27. The distance of a galaxy is of the order of 1025 m. Calculate the order of magnitude of time taken by light to reach us from the galaxy.

Hint: Speed=distancetime
Step 1: Find the order of the time.
Given, the distance of the galaxy =1025m
Speed of light =3×108m/s
Hence, the time taken by light to reach us from the galaxy is,
t = Distance  Speed =10253×10813×1017=103×1016=3.33×1016s