The days of the week originated from ancient Roman and Germanic cultures, and were named after celestial bodies and ancient gods.
Here's the origin of each day's name:
1. *Sunday*: Named after the Sun (Latin: Dies Solis)
2. *Monday*: Named after the Moon (Latin: Dies Lunae)
3. *Tuesday*: Named after Tiw (Norse god of war and law), equivalent to Mars (Latin: Dies Martis)
4. *Wednesday*: Named after Woden (Norse god), equivalent to Mercury (Latin: Dies Mercurii)
5. *Thursday*: Named after Thor (Norse god of thunder), equivalent to Jupiter (Latin: Dies Iovis)
6. *Friday*: Named after Frigga (Norse goddess), equivalent to Venus (Latin: Dies Veneris)
7. *Saturday*: Named after Saturn (Latin: Dies Saturni)
The Roman names for the days of the week were adopted from the ancient Greeks, who in turn named them after the planets in their solar system.