### Question

How many astronomical units are in a light year?

Asked by:
Justin Dopiriak

### Answer

A good approximation would be:

1 light-year = 63240 AU (astronomical units)

Just for information, 1 light-year is equivalent to the distance travelled by light in 1 year moving in a vacuum. 1 light-year is about 9.4607 * 10^{15} metres.

1 astronomical unit (AU) is equivalent to the average radius of the Earth's orbit. 1 AU is about 1.4960 * 10^{11} metres.

Simple arithmetic calculation yields the answer that 1 light-year = 63240 AU to a good approximation.

Answered by:
Ryan Leong, Undergraduate, NUS, Singapore
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