$A$ and $B$ are two stationary points on a line $30,000,000$ km apart.
A light flashes at $B$, and at that precise moment a rocket takes off at $A$ at $180,000$ km/second.
The rocket is considered stationary relative to itself, and thus Point $B$ is approaching the rocket at $180,000$ km/second. This reduces the distance from the rocket to $B$ by $0.8$ to $24,000,000$ km. The light travels at $300,000$ km/second, therefore the rocket will see the flash after $80$ seconds ($240,000,000/300,000$).
Is this calculation correct?
If it is not correct, could you please explain why.
Thank you very much!