The Babylonians, who lived in modern-day Iraq, were astute observers and interpreters of the heavens, and it is largely thanks to them that our weeks are seven days long. The reason they adopted the number seven was that they observed seven celestial bodies — the Sun, the Moon, Mercury, Venus, Mars, Jupiter and Saturn.
For centuries the Romans used a period of eight days in civil practice, but in 321 CE Emperor Constantine established the seven-day week in the Roman calendar and designated Sunday as the first day of the week.
The modern seven-day week can be traced back to the Babylonians, who used it within their calendar. Other ancient cultures had different week lengths, including ten in Egypt and an eight-day week for Etruscans.
Who Named the Days of the Week? The Romans had observed the same seven celestial bodies as the Babylonians, and they decided to name the days of the week after the gods and goddesses associated with them. The Romans provided the Latin basis for the name of each day.
There's no good reason for it, and yet, it's constant to almost every single culture. Jews, who use a lunar calendar made up of either 12 or 13 months beginning with the New Moon, use a seven-day week. The Bengali calendar, which splits the year up into six seasons of two months each, uses a seven-day week.
The seven-day week was adopted from the Hellenistic system by the 4th century CE, although its source is unclear. It was again transmitted to China in the 8th century by Manichaeans via Kangju (a Central Asian kingdom near Samarkand), and is the most-used system in modern China.
Burma. In the Burmese version of Theravada Buddhism, the week has eight days. Wednesday is divided into Wednesday proper (midnight to noon) and Rahu (noon to midnight). Each day is associated with a compass direction, a planet, and a totem animal.
The English 'Saturday' originates from the Roman god Saturn, and can be recognized from Latin, where the day is called 'Dies Saturni'.
Tuesday was named for the Roman god of war, Mars, so in Latin was known as dies Martis. However, the Germanic god of war was known as Tiu and the English day of the week is derived from this Germanic god's name instead, first known as Tiwsday and eventually Tuesday.
The name Friday comes from the Old English frīġedæġ, meaning the "day of Frig", a result of an old convention associating the Nordic goddess Frigg with the Roman goddess Venus, with whom the day is associated in many different cultures.
The name for Sunday stems from the Middle English word sunnenday, which itself comes from the Old English word sunnandæg. The English derivations stem from the Latin diēs sōlis (“sun's day”). To know why this particular day is devoted to the sun, you have to look to Babylonian times.
The Islamic Calendar also has a seven-day week that is based on the story of creation. The major difference between that and the account in Genesis is that God started creation on Saturday and ended by creating humans just before the evening on Friday.
If there was an eighth day of the week, it would be called Funday.
Number of Weeks in a Month
All the months in the calendar have 4 complete weeks because every month has at least 28 days. A few months have some extra days, but they are not counted as a week because these extra days are not enough, to sum up to 7 days (1 week = 7 days).
The Gregorian calendar, currently used in most countries, is derived from the Hebrew calendar, where Sunday is considered the beginning of the week. Although in Judaism the Sabbath is on Saturday, while in Christianity it is on Sunday, Sunday is considered the beginning of the week in both religious traditions.
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.
Wednesday is named for the god Woden, who is paralleled with the Roman god Mercury, probably because both gods shared attributes of eloquence, the ability to travel, and the guardianship of the dead.
Monday likewise comes from Old English “Mōnandæg,” named after Máni, the Norse personification of the moon (and Sól's brother). Tuesday comes from Old English “Tīwesdæg,” after Tiw, or Tyr, a one-handed Norse god of dueling. He is equated with Mars, the Roman war god.
Sunday was another work day in the Roman Empire. On March 7, 321, however, Roman Emperor Constantine I issued a civil decree making Sunday a day of rest from labor, stating: All judges and city people and the craftsmen shall rest upon the venerable day of the sun.
While Jesus himself did not make a final break with the Sabbath, he so weakened it in the minds of his followers that they found it natural to move from worshipping on the Sabbath—a day of restrictions —to Sunday, a day associated with the joyous freedom brought about by the resurrection of Jesus.
Saturday (n.) seventh or last day of the week, Old English sæterdæg, sæternesdæg, literally "day of the planet Saturn," from Sæternes (genitive of Sætern; see Saturn) + Old English dæg (see day).
Between 2015 to 2019, Iceland conducted the world's largest pilot of a 35 to 36-hour workweek (cut down from the traditional 40 hours) without any calls for a commensurate cut in pay.
An Ethiopian year is comprised of 13 months, and is seven years behind the Gregorian calendar. In fact, Ethiopians celebrated the new millennium on September 11, 2007; this is because the Ethiopians continued with the same calendar that the Roman church amended in 525 AD.
According to international standard ISO 8601, Monday is the first day of the week. It is followed by Tuesday, Wednesday, Thursday, Friday, and Saturday. Sunday is the 7th and last day of the week.