Photoshop Elements 15 - register and size reduce four pictures to prepare mosaic

Post-sunset Crepuscular Rays
Twenty minutes after sunset on Tuesday there was a magnificent display of radiating post-sunset crepuscular rays with deep shadows. Light from the Sun below the horizon was being projected towards and reflected from a local layer of thin high level cloud and/or more widespread volcanic or forest fire derived stratospheric aerosols. The four images in this mosaic were taken a minute or two apart.