Solar cycle (calendar)
Encyclopedia
The solar cycle is a 28-year cycle of the Julian calendar
with respect to the week
. It occurs because leap years
occur every 4 years and there are 7 possible days to start a leap year
, making a 28 year sequence.
This cycle also occurs in the Gregorian calendar
, but it is interrupted by years such as 1700, 1800, 1900 and 2100, which are divisible by four but which are not leap years. This interruption has the effect of skipping 16 years of the solar cycle between February 28 and March 1. Because the Gregorian cycle of 400 years has exactly 146,097 days, i.e. exactly 20,871 weeks, one can say that the Gregorian so-called solar cycle lasts 400 years.
Calendar years are usually marked by Dominical letter
s indicating the first Sunday
in a new year, thus the term solar cycle can also refer to a repeating sequence of Dominical letters.
Unless a year is not a leap year due to Gregorian exceptions, a sequence of calendars is reused every 28 years.
The name solar cycle comes from Sunday, the traditional first day of the week
.
Julian calendar
The Julian calendar began in 45 BC as a reform of the Roman calendar by Julius Caesar. It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year .The Julian calendar has a regular year of 365 days divided into 12 months...
with respect to the week
Week
A week is a time unit equal to seven days.The English word week continues an Old English wice, ultimately from a Common Germanic , from a root "turn, move, change"...
. It occurs because leap years
Leap Years
Leap Years is a 2001 drama television series that aired on the Showtime cable network. The show was created by Ron Cowen and Daniel Lipman, who had created the American version of the series Queer as Folk. It followed a group of friends in New York City...
occur every 4 years and there are 7 possible days to start a leap year
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal year...
, making a 28 year sequence.
This cycle also occurs in the Gregorian calendar
Gregorian calendar
The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
, but it is interrupted by years such as 1700, 1800, 1900 and 2100, which are divisible by four but which are not leap years. This interruption has the effect of skipping 16 years of the solar cycle between February 28 and March 1. Because the Gregorian cycle of 400 years has exactly 146,097 days, i.e. exactly 20,871 weeks, one can say that the Gregorian so-called solar cycle lasts 400 years.
Calendar years are usually marked by Dominical letter
Dominical letter
Dominical letters are letters A, B, C, D, E, F and G assigned to days in a cycle of seven with the letter A always set against 1 January as an aid for finding the day of the week of a given calendar date and in calculating Easter....
s indicating the first Sunday
Sunday
Sunday is the day of the week between Saturday and Monday. For most Christians, Sunday is observed as a day for worship of God and rest, due to the belief that it is Lord's Day, the day of Christ's resurrection....
in a new year, thus the term solar cycle can also refer to a repeating sequence of Dominical letters.
Unless a year is not a leap year due to Gregorian exceptions, a sequence of calendars is reused every 28 years.
The name solar cycle comes from Sunday, the traditional first day of the week
Week
A week is a time unit equal to seven days.The English word week continues an Old English wice, ultimately from a Common Germanic , from a root "turn, move, change"...
.