Determination of the day of the week 10 months corresponds to the 2012 calendar year. On the other hand, 2019 is a common year starting on Tuesday, meaning that 2019 corresponds to the 2013 calendar year. 2020 is a leap year starting on Wednesday, meaning that 2020 corresponds to the 1992 calendar year, meaning that the first two months of the year begin on the same day as they do in 2014 (i.e. January 1 is a Wednesday and February 1 is a Saturday) but because of a leap day the last ten months correspond to the last ten months in 2015 (i.e. March 1 is a
Eight-day week popularity of the seven-day rhythm won and the eight-day week disappeared. The cycle of seven days, named after the sun, the moon, and the five planets visible to the naked eye, was already customary in the time of Justin Martyr, who wrote of the Christians meeting on the Day of the Sun (Sunday). Emperor Constantine eventually established the seven-day week in the Roman calendar in AD 321. The Celts used periods of darkness such as night and winter to begin their calculations of time. This meant that the first period of time in a "week" was a night, followed by