Leap year starting on Monday

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A leap year starting on Monday is any year with 366 days (i.e. it includes 29 February) that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF, such as the years 1720, 1748, 1776, 1816, 1844, 1872, 1912, 1940, 1968, 1996, 2024, 2052, 2080, and 2120 in the Gregorian calendar [1] or, likewise, 2008, 2036, and 2064 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in September and December. Common years starting on Tuesday share this characteristic.

Monday day of the week

Monday is the day of the week between Sunday and Tuesday. According to the international standard ISO 8601 it is the first day of the week. In countries that adopt the "Sunday-first" convention, it is the second day of the week. The name of Monday is derived from Old English Mōnandæg and Middle English Monenday, originally a translation of Latin dies lunae "day of the Moon".

A leap year starting on Tuesday is any year with 366 days that begins on Tuesday, 1 January, and ends on Wednesday, 31 December. Its dominical letters hence are FE, such as the years 1884, 1924, 1952, 1980, 2008, 2036, 2064, 2092, and 2104 in the Gregorian calendar or, likewise, 1964, 1992, and 2020 in the obsolete Julian calendar. Any leap year that starts on Tuesday, Friday or Saturday has only one Friday the 13th; The only Friday the 13th in this leap year occurs in June. Common years starting on Wednesday share this characteristic.

Dominical letters or Sunday letters are a method used to determine the day of the week for particular dates. When using this method, each year is assigned a letter depending on which day of the week the year starts on.

Contents

Calendars

Calendar for any leap year starting on Monday,
presented as common in many English-speaking areas

010203040506
07080910111213
14151617181920
21222324252627
28293031 
 
010203
04050607080910
11121314151617
18192021222324
2526272829
 
0102
03040506070809
10111213141516
17181920212223
24252627282930
31 
010203040506
07080910111213
14151617181920
21222324252627
282930 
 
01020304
05060708091011
12131415161718
19202122232425
262728293031 
 
01
02030405060708
09101112131415
16171819202122
23242526272829
30 
010203040506
07080910111213
14151617181920
21222324252627
28293031 
 
010203
04050607080910
11121314151617
18192021222324
25262728293031
 
01020304050607
08091011121314
15161718192021
22232425262728
2930 
 
0102030405
06070809101112
13141516171819
20212223242526
2728293031 
 
0102
03040506070809
10111213141516
17181920212223
24252627282930
 
01020304050607
08091011121314
15161718192021
22232425262728
293031 
 

ISO 8601-conformant calendar with week numbers for
any leap year starting on Monday (dominical letter GF)

ISO 8601Data elements and interchange formats – Information interchange – Representation of dates and times is an international standard covering the exchange of date- and time-related data. It was issued by the International Organization for Standardization (ISO) and was first published in 1988. The purpose of this standard is to provide an unambiguous and well-defined method of representing dates and times, so as to avoid misinterpretation of numeric representations of dates and times, particularly when data are transferred between countries with different conventions for writing numeric dates and times.

The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.

01020304050607
08091011121314
15161718192021
22232425262728
293031 
 
01020304
05060708091011
12131415161718
19202122232425
26272829 
 
010203
04050607080910
11121314151617
18192021222324
25262728293031
 
01020304050607
08091011121314
15161718192021
22232425262728
2930 
 
0102030405
06070809101112
13141516171819
20212223242526
2728293031 
 
0102
03040506070809
10111213141516
17181920212223
24252627282930
 
01020304050607
08091011121314
15161718192021
22232425262728
293031 
 
01020304
05060708091011
12131415161718
19202122232425
262728293031 
 
01
02030405060708
09101112131415
16171819202122
23242526272829
30 
010203040506
07080910111213
14151617181920
21222324252627
28293031 
 
010203
04050607080910
11121314151617
18192021222324
252627282930
 
01
02030405060708
09101112131415
16171819202122
23242526272829
3031 

Applicable years

Gregorian Calendar

Leap years that begin on Monday, along with those that start on Saturday or Thursday, occur least frequently: 13 out of 97 (≈ 13.4%) total leap years of the Gregorian calendar. Their overall occurrence is thus 3.25% (13 out of 400).

A leap year starting on Saturday is any year with 366 days that begins on Saturday, 1 January, and ends on Sunday, 31 December. Its dominical letters hence are BA, such as the years 1820, 1848, 1876, 1916, 1944, 1972, 2000, 2028, 2056, 2084, 2124, 2152, and 2180 in the Gregorian calendar or, likewise, 2012 and 2040 in the obsolete Julian calendar. In the Gregorian calendar all centennial leap years start on Saturday; the next such year will be 2400, see below for more.

A leap year starting on Thursday is any year with 366 days that begins on Thursday 1 January, and ends on Friday 31 December. Its dominical letters hence are DC, such as the years 1880, 1920, 1948, 1976, 2004, 2032, 2060, and 2088, in the Gregorian calendar or, likewise, 1988, 2016, and 2044 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in February and August.

The Gregorian calendar is the calendar used in most of the world. It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make the average year 365.2425 days long, approximating the 365.2422-day tropical year that is determined by the Earth's revolution around the Sun. The rule for leap years is:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is.

Gregorian leap years starting on Monday [1]
Decade1st2nd3rd4th5th6th7th8th9th10th
17th century 1624 1652 1680
18th century 1720 1748 1776
19th century 1816 1844 1872
20th century 1912 1940 1968 1996
21st century 2024 2052 2080
22nd century 2120 2148 2176
23rd century 2216 2244 2272
24th century 2312 2340 2368 2396
25th century 2424 2452 2480
26th century 2520 2548 2576

Julian Calendar

Like all leap year types, the one starting with 1 January on a Monday occurs exactly once in a 28-year cycle in the Julian calendar, i.e. in 3.57% of years. 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).

Solar cycle periodic change in the Suns activity

The solar cycle or solar magnetic activity cycle is a nearly periodic 11-year change in the Sun's activity. Levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation, from active to quiet to active again, with a period of 11 years. This cycle has been observed for centuries by changes in the Sun's appearance and by terrestrial phenomena such as auroras.

Julian leap years starting on Monday
Decade1st2nd3rd4th5th6th7th8th9th10th
14th century 1308 1336 1364 1392
15th century 1420 1448 1476
16th century 1504 1532 1560 1588
17th century 1616 1644 1672 1700
18th century172817561784
19th century1812184018681896
20th century192419521980
21st century2008203620642092
22nd century212021482176

Related Research Articles

Friday the 13th Day in which the 13th of a month is on a Friday

Friday the 13th is considered an unlucky day in Western superstition. It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday, which happens at least once every year but can occur up to three times in the same year, for example in 2015, the 13th fell on a Friday in February, March, and November. In 2016, Friday the 13th occurred in May. In 2017, it occurred twice, in January and October. In 2018, it also occurred twice, in April and July. There will be two Friday the 13ths every year until 2020. The years 2021 and 2022 will have just one occurrence each.

A common year starting on Sunday is any non-leap year that begins on Sunday, 1 January, and ends on Sunday, 31 December. Its dominical letter hence is A. The most recent year of such kind was 2017 and the next one will be 2023 in the Gregorian calendar, or, likewise, 2018 and 2029 in the obsolete Julian calendar, see below for more. Any common year that starts on Sunday, Monday or Tuesday has two Friday the 13ths. This common year contains two Friday the 13ths in January and October.

A common year starting on Friday is any non-leap year that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2010 and the next one will be 2021 in the Gregorian calendar, or, likewise, 2011 and 2022 in the obsolete Julian calendar. The century year, 2100, will also be a common year starting on Friday in the Gregorian calendar. See below for more. Any common year that starts on Wednesday, Friday or Saturday has only one Friday the 13th; The only Friday the 13th in this common year occurs in August. Leap years starting on Thursday share this characteristic, but also have another one in February.

A common year starting on Monday is any non-leap year that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one will be 2029 in the Gregorian calendar, or likewise, 2013, 2019, and 2030 in the obsolete Julian calendar. The century year, 1900, was also a common year starting on Monday in the Gregorian calendar. See below for more. Any common year that starts on Sunday, Monday or Tuesday has two Friday the 13ths. This common year of this type contains two Friday the 13ths in April and July. Leap years starting on Sunday share this characteristic, but also have another in January.

A common year is a calendar year with 365 days, as distinguished from a leap year, which has 366. More generally, a common year is one without intercalation. The Gregorian calendar,, employs both common years and leap years to keep the calendar aligned with the tropical year, which does not contain an exact number of days.

A leap year starting on Sunday is any year with 366 days that begins on Sunday, 1 January, and ends on Monday, 31 December. Its dominical letters hence are AG, such as the years 1888, 1928, 1956, 1984, 2012, 2040, 2068, 2096, 2108, 2136, 2164, and 2192 in the Gregorian calendar or, likewise, 1996 and 2024 in the obsolete Julian calendar.

A common year starting on Tuesday is any non-leap year that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The current year, 2019, is a common year starting on Tuesday in the Gregorian calendar. The last such year was 2013 and the next such year will be 2030, or, likewise, 2014 and 2025 in the obsolete Julian calendar, see below for more. Any common year that starts on Sunday, Monday or Tuesday has two Friday the 13ths. This common year contains two Friday the 13ths in September and December. Leap years starting on Monday share this characteristic. From July of the year that precedes this year until September in this type of year is the longest period that occurs without a Friday the 13th. Leap years starting on Saturday share this characteristic, from August of the common year that precedes it to October in that type of year.

A common year starting on Wednesday is any non-leap year that begins on Wednesday, 1 January, and ends on Wednesday, 31 December. Its dominical letter hence is E. The most recent year of such kind was 2014, and the next one will be 2025 in the Gregorian calendar or, likewise, 2009, 2015, and 2026 in the obsolete Julian calendar. The century year, 1800, was also a common year starting on Wednesday in the Gregorian calendar, see below for more. Any common year that starts on Wednesday, Friday or Saturday has only one Friday the 13th; The only Friday the 13th in this common year occurs in June. Leap years starting on Tuesday share this characteristic.

A common year starting on Saturday is any non-leap year that begins on Saturday, 1 January, and ends on Saturday, 31 December. Its dominical letter hence is B. Examples include 1949, 1955, 1966, 1977, 1983, 1994, 2005, 2011 and 2022 in the Gregorian calendar or, likewise, 2017 and 2023 in the obsolete Julian calendar, see below for more. Any common year that starts on Wednesday, Friday or Saturday has only one Friday the 13th; The only Friday the 13th in this common year occurs in May. Leap years starting on Friday share this characteristic.

A common year starting on Thursday is any non-leap year that begins on Thursday, 1 January, and ends on Thursday, 31 December. 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 or, likewise, 2010 and 2021 in the obsolete Julian calendar, see below for more. This common year contains the most Friday the 13ths; specifically, the months of February, March, and November. Leap years starting on Sunday share this characteristic. From February until March in this type of year is also the shortest period that occurs within a Friday the 13th.

A leap year starting on Friday is any year with 366 days that begins on Friday 1 January and ends on Saturday 31 December. Its dominical letters hence are CB, such as the years 1808, 1836, 1864, 1892, 1904, 1932, 1960, 1988, 2016, 2044, 2072, 2112, 2140, 2168 and 2196 in the Gregorian calendar or, likewise, 2000 and 2028 in the obsolete Julian calendar. Any leap year that starts on Tuesday, Friday or Saturday has only one Friday the 13th; The only Friday the 13th in this leap year occurs in May. Common years starting on Saturday share this characteristic.

A leap year starting on Wednesday is any year with 366 days that begins on Wednesday, 1 January, and ends on Thursday, 31 December. Its dominical letters hence are ED, such as the years 1908, 1936, 1964, 1992, 2020, 2048, 2076, and 2116 in the Gregorian calendar or, likewise, 2004 and 2032 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in March and November. Common years starting on Thursday share this characteristic, but also have another in February.

The determination of the day of the week for any date may be performed with a variety of algorithms. In addition, perpetual calendars require no calculation by the user, and are essentially lookup tables. A typical application is to calculate the day of the week on which someone was born or a specific event occurred.

Doomsday rule Way of calculating the day of the week of a given date

The Doomsday rule is an algorithm of determination of the day of the week for a given date. It provides a perpetual calendar because the Gregorian calendar moves in cycles of 400 years.

Birkat Hachama Jewish blessing, thanking God for creating the sun, recited when the sun

Birkat Hachama refers to a rare Jewish blessing that is recited to the Creator, thanking Him for creating the sun. The blessing is recited when the sun completes its cycle every 28 years on a Tuesday at sundown. Jewish tradition says that when the Sun completes this cycle, it has returned to its position when the world was created. Because the blessing needs to be said when the sun is visible, the blessing is postponed to the following day, on Wednesday morning.

References

  1. 1 2 3 Robert van Gent (2017). "The Mathematics of the ISO 8601 Calendar". Utrecht University, Department of Mathematics. Retrieved 20 July 2017.