Speed of Light in MPH

by Fraser Cain on August 22, 2009

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Lightspeed!

Lightspeed!


The speed of light in mph (miles per hour) is 670,616,629 mph.

Just to give you some perspective, the average distance from the Earth to the Moon is 238,854 miles. So light crosses that distance in about a second.

The average distance from the Sun to the Earth is 92,955,817 miles. Light only takes about 8 minutes to make that journey.

In fact, in just a single hour, light can get from the Sun all the way out to beyond the orbit of Jupiter and most of the way to Saturn.

Of course, most measurements of the speed of light are done in the metric system. Light moves 299,792,458 meters per second, or 1.02 billion km/hour.

We have written many articles about the speed of light for Universe Today. Here’s an article about how gravity is thought to move at the speed of light. And how gamma rays can move more slowly than light speed.

Here’s a cool calculator that lets you convert many different units for the speed of light, and here’s a relativity calculator, in case you wanted to travel nearly the speed of light.

We have recorded an episode of Astronomy Cast which answers many questions about the speed of light and relativity.

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

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