Because Sunday is the first day of the week.
I can answer you the same thing: why does your calendar start with Sunday? You start your week on Monday, right? You go to your job on Monday, not Sunday. So it doesn't make any sense that your week calendar starts on Sunday.
This year (2009) Advent begins on Sunday, November 29th.
I don't know... Maybe because Monday is the first day to the working week so the calendar begin by Monday.... Why is Saturday the last day in the English calendar?.. I have no idea about that...
Here in the US our calendar shows it to be the first day of the week.
5773 will begin on Sunday evening, September 16, 2012. Israel uses both the secular and the Hebrew calendar.
It corresponds with Sunday of the planetary week. Islamic days begin at sunset
From a perpetual US calendar: February 16, 2003 was on Sunday.
From a US perpetual calendar: August 9, 1942 was on Sunday.
The first Sunday in Advent.
The length of a regular year of the Gregorian calendar is 52 weeks and 1 day, and the length of a leap year is 52 weeks and 2 days. However, the number of whole calendar weeks (whole Sunday-to-Saturday weeks) in a year is usually 51. Only years that begin on Saturday or Sunday and leap years that begin on Friday include 52 whole calendar weeks.
The US standard of Sunday as the first day of the week is not observed in much of Europe, with Monday (lunes) often the first day of the calendar week.
The yearly calendar begins JANUARY 1 but the liturgical calendar begins on the first Sunday of Advent