Thursday named after Jupiter
Thor's day
The name is derived from Old English þunresdæg and Middle English Thuresday (with loss of -n-, first in northern dialects, from influence of Old Norse Þórsdagr) meaning "Thor's Day". It was named after the Norse god of Thunder, Thor. Thunor, Donar (German, Donnerstag) and Thor are derived from the name of the Germanic god of thunder, Thunraz, equivalent to Jupiter in the interpretatio romana.
In most Romance languages, the day is named after the Roman god Jupiter, who was the god of sky and thunder.  In Latin, the day was known as Iovis Dies, "Jupiter's Day".  In Latin, the genitive or possessive case of Jupiter was Iovis/Jovis and thus in most Romance languages it became the word for Thursday: Italian giovedì, Spanish jueves, French jeudi, Sardinian jòvia, Catalan dijous, Galician xoves and Romanian joi. This is also reflected in the p-Celtic Welsh dydd Iau.
The astrological and astronomical sign of the planet Jupiter (♃ ) is sometimes used to represent Thursday.
Since the Roman god Jupiter was identified with Thunor (Norse Thor in northern Europe), most Germanic languages name the day after this god: Torsdag in Danish, Norwegian, and Swedish, Hósdagur/Tórsdagur in Faroese, Donnerstag in German  or Donderdag in Dutch. Finnish and Northern Sami, both non-Germanic (Uralic) languages, uses the borrowing "Torstai" and "Duorastat". In the extinct Polabian Slavic language, it was perundan, Perun being the Slavic equivalent of Thor.
called after named for honored after called for