The Solar System — Calculate

Calculate the time taken for light to travel from the Sun to the Earth, given the Sun-Earth distance is about 1.5 x 10^11 m.

Use time = distance / speed, i.e. t = d / c, where c = speed of light in a vacuum = 3 x 10^8 m/s. t = d / c = (1.5 x 10^11) / (3 x 10^8) = 500 s. Converting to minutes: 500 / 60 = 8.3 minutes (2 s.f.). So light takes about 500 s (8.3 minutes) to travel from the Sun to the Earth. The same equation, t = d/c, can be used to find the light travel time between any two Solar System objects if their separation distance is known.