Days of the week

Seven days of the week is the ISO 8601 standard used by most countries of the world. ISO is the International Standard Organization and has not approved a substitute to the Gregorian calendar currently used by the majority of the world. However, it provided the standard notations to record Gregorian dates, including one exempt from months. These notations are available in the technical ISO 8601 standard.

Why Seven Days in a Week?

It is Monday, the start of the week and you’re waiting for the weekend. Why do we have to wait six days until Sunday? You must be considering why Sunday is the last day and why Tuesday comes after Monday?

There are various opinions about the origin of the seven-day week. The most common view refers to Babylonian astrologers who allocated planet gods to weekdays around 700 BCE. The Romans then replaced these names with their gods of the planet in Germanics and ancient Roman calendar and the Nordics did the same thing with some of their gods.

There is one week for every moon phase. Similar to other calendars, Gregorian calendar ultimately depends on the moon phases. The moon takes approximately 29.5 days to turn through all phases of the moon. For daily use, this is a reasonably long and inconvenient period, so it makes sense to divide it into smaller slices.

Astronomers and astrologers developed a kind of constellation around 500 BC. C. Each day of the week was devoted to one of the classical planets: the seven unstable celestial bodies visible to the bare eye. These are; Sun, Moon, Mercury, Mars, Venus, Saturn and Jupiter. Some of the historical sources state that link between weekdays and the classical planets was established later by the ancient Greeks.

Let’s see the reasons behind the name of the days of the week.


It is first week day as per ISO 8601. However in Canada, Japan and the USA, it is second day of the week. It is an English word derived from Old English meaning moon day.


Tuesday comes after Monday and is the second day as per ISO 8601, although it is also counted as third day of the week in some cultures. This day of the week was named after Tyr, the Roman god of war.


Wednesday is the third day of the week according to ISO 8601, but some countries consider it the fourth day of the week.Wednesday is derived from Old English meaning Wodan day. The Germanic goddess Wodan is also known by the name of Odin, the father of the Nordic gods.


Thursday was named after Thor, the Norse god of thunder. Thursday means Thor’s day in Old English. Thor was filmed on a chariot pulled by the goats and using his hammer.


The English name for Friday is derived from Old English meaning day of Frigg, Norse goddess of love and fertility who is often considered the same goddess as Freya. Friday is the fifth day of the week according to ISO 8601 and the last working day of the week in most of the Western countries.


Saturday is the only day of the week where its Roman roots are preserved in English. It was named after Roman god and Saturn planet. Saturn is the Italic and Roman god of the consort of ops and agriculture.


The ISO 8601 Sunday is the seventh as well as the last day of the week. However, Sunday is the first day of the week in many countries, including Canada, Japan and the United States. The English word Sunday is derived from Old English meaning day of the sun.

We use the name of weekdays every day without realizing how much they tell us about our language and our history, and they work to show the connections between English and many other European languages. Knowing the reason behind seven days in a week and why these days are called as Sunday or Monday etc. will provide you with the required language.