, the speed of light is slightly less, namely 299705 kilometers per hour. In this time, light travels 599.41 kilometers, which is 17 centimeters less than in a vacuum.

The vacuum speed of light is a fundamental natural constant. The speed of light is the speed at which electromagnetic waves or photons move - always and exclusively. At the same time, it is the unattainable upper limit for the movement of matter, be it tiny single electrons or huge celestial bodies. Their speed is therefore always below the speed of light. This speed limitation can be explained by the relativistic mass growth. The faster something moves, the more mass this object has. This only becomes noticeable at very high speeds, which we do not encounter in everyday life. However, if an object with mass were to reach the speed of light, its mass would be infinitely large, which of course is not possible.

Physics commonly uses SI units. Here is a calculator to convert units.