1. The problem statement, all variables and given/known data Lets say that Planet A and Planet B are moving in the the same inertial reference frame. The distance between them is 8.3 light minutes. Event A occurs on Planet A at t=0, and Event B occurs on Planet B at t=2 minutes. If an observer is travelling from Planet A to B at 0.8c, what is the time difference between the two events? 2. Relevant equations 3. The attempt at a solution I want to say that we just need to use the Lorentz transformation, plugging in 2 minutes as the proper time, but it's probably not that simple.