An astronaut flies from the Earth to a distant star at 60% of the speed of light. As measured by the astronaut, the one-way trip takes 18 years.
a) How long does the trip take as measured by an observer on the Earth?
b) What is the distance from the Earth to the star (in light-years) as measured by an Earth observer?
c) What is the distance from the Earth to the star (in light-years) as measured by the astronaut?