Ephemeris

Source: Wikipedia, the free encyclopedia.
For the 18th-century Greek newspaper, see Efimeris.

In

position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers
. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available.

The astronomical position calculated from an ephemeris is often given in the

celestial bodies such as Chiron
.

Ephemerides are used in celestial navigation and astronomy. They are also used by astrologers.[4] GPS signals include ephemeris data used to calculate the position of satellites in orbit.

History

al-Khwārizmī's zīj, page from Corpus Christi College
MS 283
Alfonsine tables
Page from Almanach Perpetuum

Modern ephemeris

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.

After introduction of electronic computers in the 1950s it became feasible to use

VSOP
are examples.

Typically, such ephemerides cover several centuries, past and future; the future ones can be covered because the field of

JPL) has revised its published ephemerides nearly every year since 1981.[8]

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

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.

Nautical Almanac or Air Almanac.[10]

An ephemeris is usually only correct for a particular location on the Earth. In many cases, the differences are too small to matter. However, for nearby asteroids or the Moon, they can be quite important.

Other modern ephemerides recently created are the EPM (Ephemerides of Planets and the Moon), from the Russian Institute for Applied Astronomy of the

Observatoire de Paris) by the French IMCCE.[12][13]

See also

Notes

  1. Perseus Project
    .
  2. ^ "ephemeris". Merriam-Webster.
  3. ^ "ephemeris". Dictionnaire Gaffiot latin-français.
  4. ISBN 978-3-319-59909-0
    .
  5. ^ Jones, S.S.D.; Howard, John; William, May; Logsdon, Tom; Anderson, Edward; Richey, Michael. "Navigation". Encyclopedia Britannica. Encyclopædia Britannica, inc. Retrieved 13 March 2019.
  6. ISBN 9780521411585
    .
  7. S2CID 20888261
    . Retrieved 23 June 2016.
  8. 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)
    .
  9. ^ American Practical Navigator: An Epitiome of Navigation. Bethesda, MD: National Imagery and Mapping Agency. 2002. p. 270.
  10. ^ "Almanacs and Other Publications — Naval Oceanography Portal". United States Naval Observatory. Archived from the original on 27 January 2022. Retrieved 11 November 2016.
  11. doi:10.1017/S1743921307011453
    .
  12. ^ "INPOP10e, a 4-D planetary ephemeris". IMCCE. Retrieved 2 May 2013.
  13. doi:10.13140/RG.2.2.24384.43521
    .

References

External links

Wikimedia Commons has media related to Ephemeris.
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