A rocket passes Earth and travels to a star, 80 light-years away. The earth hand the star are in the same frame of reference and the rocket moves at 0.9c with respect to the earth and the star. How many years does it take light to go form the start to earth, according to someone at rest on earth? what is the speed of the rocket in units of light years/year? How many years does it take the rocket to reach this star, according to clocks on Earth?