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 * 10¹⁵ metres.

1 astronomical unit (AU) is equivalent to the average radius of the Earth's orbit. 1 AU is about 1.4960 * 10¹¹ metres.

Simple arithmetic calculation yields the answer that 1 light-year = 63240 AU to a good approximation.
Answered by: Ryan Leong, Undergraduate, NUS, Singapore