A common year starting on Thursday is any non-
leap year
A leap year (also known as an intercalary year or bissextile year) is a calendar year that contains an additional day (or, in the case of a lunisolar calendar, a month) added to keep the calendar year synchronized with the astronomical year or ...
(i.e. a year with 365 days) that begins on
Thursday,
1 January
January 1 or 1 January is the first day of the year in the Gregorian Calendar. There are 364 days remaining until the end of the year (365 in leap years). This day is also known as New Year's Day since the day marks the beginning of the yea ...
, and ends on
Thursday,
31 December
It is known by a collection of names including: Saint Sylvester's Day, New Year's Eve or Old Years Day/Night, as the following day is New Year's Day. It is the last day of the year; the following day is January 1, the first day of the following ...
. Its
dominical letter hence is D. The most recent year of such kind was
2015 and the next one will be
2026 in the
Gregorian calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years d ...
or, likewise,
2021 and
2027 in the obsolete
Julian calendar
The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandri ...
, see
below for more.
This is the only common year with three occurrences of
Friday the 13th: those three in this common year
occur in February,
March, and
November.
Leap years starting on Sunday
A leap year starting on Sunday is any year with 366 days (i.e. it includes 29 February) that begins on Sunday, 1 January, and ends on Monday, 31 December. Its dominical letters hence are AG. The most recent year of such kind was 2012 and the next ...
share this characteristic, for the months January, April and July. From February until March in this type of year is also the shortest period (one month) that runs between two instances of
Friday the 13th.
In this common year, February is a unique rectangle calendar when weeks start on Sundays,
Martin Luther King Jr. Day is on
January 19
Events Pre-1600
* 379 – Emperor Gratian elevates Flavius Theodosius at Sirmium to ''Augustus'', and gives him authority over all the eastern provinces of the Roman Empire.
* 649 – Conquest of Kucha: The forces of Kucha surrender a ...
,
Valentine’s Day is on a
Saturday
Saturday is the day of the week between Friday and Sunday. No later than the 2nd century, the Romans named Saturday ("Saturn's Day") for the planet Saturn, which controlled the first hour of that day, according to Vettius Valens. The da ...
,
President's Day is on
February 16
Events Pre-1600
* 1249 – Andrew of Longjumeau is dispatched by Louis IX of France as his ambassador to meet with the Khagan of the Mongol Empire.
* 1270 – Grand Duchy of Lithuania defeats the Livonian Order in the Battle of K ...
,
Saint Patrick’s Day is on a
Tuesday,
Memorial Day is on its earliest possible date,
May 25,
U.S. Independence Day and
Halloween are on a Saturday,
Labor Day is on its latest possible date,
September 7,
Thanksgiving is on
November 26, and
Christmas
Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year ...
is on a
Friday
Friday is the day of the week between Thursday and Saturday. In countries that adopt the traditional "Sunday-first" convention, it is the sixth day of the week. In countries adopting the ISO-defined "Monday-first" convention, it is the fifth d ...
. This common year is also the only one where
Memorial Day and
Labor Day are not 14 weeks (98 days) apart: they are 15 weeks (105 days) apart in this common year.
Leap years starting on Wednesday share this characteristic.
Calendars
Applicable years
Gregorian Calendar
In the (currently used) Gregorian calendar, alongside
Tuesday, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-four common years per cycle or exactly 11% start on a Thursday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.
400 year cycle
century 1: 9, 15, 26, 37, 43, 54, 65, 71, 82, 93, 99
century 2: 105, 111, 122, 133, 139, 150, 161, 167, 178, 189, 195
century 3: 201, 207, 218, 229, 235, 246, 257, 263, 274, 285, 291
century 4: 303, 314, 325, 331, 342, 353, 359, 370, 381, 387, 398
Julian Calendar
In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a
28-year cycle (1461 weeks). A leap year has two adjoining dominical letters (one for January and February and the other for March to December, as 29 February has no letter). This sequence occurs exactly once within a cycle, and every common letter thrice.
As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 3, 14 and 20 of the cycle are common years beginning on Thursday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Thursday.
References
{{DEFAULTSORT:Common Year Starting On Thursday
Gregorian calendar
Julian calendar
Thursday