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The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each. [1]

55 relations: Acceleration, Al-Biruni, Atomic clock, British Science Association, Caesium, Carl Friedrich Gauss, Centimetre–gram–second system of units, Civil time, Coordinated Universal Time, Day, Ephemeris time, Epoch (astronomy), Escapement, Frequency, Full moon, Gravitational time dilation, Heart, Hour, Hyperfine structure, International Astronomical Union, International Bureau of Weights and Measures, International System of Units, Isotopes of caesium, January 0, Jost Bürgi, Julian year (astronomy), Leap second, Metric prefix, Metric time, Minute, MKS system of units, New moon, Newcomb's Tables of the Sun, Orders of magnitude (time), Orpheus, Persian people, Revolution in Time, Roger Bacon, Sexagesimal, SI base unit, Sidereal year, Strontium, Sundial, System of measurement, Taqi ad-Din Muhammad ibn Ma'ruf, Time, Time standard, Tropical year, Tycho Brahe, United States Naval Observatory, ..., Universal Time, University of Pennsylvania Press, Velocity, Watch, William IV, Landgrave of Hesse-Kassel. Expand index (5 more) »

Acceleration

In physics, acceleration is the rate of change of velocity of an object with respect to time.

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Al-Biruni

Abū Rayḥān Muḥammad ibn Aḥmad Al-Bīrūnī (Chorasmian/ابوریحان بیرونی Abū Rayḥān Bērōnī; New Persian: Abū Rayḥān Bīrūnī) (973–1050), known as Al-Biruni (البيروني) in English, was an IranianD.J. Boilot, "Al-Biruni (Beruni), Abu'l Rayhan Muhammad b. Ahmad", in Encyclopaedia of Islam (Leiden), New Ed., vol.1:1236–1238.

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Atomic clock

An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.

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British Science Association

The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science.

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Caesium

Caesium (British spelling and IUPAC spelling) or cesium (American spelling) is a chemical element with symbol Cs and atomic number 55.

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Carl Friedrich Gauss

Johann Carl Friedrich Gauss (Gauß; Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields, including algebra, analysis, astronomy, differential geometry, electrostatics, geodesy, geophysics, magnetic fields, matrix theory, mechanics, number theory, optics and statistics.

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Centimetre–gram–second system of units

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.

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Civil time

In modern usage, civil time refers to statutory time scales designated by civilian authorities, or to local time indicated by clocks.

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Coordinated Universal Time

No description.

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Day

A day, a unit of time, is approximately the period of time during which the Earth completes one rotation with respect to the Sun (solar day).

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Ephemeris time

The term ephemeris time (often abbreviated ET) can in principle refer to time in connection with any astronomical ephemeris.

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Epoch (astronomy)

In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.

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Escapement

An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element (the "impulse action") and allows the number of its oscillations to be counted (the "locking action").

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Frequency

Frequency is the number of occurrences of a repeating event per unit of time.

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Full moon

The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective.

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Gravitational time dilation

Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass.

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Heart

The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system.

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Hour

An hour (symbol: h; also abbreviated hr.) is a unit of time conventionally reckoned as of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions.

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Hyperfine structure

In atomic physics, hyperfine structure refers to small shifts and splittings in the energy levels of atoms, molecules and ions, due to interaction between the state of the nucleus and the state of the electron clouds.

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International Astronomical Union

The International Astronomical Union (IAU; Union astronomique internationale, UAI) is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.

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International Bureau of Weights and Measures

The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.

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International System of Units

The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.

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Isotopes of caesium

Caesium (55Cs; or cesium) has 40 known isotopes, making it, along with barium and mercury, the element with the most isotopes.

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January 0

January 0 is an alternative name for December 31.

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Jost Bürgi

Jost Bürgi (also Joost, Jobst; Latinized surname Burgius or Byrgius; 28 February 1552 – 31 January 1632), active primarily at the courts in Kassel and Prague, was a Swiss clockmaker, a maker of astronomical instruments and a mathematician.

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Julian year (astronomy)

In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of SI seconds each.

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Leap second

A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time as realized by UT1.

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Metric prefix

A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit.

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Metric time

Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds.

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Minute

The minute is a unit of time or angle.

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MKS system of units

The MKS system of units is a physical system of units that expresses any given measurement using base units of the metre, kilogram, and/or second (MKS).

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New moon

In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude.

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Newcomb's Tables of the Sun

Newcomb's Tables of the Sun is the short title and running head of a work by the American astronomer and mathematician Simon Newcomb entitled "Tables of the Motion of the Earth on its Axis and Around the Sun" on pages 1–169 of "Tables of the Four Inner Planets" (1895), volume VI of the serial publication Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac.

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Orders of magnitude (time)

An order of magnitude of time is (usually) a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years.

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Orpheus

Orpheus (Ὀρφεύς, classical pronunciation) is a legendary musician, poet, and prophet in ancient Greek religion and myth.

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Persian people

The Persians--> are an Iranian ethnic group that make up over half the population of Iran.

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Revolution in Time

Revolution in Time: Clocks and the Making of the Modern World, is an influential history book by David S. Landes.

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Roger Bacon

Roger Bacon (Rogerus or Rogerius Baconus, Baconis, also Rogerus), also known by the scholastic accolade Doctor, was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empiricism.

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Sexagesimal

Sexagesimal (base 60) is a numeral system with sixty as its base.

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SI base unit

The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived.

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Sidereal year

A sidereal year (from Latin sidus "asterism, star") is the time taken by the Earth to orbit the Sun once with respect to the fixed stars.

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Strontium

Strontium is the chemical element with symbol Sr and atomic number 38.

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Sundial

A sundial is a device that tells the time of day when there is sunlight by the apparent position of the Sun in the sky.

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System of measurement

A system of measurement is a collection of units of measurement and rules relating them to each other.

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Taqi ad-Din Muhammad ibn Ma'ruf

Taqi al-Din Muhammad ibn Ma'ruf ash-Shami al-Asadi (Arabic: تقي الدين محمد بن معروف الشامي, Turkish: Takiyüddin or Taki) (1526–1585) was an Ottoman polymath active in Constantinople.

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Time

Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.

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Time standard

A time standard is a specification for measuring time: either the rate at which time passes; or points in time; or both.

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Tropical year

A tropical year (also known as a solar year) is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice.

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Tycho Brahe

Tycho Brahe (born Tyge Ottesen Brahe;. He adopted the Latinized form "Tycho Brahe" (sometimes written Tÿcho) at around age fifteen. The name Tycho comes from Tyche (Τύχη, meaning "luck" in Greek, Roman equivalent: Fortuna), a tutelary deity of fortune and prosperity of ancient Greek city cults. He is now generally referred to as "Tycho," as was common in Scandinavia in his time, rather than by his surname "Brahe" (a spurious appellative form of his name, Tycho de Brahe, only appears much later). 14 December 154624 October 1601) was a Danish nobleman, astronomer, and writer known for his accurate and comprehensive astronomical and planetary observations.

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United States Naval Observatory

The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation and Timing (PNT) for the United States Navy and the United States Department of Defense.

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Universal Time

Universal Time (UT) is a time standard based on Earth's rotation.

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University of Pennsylvania Press

The University of Pennsylvania Press (or Penn Press) is a university press affiliated with the University of Pennsylvania located in Philadelphia, Pennsylvania.

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Velocity

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time.

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Watch

A watch is a timepiece intended to be carried or worn by a person.

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William IV, Landgrave of Hesse-Kassel

William IV of Hesse-Kassel (24 June 1532 – 25 August 1592), also called William the Wise, was the first Landgrave of the Landgraviate of Hesse-Kassel (or Hesse-Cassel).

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1 E0 s, 1 E6 s, 1 E7 s, 1 E8 s, 1 second, 1e6 s, 1e7 s, 1e8 s, 9192631770, Calendar Second, Fourth (time), Gigasecond, Megasecond, Number of seconds in a year, S (unit), Second (SI unit), Second (time), Second duration, Second of time, Secound, Secs, Third (time).

References

[1] https://en.wikipedia.org/wiki/Second

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