## Equation of time |

The **equation of time** describes the discrepancy between two kinds of
*equation* is used in the medieval sense of "reconcile a difference". The two times that differ are the *apparent* solar time, which directly tracks the
*mean* solar time, which tracks a theoretical
*Mean* solar time, for the same place, would be the time indicated by a steady clock set so that over the year its differences from apparent solar time would resolve to zero.^{
[1]}

The equation of time is the east or west component of the
^{
[2]}^{
[3]}

- the concept
- sign of the equation of time
- history
- major components of the equation
- secular effects
- graphical representation
- practical use
- calculating the equation of time
- see also
- notes and footnotes
- references
- external links

During a year the equation of time varies as shown on the graph; its change from one year to the next is slight. Apparent time, and the sundial, can be ahead (fast) by as much as 16
^{
[4]}^{
[5]}

The graph of the equation of time is closely approximated by the sum of two sine curves, one with a period of a year and one with a period of half a year. The curves reflect two astronomical effects, each causing a different non-uniformity in the apparent daily motion of the Sun relative to the stars:

- the
obliquity of theecliptic (the plane of the Earth's annual orbital motion around the Sun), which is inclined by about 23.44 degrees relative to the plane of the Earth'sequator ; and - the
eccentricity of theEarth's orbit around the Sun, which is about 0.0167.

The equation of time is

Other Languages

العربية: معادلة التعاقب الزمني

беларуская: Ураўненне часу

català: Equació de temps

Deutsch: Zeitgleichung

español: Ecuación de tiempo

français: Équation du temps

한국어: 균시차

hrvatski: Jednadžba vremena

italiano: Equazione del tempo

lietuvių: Laiko lygtis

magyar: Időegyenlet

Nederlands: Tijdsvereffening

日本語: 均時差

norsk: Tidsjevning

oʻzbekcha/ўзбекча: Vaqt tenglamasi

polski: Równanie czasu

português: Equação do tempo

русский: Уравнение времени

slovenčina: Časová rovnica

slovenščina: Časovna enačba

Türkçe: Zaman denklemi

中文: 均時差