digplanet beta 1: Athena
Share digplanet:

Agriculture

Applied sciences

Arts

Belief

Business

Chronology

Culture

Education

Environment

Geography

Health

History

Humanities

Language

Law

Life

Mathematics

Nature

People

Politics

Science

Society

Technology

For the 18th-century Greek newspaper, see Efimeris.

In astronomy and celestial navigation, an ephemeris (plural: ephemerides; from Latin ephemeris ("diary"), from Greek ἐφημερίς (ephēmeris, "diary, calendar"))[1][2][3] 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 position(s) of Chiron and other minor celestial bodies.

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[edit]

A Latin translation of al-Khwārizmī's Zīj, page from Corpus Christi College MS 283
Alfonsine tables
Page from Almanach Perpetuum

Modern ephemeris[edit]

For scientific uses, a modern planetary ephemeris comprises software that generates positions of planets and often of their satellites, asteroids, or comets, at virtually any time desired by the user.

Typically, such ephemerides cover several centuries, past and future; the future ones can be covered because the field of celestial mechanics has developed several accurate theories. Nevertheless, there are secular phenomena which cannot adequately be considered by ephemerides. The greatest uncertainties in the positions of planets are caused by the perturbations of numerous asteroids, most of whose masses and orbits are poorly known, rendering their effect uncertain. Reflecting the continuing influx of new data and observations, NASA's Jet Propulsion Laboratory (JPL) has to revise its published ephemerides at intervals of 20 years.[4]

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.

Scientific ephemerides for sky observers mostly contain the positions of celestial bodies in right ascension and declination, because these coordinates are the most frequently used on star maps and telescopes. The equinox of the coordinate system must be given. 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 one of the "standard" equinoxes, typically J2000.0, B1950.0, or J1900. Star maps almost always use 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.

Global Positioning System (GPS) navigation satellites transmit electronic ephemeris data consisting of health and exact location data. A GPS receiver can use the transmissions from multiple such satellites to calculate its own location using trilateration.

Other modern ephemerides recently created are the EPM (Ephemerides of Planets and the Moon), from the Russian Institute for Applied Astronomy of the Russian Academy of Sciences,[5] and the INPOP (Integration Numerique Planetaire de l'Observatoire de Paris) by the French IMCCE.[6]

The Photographer's Ephemeris is a free useful software tool for photographers needing the times of twilight and the rise and set times of the sun and moon.[7]

See also[edit]

Notes[edit]

  1. ^ ephemeris 1992.
  2. ^ "ephemeris". Dictionary. Merriam-Webster. 
  3. ^ "ephemeris". Dictionnaire Gaffiot latin-français. 
  4. ^ Georgij A. Krasinsky and Victor A. Brumberg, Secular Increase of Astronomical Unit from Analysis of the Major Planet Motions, and its Interpretation Celestial Mechanics and Dynamical Astronomy 90: 267–288, (2004).
  5. ^ Pitjeva, Elena V. (August 2006). "The dynamical model of the planet motions and EPM ephemerides". Highlights of Astronomy 14: 470. doi:10.1017/S1743921307011453. 
  6. ^ "INPOP10e, a 4-D planetary ephemeris". IMCCE. Retrieved 2 May 2013. 
  7. ^ Astronomical algorithms taken from Astronomical Algorithms, 2nd Ed. by Jean Meeus.

References[edit]

  • Duffett-Smith, Peter (1990). Astronomy With Your Personal Computer. Cambridge University Press. ISBN 0-521-38995-X. 
  • "ephemeris". American Heritage Dictionary of the English Language (3rd ed.). Boston: Houghton Mifflin. 1992. 
  • MacCraig, Hugh (1949). The 200 Year Ephemeris. Macoy Publishing Company. 
  • Meeus, Jean (1991). Astronomical Algorithms. Willmann-Bell. ISBN 0-943396-35-2. 
  • Michelsen, Neil F. (1990). Tables of Planetary Phenomena. ACS Publications, Inc. ISBN 0-935127-08-9. 
  • Michelsen, Neil F. (1982). The American Ephemeris for the 21st Century - 2001 to 2100 at Midnight. Astro Computing Services. ISBN 0-917086-50-3. 
  • Montenbruck, Oliver (1989). Practical Ephemeris Calculations. Springer-Verlag. ISBN 0-387-50704-3. 
  • Seidelmann, Kenneth (2006). Explanatory supplement to the astronomical almanac. University Science Books. ISBN 1-891389-45-9. 

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Ephemeris — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
5798 videos foundNext > 

H.U.V.A. Network - Ephemeris [Full Album]

http://ultimae.bandcamp.com/album/ephemeris 01. Dissolving Time 0:00 02. .Blank 6:49 03. Orientations part 1 (Above Towns Edit) 15:54 04. Orientations part 2...

H.U.V.A. Network - [ Ephemeris ] - Album

http://www.discogs.com/HUVA-Network-Ephemeris/release/1688491 http://www.ultimae.com/en/releases/h-u-v-a-network-ephemeris/index.html Track List: 1. Dissolvi...

Learn Astrology - The Ephemeris 1

http://www.professorastrology.com presents, A new and radical - easy to understand - course in Astrology U - Watch and U - Learn Astrology. There are twelve ...

How to use The Photographer's Ephemeris Part 1

Yellow Wood Guiding video on the use of The Photographer's Ephemeris software For more info on photography visit: http://www.ywguiding.com.

Software-Tipp für Fotografen: The Photographer's Ephemeris

Ein MUST-HAVE Tool für JEDEN Fotograf und Videograf Link zur Website der Software (kostenloser Download): http://photoephemeris.com/ Google Play App (kostenp...

iPad Photography App: The Photographer's Ephemeris: Adorama Photography TV

This week Mark Wallace discovered a great iPad application that is called The Photographer's Ephemeris. AdoramaTV presents The Photographer's Ephemeris for i...

How to Use the Photographer's Ephemeris

Stephen Trainor's "The Photographers Ephemeris" is an excellent tool for predicting when and where the sun or moon will be at any time of the day at nearly a...

Future bound - Ephemeris

BEKKI WILLIAMS - Ephemeris

Pretium, Generosi (Adeimus) Gloriosi (Adeimus), Gentium (Adeimus) Amen (Adeimus). Adeimus - Adeimus, Adeimus - Adeimus, Adeimus Pretium, Generosi (Adeimus) G...

Lunarsea - Ephemeris 1679 [Italy] [HD]

Melodic death metal song. From album "Hundred Light Years" (2013)

5798 videos foundNext > 

We're sorry, but there's no news about "Ephemeris" right now.

Loading

Oops, we seem to be having trouble contacting Twitter

Talk About Ephemeris

You can talk about Ephemeris with people all over the world in our discussions.

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!