How Fast Is Light

186,282 miles per second, Light moves at 671 million miles per hour, 16.1 billion miles per day and 5.89 trillion miles per year; That is exactly how fast light is. Light is the fastest thing in the universe and because of that we use it's max speed over one year as a benchmark for very long distances. Everyones perspective of “light speed” is basically the same, as fast as possible, but how fast is “light speed”, really? Some examples may surprise you:

• Light from the Sun takes 8 minutes and 17 seconds to reach us, but inside the sun the energy takes millions of years to go from the center to the surface.

• It takes about 1.3 seconds for light or radio waves to reach us from the Moon, which really isn't all that far away (it's only 20 times farther away than Australia is to the United States). During the Apollo mission NASA had to wait about three seconds to hear the answer to every question they asked the astronauts. When the ship was on the opposite side of the moon that time would nearly double because the satellites available to send messages off of were at their greatest distances. The message had to be sent roughly twice the distance back to NASA.

• When Mars is closest to the Earth, it takes light three minutes to travel between the two planets. If you asked a question to an astronaut on Mars, you'd have to wait at least six minutes for an answer, and Mars is usually a lot farther away than that. At its greatest distance, you'd have to wait 42 minutes.

• Light takes four and a half years to travel to the nearest star (excluding the sun).It also takes light 100,000 years to travel across the width of our Milky Way Galaxy and 100 billion years to travel across the observable Universe, as it stands today.
  
  
  
  

When you think about the speed of light compared to the size of the known universe it becomes extremely less impressive. What stands out is how large the known universe is. Trying to comprehend how large that is almost gives you a headache. If the speed of light is the maximum speed that anything can travel at it would be impossible to explore the entire universe because it is always expanding.