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What is a Light Year?

The meaning of a Light Year is misinterpreted a lot because people associate time with the "Year" part of Light Year.

A Light Year is actually a unit of measurement, specifically for distance. The description defined by the International Astronomical Union is "The distance that light travels in a vacuum in one Julian year (365.25 days)".

But what kind of distance is that?! Let's briefly look at the speed of light first...

In approximate terms, light travels at 300,000km or 186,000 miles per second (just in round numbers). Now that's pretty quick! Here are some examples of the speed of light...

Earth to Moon - 1.28 light seconds

Earth to Sun - 8.5 light minutes

Earth to Neptune - 4 light hours

Earth to Proxima Centauri - 4.3 light years

Earth to Andromeda Galaxy - 2.5 Million light years

And what is the distance of a light year? 9.461 trillion kilometres or 5.878625 trillion miles.

Next time you are out stargazing, this blog may put the vastness of space into perspective - Happy gazing!


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