This is not homework problem, but I am using a problem from Elementary Modern Physics by Weidner and Sells as context for my question. It reads "A star is moving away from the earth at 0.60c as measured in inertial system S, at rest with respect to the earth. At time t=0, when the star is 1.0 x 109 light years (ly) away, the two following events occur simultaneously as observed in S: (1) a bomb explodes nearby on earth; (2) a bomb explodes on the moving star. "Give the space and time coordinates for events 1 and 2 in S', at rest with respect to the star..." I know the mechanics of solving the problem correctly, but I wonder about the language. Does this mean that light from both explosions enters the eyes of the observer in S at the same instant? Or does it mean that the observer sees light of the explosion on Earth and then 1 billion years later sees light from the bomb on the star and calculates that the two explosion were simultaneous?