Posted by: Sandy Steinman | September 13, 2018

How Far Is A Light-year?

EarthSky reports what a light year is and how far is it

Stars other than our sun are so far distant that astronomers speak of their distances not in terms of kilometers or miles – but in light-years. Light is the fastest-moving stuff in the universe. If we simply express light-years as miles and kilometers, we end up with impossibly huge numbers. But the 20th century astronomer Robert Burnham, Jr. – author of Burnham’s Celestial Handbook – devised an ingenious way to portray the distance of one light-year and ultimately of expressing the distance scale of the universe, in understandable terms.

He did this by relating the light-year to the astronomical unit – the Earth-sun distance.

One astronomical unit, or AU, equals about 93 million miles (150 million km).

Read full article at How far is a light-year? | Astronomy Essentials | EarthSky


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