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In astronomy and celestial navigation, an ephemeris (plural: ephemerides; from Latin ''ephemeris'', "diary", from Greek ἐφημερίς, ''ephēmeris'', "diary, calendar")〔(【引用サイトリンク】title=Dictionary − ephemeris )〕〔(【引用サイトリンク】url=http://www.lexilogos.com/latin/gaffiot.php?q=ephemeris )〕 gives the positions of naturally occurring astronomical objects as well as artificial satellites in the sky at a given time or times. Historically, positions were given as printed tables of values, given at regular intervals of date and time. Modern ephemerides are often computed electronically from mathematical models of the motion of astronomical objects and the Earth. Even though the calculation of these tables was one of the first applications of mechanical computers, printed ephemerides are still produced, as they are useful when computational devices are not available. The astronomical position calculated from an ephemeris is given in the spherical polar coordinate system of right ascension and declination. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary ingresses, sidereal time, positions for the mean and true nodes of the moon, the phases of the Moon, and the positions of minor celestial bodies such as Chiron. Ephemerides are used in celestial navigation, astronomy and astrology. Astrologers typically have different needs than astronomers, for example, the calculation of astrological aspects, and may produce ephemerides specialized to their own field. == History == *2nd Millennium BC — Panchanga tables based on Jyotisha in the Vedic period of Indian astronomy. *1st Millennium BC — Ephemerides in Babylonian astronomy. *2nd Century AD — the ''Almagest'' and the ''Handy Tables'' of Ptolemy *8th Century AD — the Zij of Ibrāhīm al-Fazārī *9th Century AD — the Zij of Muḥammad ibn Mūsā al-Khwārizmī *12th Century AD — the Tables of Toledo, based largely on Arabic Zij sources of Islamic astronomy, were edited by Gerard of Cremona to form the standard European ephemeris until the Alfonsine tables. *13th Century — the Zij-i Ilkhani, or Ilkhanic Tables, were compiled at the Maragheh observatory in Persia. *13th Century — the Alfonsine tables were compiled in Spain to correct anomalies in the Tables of Toledo, remaining the standard European ephemeris until the Prutenic Tables almost 300 years later. *1408 — Chinese Ephemeris Table (copy in Pepysian Library, Cambridge, UK (refer book '1434'); Chinese tables believed known to Regiomontanus). *1496 — the Almanach Perpetuum of Abraão ben Samuel Zacuto (one of the first books published with a movable type and printing press in Portugal) *1504 — While shipwrecked on the island of Jamaica, Christopher Columbus successfully predicted a lunar eclipse for the natives, using the Ephemeris of the German astronomer Regiomontanus. *1551 — the Prutenic Tables of Erasmus Reinhold were published, based on Copernicus's theories. *1554 — Johannes Stadius published ''Ephemerides novae et auctae'', the first major ephemeris computed according to Copernicus' heliocentric model, using parameters derived from the Prutenic Tables. Although the Copernican model provided an elegant solution to the problem of computing apparent planetary positions (it avoided the need for the equant and better explained the apparent retrograde motion of planets), it still relied on the use of epicycles, leading to some inaccuracies - for example, periodic errors in the position of Mercury of up to ten degrees. *1627 — the Rudolphine Tables of Johannes Kepler based on elliptical planetary motion became the new standard. *1679 — ''La Connaissance des Temps ou calendrier et éphémérides du lever & coucher du Soleil, de la Lune & des autres planètes'', first published by Jean Picard. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ephemeris」の詳細全文を読む スポンサード リンク
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