A spacecraft travels along a straight line from Earth to the Moon, a distance of $3.84 \cdot 10^{8} \mathrm{~m}$. Its speed measured on Earth is $0.50 c$
a) How long does the trip take, according to a clock on Earth?
b) How long does the trip take, according to a clock on the spacecraft?
c) Determine the distance between Earth and the Moon if it were measured by a person on the spacecraft.