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An ephemeris (plural: ephemerides; from the Greek word ephemeros = daily) is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly s are significant physical entities, associations or structures which current Science has confirmed to exist in Space. The sky is the part of the Atmosphere or of Outer space visible from the surface of any Astronomical object. Different kinds are used for astronomy and astrology. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems Even though this was also one of the first applications of mechanical computers, an ephemeris will still often be a simple printed table. The history of Computing is longer than the History of computing hardware and modern computing technology and includes the history of methods intended for

The position is given to astronomers in a spherical polar coordinate system of right ascension and declination or to astrologer in longitude along the zodiacal ecliptic, and sometimes declination. In Mathematics, the polar coordinate system is a two-dimensional Coordinate system in which each point on a plane is determined by Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either An astrologer practices one or more forms of Astrology. Typically an astrologer draws a Horoscope for the time of an event such as a person's birth and interprets Longitude (ˈlɒndʒɪˌtjuːd or ˈlɒŋgɪˌtjuːd symbolized by the Greek character Lambda (λ is the east-west Geographic coordinate measurement Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic The ecliptic is the apparent path that the Sun traces out in the sky during the year In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either Astrological positions may be given for either noon or midnight. Noon (also midday) is the hour of 1200 in an observer's local time zone or more loosely a time near the middle of the day when workers in many countries take a meal break Midnight is literally "the middle of the night" In most systems it is when one day ends and the next begins when the date changes

An ephemeris may also provide data on astronomical phenomena of interest to astrologers and astronomers such as eclipses, apparent retrogradation/planetary stations, planetary ingresses, sidereal time, positions for the Mean and True nodes of the moon, the phases of the Moon, and sometimes even the position(s) of Chiron, Lilith, and other minor or imaginary celestial bodies. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study An astrologer practices one or more forms of Astrology. Typically an astrologer draws a Horoscope for the time of an event such as a person's birth and interprets Historically Astronomy was more concerned with the classification and description of phenomena in the sky while Astrophysics attempted to explain these phenomena An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion. Sidereal time is a measure of the position of the Earth in its rotation around its axis or time measured by the apparent Diurnal motion of the Vernal equinox The lunar nodes are the Orbital nodes of the Moon, that is the points where the orbit of the Moon crosses the Ecliptic (which is the apparent Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth TemplateInfobox Planet. --> 2060 Chiron (, or as in Χείρων) is a Planetoid in the You may also be looking for an asteroid designated 1181 Lilith Lilith is a hypothetical natural satellite of Earth s are significant physical entities, associations or structures which current Science has confirmed to exist in Space. Some ephemerides also contain a monthly aspectarian, while others often include the declination of the planets as well as their longitudes, right ascensions or Cartesian coordinates. In Astrology, an aspect is an Angle the planets make to each other in the horoscope and also to the ascendant midheaven descendant and nadir In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere In Mathematics, the Cartesian coordinate system (also called rectangular coordinate system) is used to determine each point uniquely in a plane

Contents

History

In 1554, Johannes Stadius published a well-known work known as Ephemerides novae at auctae that attempted to give accurate planetary positions. Johannes Stadius or Estadius ( Dutch, Jan Van Ostaeyen; French, Jean Stade) (ca The effort was not entirely successful, and there were, for example, periodic errors in Stadius’ Mercury positions of up to ten degrees.

Scientific ephemeris

For scientific uses, a modern planetary ephemeris comprises software that generates positions of the planets and often of their satellites, or of asteroids or comets at virtually any time desired by the user. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Often there is an option to find the velocities of the bodies of interest, as well.

Typically, such ephemerides cover several centuries, past and future; the future ones can be covered because celestial mechanics is an accurate theory. Celestial mechanics is the branch of Astrophysics that deals with the motions of Celestial objects The field applies principles of Physics, historically Nevertheless, there are secular phenomena, factors that cannot adequately be considered by ephemerides. In Astronomy, secular phenomena (which repeat too slowly to be observed if at all are contrasted with phenomena observed to repeat periodically The biggest uncertainties on planetary positions are due to the perturbations of numerous asteroids, most of whose masses are poorly known, rendering their effect uncertain. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Therefore, despite efforts to overcome these uncertainties, the JPL has to revise its published ephemerides at intervals of 20 years.

Solar system ephemerides are essential for the navigation of spacecraft and for all kinds of space observations of the planets, their natural satellites, stars and galaxies. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. A spacecraft is a Vehicle or machine designed for Spaceflight. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth A galaxy is a massive gravitationally bound system consisting of Stars an Interstellar medium of gas and dust, and Dark matter

Scientific ephemerides for sky observers mostly contain the position of the mentioned celestial body in right ascension and declination, because these coordinates are the most often used on star maps and telescopes. Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either The equinox of the coordinate system must be given. An equinox is the event of the Sun passing over the Earth's equator in its annual cycle It is in nearly all cases either the actual equinox (the equinox valid for that moment, often referred to as "of date" or "current"), or that of the one of the "standard" equinoxes, typically J2000.0, B1950.0, or J1900. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. Star maps are almost always in one of the standard equinoxes.

Scientific ephemerides often contain further useful data about the moon, planet, asteroid, or comet beyond the pure coordinates in the sky, such as elongation to the sun, brightness, distance, velocity, apparent diameter in the sky, phase angle, times of rise, transit, and set, etc. Ephemerides of the planet Saturn also sometimes contain the apparent inclination of its ring.

An ephemeris is usually only correct for a particular location on the Earth. In many cases the differences are too small to matter, but for nearby asteroids or the Moon they can be quite important. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but

GPS navigation satellites transmit electronic ephemeris data consisting of health and exact location data that GPS receivers then use (together with the signal's elapsed travel time to the receiver) to calculate their own location on Earth using trilateration. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth Trilateration is a method of determining the relative positions of objects using the Geometry of Triangles in a similar fashion as Triangulation.

Astrological ephemeris

The majority of astrologers study tropical astrology, involving planetary positions referenced to the vernal (spring) equinox position along the ecliptic (the equinox being the nexus of Earth's rotational plane and Earth's orbital plane around the Sun). Tropical astrology is a type of Astrology based on a Zodiac whose points of reference are the Tropics. An equinox is the event of the Sun passing over the Earth's equator in its annual cycle They use exactly the same referential frame of the astronomers, a part a small minority of astrologers who study sidereal astrology and use a different ephemerids, based on the constellations. Sidereal astrology is the system of Astrology used by some Western and all Jyotish astrologers who base their interpretation around the use of the

Though astrology is and always has been geocentric, heliocentric astrology is an emerging field; for this purpose a standard ephemeris cannot be utilized, and because of this specialized heliocentric ephemerids must be calculated and used instead of the default geocentric ephemerides that are used in standard Western astrology to construct the astrological chart/natal chart. Astrology (from Greek grc ἄστρον astron, "constellation star" and grc -λογία -logia) is a group of Systems In Astronomy, the geocentric model of the Universe is the superseded theory that the Earth is the center of the universe and other In Astronomy, heliocentrism is the theory that the Sun is at the center of the Solar System. Western astrology is the system of Astrology most popular in Western countries In Astrology, a horoscope is a chart or diagram representing the positions of the Sun Moon planets the Astrological aspects, and sensitive angles In Natal astrology, a natal chart is a Horoscope /astrological chart drawn for the exact time of an individual's birth at a particular place on Earth

See also

References

External links

Dictionary

ephemeris

-noun

  1. (astronomy) A table giving the apparent position of celestial bodies throughout the year; normally given as right ascension and declination
  2. Software that calculates the apparent position of celestial bodies.
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