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# What is the speed of light?

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The speed of light in a vacuum is a universal constant, with a value of 299,792,458 meters per second. Nothing in the universe that has mass can, even theoretically, exceed this speed.

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The speed of light is so fast that it has become a convenient standard for measuring the vast distances in the solar system and beyond it. The distance between the Earth and the Moon, for example, is slightly less than 1 light-second. Light from the Sun takes 8 minutes to reach the Earth, and it takes around 1 hour to pass by the orbits of Jupiter and Saturn.

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## Related Questions

• A:

The speed of light in a vacuum is measured at 186,282 miles per second, which is 670,616,629 miles per hour. The speed of light is denoted mathematically by the symbol "c."

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• A:

The speed of light in mph (miles per hour) is 6.702 x 108 mph or more precisely 670,616,629 mph. In metric units, the speed of light in a vacuum is 2.998 x 108 m/sec.

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• A:

The speed of light in water is approximately 225,000 km per second. While enormously fast, this is notably slower than the speed of light in a vacuum, which is 300,000 km per second.