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Solar Cycle (calendar)
The solar cycle is a 28-year cycle of the Julian calendar, and 400-year cycle of the Gregorian calendar with respect to the week. It occurs because leap years occur every 4 years, typically observed by adding a day to the month of February, making it February 29th. 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 1800, 1900, 2100, 2200, 2300 and 2500, which are divisible by four but which are common 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 letters 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 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Alexandria. The calendar became the predominant calendar in the Roman Empire and subsequently most of the Western world for more than 1,600 years until 1582, when Pope Gregory XIII promulgated a minor modification to reduce the average length of the year from 365.25 days to 365.2425 days and thus corrected the Julian calendar's drift against the solar year. Worldwide adoption of this revised calendar, which became known as the Gregorian calendar, took place over the subsequent centuries, first in Catholic countries and subsequently in Protestant countries of the Western Christian world. The Julian calendar is still used in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Berbers. The Julian calenda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Calendar
A lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most commonly used calendar, the Gregorian calendar, is a solar calendar system that originally evolved out of a lunar calendar system. A purely lunar calendar is also distinguished from a lunisolar calendar, whose lunar months are brought into alignment with the solar year through some process of intercalation. The details of when months begin vary from calendar to calendar, with some using new, full, or crescent moons and others employing detailed calculations. Since each lunation is approximately days, (which gives a mean synodic month as 29.53059 days or 29 days 12 hours 44 minutes and 3 seconds) it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of 12 such lunations, a lunar year, is 354 days, 8 h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friday The 13th
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, 2015 had a Friday the 13th in February, March, and November; 2017 through 2020 had two Friday the 13ths each; 2016, 2021 and 2022 had just one occurrence of Friday the 13th each; 2023 and 2024 will have two Friday the 13ths each. Friday the 13th occurs in any month that begins on a Sunday. History Unluckiness of "13" According to folklore historian Donald Dossey, the unlucky nature of the number "13" originated with a Norse myth about 12 gods having a dinner party in Valhalla. The trickster god Loki, who was not invited, arrived as the 13th guest, and arranged for Höðr to shoot Balder with a mistletoe-tipped arrow. Dossey: "Balder died, and the whole Earth got dark. The whole Earth mourned. It was a bad, unlucky day." ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doomsday Rule
The Doomsday rule, Doomsday algorithm or Doomsday method 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. The algorithm for mental calculation was devised by John Conway in 1973, drawing inspiration from Lewis Carroll's perpetual calendar algorithm. It takes advantage of each year having a certain day of the week upon which certain easy-to-remember dates, called the ''doomsdays'', fall; for example, the last day of February, 4/4, 6/6, 8/8, 10/10, and 12/12 all occur on the same day of the week in any year. Applying the Doomsday algorithm involves three steps: Determination of the anchor day for the century, calculation of the anchor day for the year from the one for the century, and selection of the closest date out of those that always fall on the doomsday, e.g., 4/4 and 6/6, and count of the number of days ( modulo 7) between that date and the date in question ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkat Hachama
''Birkat Hachama'' (ברכת החמה, "Blessing of the Sun") 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. According to Judaism, the Sun has a 28-year solar cycle known as ''machzor gadol'' (מחזור גדול, "the great cycle"). A solar year is estimated as 365.25 days and the "Blessing of the Sun", being said at the beginning of this cycle, is thus recited every 10,227 (28 times 365.25) days. The last time that it was recited was on April 8, 2009 (14 ''Nisan'' 5769 on the Hebrew calendar.) From an astronomical point of view, there is nothing special to these dates; e.g. the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nile
The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the List of rivers by length, longest river in the world, though this has been contested by research suggesting that the Amazon River is slightly longer.Amazon Longer Than Nile River, Scientists Say Of the world's major rivers, the Nile is one of the smallest, as measured by annual flow in cubic metres of water. About long, its drainage basin covers eleven countries: the Democratic Republic of the Congo, Tanzania, Burundi, Rwanda, Uganda, Kenya, Ethiopia, Erit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sirius
Sirius is the list of brightest stars, brightest star in the night sky. Its name is derived from the Ancient Greek language, Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinisation of names, Latinized to Alpha Canis Majoris, and abbreviated Alpha CMa or α CMa. With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as Canopus, the next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A-type main-sequence star, A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit every 50 years. Sirius appears bright because of its intrinsic luminosity and its proximity to the Solar System. At a distance of , the Sirius system is one of Earth's List of nearest stars, nearest neighbours. Sirius is gradually moving closer to the Solar S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunday
Sunday is the day of the week between Saturday and Monday. In most Western countries, Sunday is a day of rest and a part of the weekend. It is often considered the first day of the week. For most observant adherents of Christianity, Sunday is generally observed as a day of worship and rest, recognising it as the ''Lord's Day'' and the day of Christ's resurrection; in the United States, Canada, Japan, the Philippines as well as in most of South America, Sunday is the first day of the week. According to the Hebrew calendar and traditional calendars (including Christian calendars) Sunday is the first day of the week; Quaker Christians call Sunday the "first day" in accordance with their testimony of simplicity. The International Organization for Standardization ISO 8601, which is based in Switzerland, calls Sunday the seventh day of the week. Etymology The name "Sunday", the day of the Sun, is derived from Hellenistic astrology, where the seven planets, known in English as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 differently so as to make the average calendar year 365.2425 days long, more closely approximating the 365.2422-day 'tropical' or 'solar' year that is determined by the Earth's revolution around the Sun. The rule for leap years is: There were two reasons to establish the Gregorian calendar. First, the Julian calendar assumed incorrectly that the average solar year is exactly 365.25 days long, an overestimate of a little under one day per century, and thus has a leap year every four years without exception. The Gregorian reform shortened the average (calendar) year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes.See Wikisource English translation of the (Latin) 1582 papal bull '' Inter gravissimas''. Second, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominical Letter
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 (or pair of letters for leap years) depending on which day of the week the year starts. Dominical letters are derived from the Roman practice of marking the repeating sequence of eight letters A–H (commencing with A on 1 January) on stone calendars to indicate each day's position in the eight-day market week (''nundinae''). The word is derived from the number nine due to their practice of inclusive counting. After the introduction of Christianity a similar sequence of seven letters A–G was added alongside, again commencing with 1 January. The dominical letter marks the Sundays. Nowadays they are used primarily as part of the computus, which is the method of calculating the date of Easter. A common year is assigned a single dominical letter, indicating which lettered days are Sundays in that particular year (hence th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Years
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 (like the earlier Julian 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. The common year of 365 days has 52 weeks and one day, hence a common year always begins and ends on the same day of the week (for example, January 1 fell on a Saturday and December 31 will fall on a Saturday in 2022, the current year) and the year following a common year will start on the subsequent day of the week. In common years, February has exactly four weeks, so March begins on the same day of the week. November also begins on this day. For example, February 2022 started on a Tuesday, so March started on a Tuesday as well. November follows the same characteristic. Each common year has 179 even-numbered days and 186 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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