A particle of mass m and energy E falls from the Earth's zenith along the Z axis in the rest reference frame of a certain observer K. Another observer, K', moves with speed v along the positive X axis of K and observes the particle approaching him with an angle 0 with respect to the Z' axis. a) Calculate the angle 0 expressed in terms of the velocity u of the particle and the velocity v of K' b) Based on the result obtained in part a), give a description of what the starry sky would look like for a space cruiser moving at high speeds in our galaxy.

A particle of mass m and energy E falls from the Earth's zenith along the Z axis in the rest reference frame of a certain observer K. Another observer, K', moves with speed v along the positive X axis of K and observes the particle approaching him with an angle 0 with respect to the Z' axis. a) Calculate the angle 0 expressed in terms of the velocity u of the particle and the velocity v of K' b) Based on the result obtained in part a), give a description of what the starry sky would look like for a space cruiser moving at high speeds in our galaxy.