Monday is the day of the week that takes place between Sunday and Tuesday. According to the International Organization for Standardization's ISO 8601 standard, it is the first day of the week.
Galileo's 1616 drawings of the Moon and its phases. Monday is named after the Moon in many languages.
A depiction of Máni, the personified moon, and his sister Sól, the personified sun, from Norse mythology (1895) by Lorenz Frølich
This postcard, sent in 1907 and captioned "Monday Morning in N. Y. City", reflects the tradition of Monday as a day for washing clothes.
Names of the days of the week
In many languages, the names given to the seven days of the week are derived from the names of the classical planets in Hellenistic astronomy, which were in turn named after contemporary deities, a system introduced by the Sumerians and later adopted by the Babylonians from whom the Roman Empire adopted the system during late antiquity. In some other languages, the days are named after corresponding deities of the regional culture, beginning either with Sunday or with Monday. The seven-day week was adopted in early Christianity from the Hebrew calendar, and gradually replaced the Roman internundinum.
Italian cameo bracelet representing the days of the week, corresponding to the planets as Roman gods: Diana as the Moon for Monday, Mars for Tuesday, Mercury for Wednesday, Jupiter for Thursday, Venus for Friday, Saturn for Saturday, and Apollo as the Sun for Sunday. Middle 19th century, Walters Art Museum