Two identical twins, Minky and Som, conduct their own twin paradox. Minky stays at home on Earth, whilst Som travels to a nearby star, Fazer, which is 10 light-years away, at a speed of 0.9c. When Som reaches Fazer, she turns around and returns to the Earth, once again at a speed of 0.9c.
a. Calculate how much time Minky measures for Som to reach Fazer.
b. Calculate how much Som has aged in her reference frame of the moving spaceship.