Question

Derive the value of 1 light year.

Answer 1

A light year is a distance travelled by light in one year in a vacuum.

Distance travelled by light in one year in vacuum = Velocity of light $\times$ 1 year (in seconds)

= 3 $\times$ ${10}^8$ $\times$ 365.25 $\times$ 24 $\times$ 60 $\times$ 60

= 9.467 $\times$ ${10}^{15}$ m

Therefore, 1 light year = 9.467 $\times$ ${10}^{15}$ m