1. The problem statement, all variables and given/known data By 2025 a spaceship shuttle service operates between the Earth and Mars. Each spaceship is equipped with identical mono chromatic head and tail lights, and their cruising speed v relative to earth, is such that the headlight of a homeward-bound spaceship appears green ( lambda = 500 nm) and the tail-light of a departing spaceship appears red(lambda = 600 nm).(i) What is v/c ?(ii) What is the wavelength of the headlight of an earth-b ound spaceship is observed froman outward b ound one? 2. Relevant equations http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/reldop2.html 3. The attempt at a solution I have no idea where to start.