Logo
Unionpedia
Communication
Get it on Google Play
New! Download Unionpedia on your Android™ device!
Install
Faster access than browser!
 

Epoch (astronomy)

+ Save concept

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. [1]

63 relations: Aberration of light, Apsis, Astrometry, Astronomical object, Astronomy, Axial precession, Bede, Celestial coordinate system, Celestial mechanics, Civil time, Constellation, Coordinated Universal Time, Earth, Ecliptic, Ecliptic coordinate system, Ephemeris, Epoch (reference date), Equator, Equatorial coordinate system, Equinox (celestial coordinates), Friedrich Bessel, Gregorian calendar, Hebrew calendar, Heliacal rising, Henry Draper Catalogue, Hipparcos, Infinity, International Astronomical Union, International Atomic Time, International Celestial Reference Frame, International Celestial Reference System, Islamic calendar, ΔT, Julian calendar, Julian day, Julian year (astronomy), Longitude of the ascending node, Lunar calendar, Lunisolar calendar, March equinox, Mean anomaly, Mean longitude, Meridian (astronomy), Midnight, Minor planet, Noon, Orbital elements, Orbital mechanics, Osculating orbit, Perihelion and aphelion, ..., Perturbation (astronomy), Plane of reference, Polynomial, Precession, Proper motion, Semi-major and semi-minor axes, Sirius, SOFA (astronomy), Sun, Terrestrial Time, Universal Time, Year, 5145 Pholus. Expand index (13 more) »

Aberration of light

The aberration of light (also referred to as astronomical aberration, stellar aberration, or velocity aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects about their true positions, dependent on the velocity of the observer.

New!!: Epoch (astronomy) and Aberration of light · See more »

Apsis

An apsis (ἁψίς; plural apsides, Greek: ἁψῖδες) is an extreme point in the orbit of an object.

New!!: Epoch (astronomy) and Apsis · See more »

Astrometry

Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies.

New!!: Epoch (astronomy) and Astrometry · See more »

Astronomical object

An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.

New!!: Epoch (astronomy) and Astronomical object · See more »

Astronomy

Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

New!!: Epoch (astronomy) and Astronomy · See more »

Axial precession

In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis.

New!!: Epoch (astronomy) and Axial precession · See more »

Bede

Bede (italic; 672/3 – 26 May 735), also known as Saint Bede, Venerable Bede, and Bede the Venerable (Bēda Venerābilis), was an English Benedictine monk at the monastery of St.

New!!: Epoch (astronomy) and Bede · See more »

Celestial coordinate system

In astronomy, a celestial coordinate system is a system for specifying positions of celestial objects: satellites, planets, stars, galaxies, and so on.

New!!: Epoch (astronomy) and Celestial coordinate system · See more »

Celestial mechanics

Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects.

New!!: Epoch (astronomy) and Celestial mechanics · See more »

Christmas

Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.

New!!: Epoch (astronomy) and Christmas · See more »

Christmas and holiday season

The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.

New!!: Epoch (astronomy) and Christmas and holiday season · See more »

Christmas Eve

Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.

New!!: Epoch (astronomy) and Christmas Eve · See more »

Christmas traditions

Christmas traditions vary from country to country.

New!!: Epoch (astronomy) and Christmas traditions · See more »

Civil time

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

New!!: Epoch (astronomy) and Civil time · See more »

Constellation

A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.

New!!: Epoch (astronomy) and Constellation · See more »

Coordinated Universal Time

No description.

New!!: Epoch (astronomy) and Coordinated Universal Time · See more »

Earth

Earth is the third planet from the Sun and the only astronomical object known to harbor life.

New!!: Epoch (astronomy) and Earth · See more »

Ecliptic

The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.

New!!: Epoch (astronomy) and Ecliptic · See more »

Ecliptic coordinate system

The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions and orbits of Solar System objects.

New!!: Epoch (astronomy) and Ecliptic coordinate system · See more »

Ephemeris

In astronomy and celestial navigation, an ephemeris (plural: ephemerides) gives the positions of naturally occurring astronomical objects as well as artificial satellites in the sky at a given time or times.

New!!: Epoch (astronomy) and Ephemeris · See more »

Epoch (reference date)

In the fields of chronology and periodization, an epoch is an instant in time chosen as the origin of a particular era.

New!!: Epoch (astronomy) and Epoch (reference date) · See more »

Equator

An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel).

New!!: Epoch (astronomy) and Equator · See more »

Equatorial coordinate system

The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects.

New!!: Epoch (astronomy) and Equatorial coordinate system · See more »

Equinox (celestial coordinates)

In astronomy, equinox is a moment when the vernal point, celestial equator, and other such elements are taken to be used in the definition of a celestial coordinate system.

New!!: Epoch (astronomy) and Equinox (celestial coordinates) · See more »

Friedrich Bessel

Friedrich Wilhelm Bessel (22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist and geodesist.

New!!: Epoch (astronomy) and Friedrich Bessel · See more »

Gregorian calendar

The Gregorian calendar is the most widely used civil calendar in the world.

New!!: Epoch (astronomy) and Gregorian calendar · See more »

Hebrew calendar

The Hebrew or Jewish calendar (Ha-Luah ha-Ivri) is a lunisolar calendar used today predominantly for Jewish religious observances.

New!!: Epoch (astronomy) and Hebrew calendar · See more »

Heliacal rising

The heliacal rising or star rise of a star, star cluster, or galaxy occurs annually when it becomes visible above the eastern horizon for a moment before sunrise, after a period of less than a year when it had not been visible.

New!!: Epoch (astronomy) and Heliacal rising · See more »

Henry Draper Catalogue

The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars.

New!!: Epoch (astronomy) and Henry Draper Catalogue · See more »

Hipparcos

Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.

New!!: Epoch (astronomy) and Hipparcos · See more »

Infinity

Infinity (symbol) is a concept describing something without any bound or larger than any natural number.

New!!: Epoch (astronomy) and Infinity · See more »

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.

New!!: Epoch (astronomy) and International Astronomical Union · See more »

International Atomic Time

International Atomic Time (TAI, from the French name temps atomique international) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid.

New!!: Epoch (astronomy) and International Atomic Time · See more »

International Celestial Reference Frame

In astrometry, an International Celestial Reference Frame (ICRF) is a realization of the International Celestial Reference System (ICRS) using reference celestial sources observed at radio wavelengths.

New!!: Epoch (astronomy) and International Celestial Reference Frame · See more »

International Celestial Reference System

The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU).

New!!: Epoch (astronomy) and International Celestial Reference System · See more »

Islamic calendar

The Islamic, Muslim, or Hijri calendar (التقويم الهجري at-taqwīm al-hijrī) is a lunar calendar consisting of 12 months in a year of 354 or 355 days.

New!!: Epoch (astronomy) and Islamic calendar · See more »

ΔT

In precise timekeeping, ΔT (Delta T, delta-T, deltaT, or DT) is the time difference obtained by subtracting Universal Time (UT) from Terrestrial Time (TT):.

New!!: Epoch (astronomy) and ΔT · See more »

Julian calendar

The Julian calendar, proposed by Julius Caesar in 46 BC (708 AUC), was a reform of the Roman calendar.

New!!: Epoch (astronomy) and Julian calendar · See more »

Julian day

Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers.

New!!: Epoch (astronomy) and Julian day · See more »

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.

New!!: Epoch (astronomy) and Julian year (astronomy) · See more »

Longitude of the ascending node

The longitude of the ascending node (☊ or Ω) is one of the orbital elements used to specify the orbit of an object in space.

New!!: Epoch (astronomy) and Longitude of the ascending node · See more »

Lunar calendar

A lunar calendar is a calendar based upon the monthly cycles of the Moon's phases (synodic months), in contrast to solar calendars, whose annual cycles are based only directly upon the solar year.

New!!: Epoch (astronomy) and Lunar calendar · See more »

Lunisolar calendar

A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year.

New!!: Epoch (astronomy) and Lunisolar calendar · See more »

March equinox

The March equinox or Northward equinox is the equinox on the Earth when the subsolar point appears to leave the southern hemisphere and cross the celestial equator, heading northward as seen from Earth.

New!!: Epoch (astronomy) and March equinox · See more »

Mean anomaly

In celestial mechanics, the mean anomaly is an angle used in calculating the position of a body in an elliptical orbit in the classical two-body problem.

New!!: Epoch (astronomy) and Mean anomaly · See more »

Mean longitude

Mean longitude is the ecliptic longitude at which an orbiting body could be found if its orbit were circular and free of perturbations.

New!!: Epoch (astronomy) and Mean longitude · See more »

Meridian (astronomy)

In astronomy, the meridian is the great circle passing through the celestial poles, the zenith, and the nadir of an observer's location.

New!!: Epoch (astronomy) and Meridian (astronomy) · See more »

Midnight

Midnight is the transition time from one day to the next – the moment when the date changes.

New!!: Epoch (astronomy) and Midnight · See more »

Minor planet

A minor planet is an astronomical object in direct orbit around the Sun (or more broadly, any star with a planetary system) that is neither a planet nor exclusively classified as a comet.

New!!: Epoch (astronomy) and Minor planet · See more »

New Year

New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.

New!!: Epoch (astronomy) and New Year · See more »

New Year's Day

New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.

New!!: Epoch (astronomy) and New Year's Day · See more »

New Year's Eve

In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.

New!!: Epoch (astronomy) and New Year's Eve · See more »

Noon

Noon (also midday or noon time) is 12 o'clock in the daytime, as opposed to midnight.

New!!: Epoch (astronomy) and Noon · See more »

Orbital elements

Orbital elements are the parameters required to uniquely identify a specific orbit.

New!!: Epoch (astronomy) and Orbital elements · See more »

Orbital mechanics

Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.

New!!: Epoch (astronomy) and Orbital mechanics · See more »

Osculating orbit

In astronomy, and in particular in astrodynamics, the osculating orbit of an object in space at a given moment in time is the gravitational Kepler orbit (i.e. ellipse or other conic) that it would have about its central body if perturbations were not present.

New!!: Epoch (astronomy) and Osculating orbit · See more »

Perihelion and aphelion

The perihelion of any orbit of a celestial body about the Sun is the point where the body comes nearest to the Sun.

New!!: Epoch (astronomy) and Perihelion and aphelion · See more »

Perturbation (astronomy)

In astronomy, perturbation is the complex motion of a massive body subject to forces other than the gravitational attraction of a single other massive body.

New!!: Epoch (astronomy) and Perturbation (astronomy) · See more »

Plane of reference

In celestial mechanics, the plane of reference (or reference plane) is the plane used to define orbital elements (positions).

New!!: Epoch (astronomy) and Plane of reference · See more »

Polynomial

In mathematics, a polynomial is an expression consisting of variables (also called indeterminates) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables.

New!!: Epoch (astronomy) and Polynomial · See more »

Precession

Precession is a change in the orientation of the rotational axis of a rotating body.

New!!: Epoch (astronomy) and Precession · See more »

Proper motion

Proper motion is the astronomical measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars.

New!!: Epoch (astronomy) and Proper motion · See more »

Semi-major and semi-minor axes

In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter.

New!!: Epoch (astronomy) and Semi-major and semi-minor axes · See more »

Sirius

Sirius (a romanization of Greek Σείριος, Seirios,."glowing" or "scorching") is a star system and the brightest star in the Earth's night sky.

New!!: Epoch (astronomy) and Sirius · See more »

SOFA (astronomy)

The SOFA (Standards of Fundamental Astronomy) software libraries are a collection of subroutines that implement official International Astronomical Union algorithms for astronomical computations.

New!!: Epoch (astronomy) and SOFA (astronomy) · See more »

Sun

The Sun is the star at the center of the Solar System.

New!!: Epoch (astronomy) and Sun · See more »

Terrestrial Time

Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth.

New!!: Epoch (astronomy) and Terrestrial Time · See more »

Universal Time

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

New!!: Epoch (astronomy) and Universal Time · See more »

Year

A year is the orbital period of the Earth moving in its orbit around the Sun.

New!!: Epoch (astronomy) and Year · See more »

2018

2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.

New!!: Epoch (astronomy) and 2018 · See more »

2019

2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.

New!!: Epoch (astronomy) and 2019 · See more »

5145 Pholus

5145 Pholus (from Φόλος) provisional designation, is an eccentric centaur in the outer Solar System, approximately 180 kilometers in diameter, that crosses the orbit of both Saturn and Neptune.

New!!: Epoch (astronomy) and 5145 Pholus · See more »

Redirects here:

1875.0, 1900.0, 1950.0, 2000.0, Astronomical epoch, B1875, B1875.0, B1900, B1900.0, B1950, B1950.0, B2000.0, Besselian epoch, Besselian year, Epoch astronomy, Epochal moment, J1900, J1900.0, J1950, J1950.0, J2000, J2000.0, Julian epoch, Standard epoch 2000.

References

[1] https://en.wikipedia.org/wiki/Epoch_(astronomy)

OutgoingIncoming
Hey! We are on Facebook now! »