Complex sentence: The constellation also contains an interesting galaxy cluster; the Perseus Cluster (Abell 426) is a massive galaxy cluster located 250 million light-years from Earth; at a redshift of 0.0179, it is the closest major cluster to Earth.
Split into simpler sentences: The constellation also contains an interesting galaxy cluster, the Perseus Cluster (Abell 426). It is a massive galaxy cluster located 250 million light-years from Earth; at a redshift of 0.0179, it is the closest major cluster to Earth.