What is the speed of light?

The speed of light in a vacuum is approximately 299,792 kilometres per second (km/s) or about 186,282 miles per second. It is a fundamental constant of nature and is denoted by the symbol “c” in physics equations. Light’s speed decreases when it passes through materials like water or glass due to refraction. This constant plays a central role in Einstein’s theory of relativity, linking space and time. The speed of light sets the ultimate speed limit for the transfer of information and matter in the universe. It takes about 8 minutes and 20 seconds for sunlight to reach Earth, travelling at this speed.