One astronomical unit (AU) is defined as the average distance from the Earth to the Sun, which is approximately 149.6 million kilometers or about 93 million miles.
The time it takes for light to travel a distance of one AU can be calculated using the formula:
time = distance / speed of light
Using the speed of light as approximately 299,792 kilometers per second (or about 186,282 miles per second), we can determine the approximate time it takes for light to travel one AU:
time = 149,600,000 km / 299,792 km/s ≈ 499.0 seconds
So, light takes approximately 499 seconds, or roughly 8 minutes and 19 seconds, to travel a distance of one astronomical unit (AU) in a vacuum. This value is often referred to as the "light travel time" from the Sun to the Earth.