I have posted about Saturn day before but here’s the full week. The origin is Sumerian and based on lunar cycles.
NAMED AFTER GODS AND PLANETS
The names of the 7 days of the week in most Latin-based languages come from the Roman calendar, which related each day with 7 celestial bodies considered to be gods: the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn.
The English language has retained the planet names for Saturday, Sunday, and Monday. However, the names for the other days of the week have been replaced by their equivalent Norse or Germanic gods.
Some Asiatic languages such as Hindi, Japanese, and Korean have a similar relationship between the weekdays and the planets.
SUNDAY: from Middle English sunnenday from Old English sunnandæg (“day of the sun”), from sunne (“sun”), + dæg (“day”), late Proto-Germanic *sunnōniz dagaz, as a translation of Latin dies Solis and of Greek ήμέρα Ἥλιου (heméra Helíou); declared the “venerable day of the sun” by Roman Emperor Constantine on March 7, 321 CE. Compare Dutch zondag, West Frisian snein, German Sonntag, Danish søndag.
SOL – (Roman mythology) ancient Roman god; personification of the sun; counterpart of Greek Hēlios (Greek mythology).
MONDAY from Old English mōnandæġ (“day of the moon”), from mōna (“moon”) + dæg (“day”), late Proto-Germanic *mēniniz dagaz, a translation of Latin dies Lunae and of Greek ήμέρα Σελήνης (heméra Selénes). Compare West Frisian moandei, Dutch maandag, German Montag, Danish mandag.
LUNA – (Roman mythology) the goddess of the Moon; counterpart of Greek Selḗnē (Greek mythology).
TUESDAY from Middle English Tewesday, from Old English Tīwesdæġ (“Tuesday”), from Proto-Germanic *Tīwas dagaz (“Tuesday”, literally “Tiw’s Day”), from *Tīwaz (“Tyr, god of war”) + *dagaz (“day”). This was a Germanic rendering of Latin dies Martis in interpretatio germanica, itself a translation of Ancient Greek ήμέρα ‘Άρεως (heméra Áreos “day of Ares”) (interpretatio romana). Cognate with Scots Tysday (“Tuesday”), West Frisian tiisdei (“Tuesday”), German dialectal Ziestag (“Tuesday”), Danish tirsdag (“Tuesday”), Swedish tisdag (“Tuesday”). More at Tyr, day.
TYR – (Norse mythology) god of war and strife and son of Odin; identified with Anglo-Saxon Tiu or Tiw.
From Old Norse Týr, from Proto-Germanic *Tīwaz, from Proto-Indo-European *dhyeu- (“god”). Cognate to Old English Tīw.
WEDNESDAY from Middle English Wednesdai, Wodnesdei, from Old English wōdnesdæġ (“Wednesday”), from a Germanic (compare Proto-Germanic *Wōdanas dagaz) calque of Latin dies (“day”) Mercurii (“of Mercurii”) and Koine Ancient Greek ἡμέρα (hemera, “day”) Ἕρμου (Hermou, “of Hermes”), via an association of the god Odin (Woden) with Mercury and Hermes.
ODIN – (Norse mythology and Heathenry) The supreme god of the Germanic and Norse pantheons, the leader of the Æsir, after whom Wednesday is named; the god of war and poetry, the husband of Frigg, the father of Balder, Hod, Hermod, Thor and Tyr. The Allfather, the One-eyed, the Terrible One, the Father of Battle.
Odin from Old Norse Óðinn, akin to Old High German Wotan and Old English Wōden. From Proto-Germanic *Wōdanaz, derived from Proto-Germanic *wōþuz (“rage, manic inspiration, furor poeticus”), from Proto-Indo-European *wet-. Compare Old Norse óðr and Dutch woede (rage) and woeden (to rage).
THURSDAY from Middle English, from Old English þursdæġ, þurresdæġ (“Thursday”), possibly from a contraction of Old English þunresdæġ (“Thursday”, literally “Thor’s day”), but more likely of North Germanic origin, from Old Norse þōrsdagr or Old Danish þūrsdag (“Thursday”); all from Proto-Germanic *Þunras dagaz (“Thor’s day”). Compare West Frisian tongersdei, Dutch donderdag, German Donnerstag, Danish torsdag. More at thunder, day.
A calque of Latin dies Iovis (dies Jovis) and of Ancient Greek ἡμέρα Ζεύς or ήμέρα Διός (heméra Zeús or heméra Diós, “day of Zeus”), via an association of the god Thor with the Roman god of thunder Jove (Jupiter) and with the Greek god of thunder Zeus.
THOR – (Norse mythology) god of thunder and rain, farming and son of Odin; pictured as wielding a hammer emblematic of the thunderbolt; identified with Teutonic Donar.
Representing Old Norse Þórr (Swedish Tor); cognate with Old English þunor.
FRIDAY from Old English frīġedæġ. Compound of frīġe and dæġ “day”, corresponding to late Proto-Germanic *Frijjōz dagaz (“day of Frigg”). Compare West Frisian freed, Dutch vrijdag, German Freitag, Danish fredag. Old Norse Frigg (genitive Friggjar), Old Saxon Fri, and Old English Frig are derived from Common Germanic Frijjō. Frigg is cognate with Sanskrit prīyā́ which means “wife.” The root also appears in Old Saxon fri which means “beloved lady”, in Swedish as fria (“to propose for marriage”) and in Icelandic as frjá which means “to love.”
A calque of Latin dies Veneris and of Ancient Greek ήμέρα Άφροδίτης (heméra Afrodítes), via an association of the goddess Frigg with the Roman goddess of love Venus and the Greek goddess of love Aphrodite.
FRIGG – (Germanic mythology, Norse mythology) The wife of Odin, and the Norse/Germanic goddess of married love, the heavens, home and hearth, after whom Friday is named (due to her being identified with Venus and Aphrodite).
From Old Norse Frigg, from Proto-Germanic *Frijjō.
SATURDAY from Old English Sæternesdæg (“day of Saturn”), from Sætern (“Saturn”), from Latin Saturnus and from Greek Κρόνου (kronos) (“the god of fertility, agriculture and vegetation”), possibly from Etruscan, + Old English dæg (“day”); a translation of Latin dies Saturni and of Greek ήμέρα Κρόνου (heméra Krónou “day of Kronos”) Compare West Frisian saterdei, Dutch zaterdag.
SATURN – (Roman mythology) The god of fertility, agriculture and vegetation; counterpart of Greek Kronos (Greek mythology).
From Old English Sætern, from Latin Saturnus, probably of Etruscan origin, plausibly influence by Latin satus, past participle of serere (“to sow”).
Ancient Greek Κρόνος, possibly from the Ancient Greek κραίνω (krainō, “to rule or command”).