Concept
Week
Related concepts (20)
Calendar reform
Calendar reform or calendrical reform is any significant revision of a calendar system. The term sometimes is used instead for a proposal to switch to a different calendar design. The prime objective of a calendar is to unambiguously identify any day in past, present and future by a specific date in order to record or organize social, religious, commercial or administrative events. Recurring periods that contain multiple days, such as weeks, months, and years, are secondary, convenient features of a calendar.
Tuesday
Tuesday is the day of the week between Monday and Wednesday. According to international standard ISO 8601, Monday is the first day of the week; thus, Tuesday is the second day of the week. According to some commonly used calendars, however, especially in the United States, Sunday is the first day of the week, so Tuesday is the third day of the week. In Muslim countries, Saturday is the first day of the week and thus Tuesday is the fourth day of the week.
Saturday
Saturday is the day of the week between Friday and Sunday. No later than the 2nd century, the Romans named Saturday diēs Sāturnī ("Saturn's Day") for the planet Saturn, which controlled the first hour of that day, according to Vettius Valens. The day's name was introduced into West Germanic languages and is recorded in the Low German languages such as Middle Low German satersdach, saterdach, Middle Dutch saterdag (Modern Dutch zaterdag) and Old English Sæternesdæġ, Sæterndæġ or Sæterdæġ.
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.
Mesoamerican calendars
The calendrical systems devised and used by the pre-Columbian cultures of Mesoamerica, primarily a 260-day year, were used in religious observances and social rituals, such as divination. These calendars have been dated to early as ca. 1100 BCE. By 500 BCE at the latest, the essentials were fully defined and functional. 260-day calendars are still used in the Guatemalan highlands, Veracruz, Oaxaca and Chiapas, Mexico.
February
February is the second month of the year in the Julian and Gregorian calendars. The month has 28 days in common years or 29 in leap years, with the 29th day being called the leap day. It is the first of five months not to have 31 days (the other four being April, June, September, and November) and the only one to have fewer than 30 days. February is the third and last month of meteorological winter in the Northern Hemisphere.
Universal Time
Universal Time (UT or UT1) is a time standard based on Earth's rotation. While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle (ERA, which serves as a modern replacement for Greenwich Mean Sidereal Time). UT1 is the same everywhere on Earth. UT1 is required to follow the relationship ERA = 2π(0.
Navagraha
The navagraha are nine heavenly bodies and deities that influence human life on Earth according to Hinduism and Hindu astrology. The term is derived from nava (नव "nine") and graha (ग्रह "planet, seizing, laying hold of, holding"). The nine parts of the navagraha are the Sun, Moon, planets Mercury, Venus, Mars, Jupiter and Saturn, and the two nodes of the Moon. The term planet was applied originally only to the five planets known (i.e., visible to the naked eye) and excluded the Earth.
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 day of the week. In most Western countries, Friday is the fifth and final day of the working week. In some other countries, Friday is the first day of the weekend, with Saturday the second. In Israel, Friday is the sixth day of the week.
Unit of time
A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as about 9 billion oscillations of the caesium atom. The exact modern SI definition is "[The second] is defined by taking the fixed numerical value of the cesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s−1.