There is a main theme that connects all days of the week – all named after gods. In addition, six of the seven days of the week are named after Germanic and Nordic gods.
Sunday is named after the Germanic sun goddess Sunna. Monday is named after the Germanic moon god Máni. Tuesday is named after the Nordic martial god Týr. Wednesday is named after the Germanic god and soul tender Woden. Thursday is named after the Norse god Thor. Finally, Friday is named after the Norse goddess of foresight and wisdom Frigg.
This leaves us Saturday as the only day of the week whose name can not be traced back to either Germanic or Nordic deities. It is the only day of the week that retains its Roman origin in English and is named after the Roman god Saturn. As it stands, Saturday is the "Saturn day", a much nobler name than we would have had if we kept the Old Norse name ̵