A light-year is a unit of distance typically used when expressing distances to stars and other objects on a galactic scale.

 

Quite simply, it is the distance that light travels in one year.

 

More specifically, it refers to the Julian year (365.25 days), and to the speed of light in a vacuum.

 

When you work it out, the distance is quite literally astronomical!

 

It is well over 9 trillion kilometres. A light-year is 9,460,730,472,581 kilometres to be exact.

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How far, on our model, would light travel in one year?

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We know from our earlier calculations that 1 km is represented by 0.00647 millimetres.

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So that translates to 61,211 km on our model.