An object that is travelling at the speed of light can go around the Earth seven and a half times in 1 second. In a vacuum, light can travel at speeds of 186,242 per second or 670,616,629 miles per hour. Albert Einstein put forward a theory that the speed of light is constant while other scientists theorize that the speed of light changes.
The speed of light has been theorized by early philosophers and scientists, such as Aristotle and Galileo. In 1975, it was known that the speed of light was 299,792,458 meters per second. At the speed of light, an object can travel from the Earth to the moon in 1.3 seconds, from the Earth to the sun in 8.3 minutes and from the sun to the nearest star in 4.2 years.