Awasome Speed Of Light 2016 References. 6 mins read a a in vacuum, light always travels at a constant speed of 299,792,458 metres per second. This number was chosen to correspond to the most accurately measured value of the speed of light and is well within the experimental uncertainty.

Share to facebook share to twitter share to linkedin compared with intergalactic space, our galaxy is gravitationally dense. Web the speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; Speed of light = 299,792,458 m/s = 671,000,000 mph.