When Mass used to be celebrated with the “priest’s back to the people,” everyone was in fact facing the east since the sun & the “Son” rise in the east. We symbolically look to the east for Christ to return again at the second coming.
In Pope Benedict’s encyclical, “Saved in Hope”, he speaks of how it became customary to have an image of Christ the King painted on the east wall of the church for this reason, and on the west wall of the church people would see a scene of the Last Judgment, the gospel for today on this feast of Christ the King. It was not meant to frighten them but to remind them as they left the church that they were called to serve Christ in the “corporal works of mercy” as they entered back into everyday life.
The pope said that artists tended to be more fascinated with the frightening aspects of this last judgement so would emphasize that in their work, but this is really a gospel of hope—the hope that we will see Christ every time we tend to their needs.