The Sun is 150 x 106 km away. If light travels at 3 x 108 m/s, how long does it take light from the Sun to reach the Earth?
distance = 150 x 106 km = 150 x 106 x 1000 m = 150 x 109 m
speed = 3 x 108 m/s
time = 500 s = 8.3 minutes
It takes 8.3 minutes for light to reach the Earth from the Sun.
A galaxy is observed to be 2.4x1020 m away from Earth?
1. 1 light year = 9.46 x 1015 m
The number of light years =
The number of light years = 25,370.
The galaxy is 25,370 light years away.
2. It would take 25,370 years for light to reach the earth from the galaxy.