Editing Eclipse (section)

== Eclipse cycles ==
{{Main|Eclipse cycle}}
[[File:Eclipse vs new or full moons, annotated.svg|thumb|As the Earth revolves around the Sun, approximate [[axial parallelism]] of the Moon's [[Orbital inclination|tilted]] orbital plane (inclined at five degrees to the [[ecliptic|Earth's orbital plane]]) results in the revolution of the [[lunar nodes]] relative to the Earth. This causes an [[eclipse season]] approximately every six months, in which a [[solar eclipse]] can occur at the [[new moon]] phase and a lunar eclipse can occur at the [[full moon]] phase.]]
An [[eclipse cycle]] takes place when eclipses in a series are separated by a certain interval of time. This happens when the orbital motions of the bodies form repeating harmonic patterns. A particular instance is the [[saros (astronomy)|saros]], which results in a repetition of a solar or lunar eclipse every 6,585.3&nbsp;days, or a little over 18 years. Because this is not a whole number of days, successive eclipses will be visible from different parts of the world.<ref>{{cite web
 |last=Espenak 
 |first=Fred 
 |date=July 12, 2007 
 |url=http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros.html 
 |title=Eclipses and the Saros 
 |publisher=NASA 
 |access-date=2007-12-13 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20071030225501/http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros.html 
 |archive-date=2007-10-30 
}}</ref> In one saros period there are 239.0 anomalistic periods, 241.0 sidereal periods, 242.0 nodical periods, and 223.0 synodic periods. Although the [[orbit of the Moon]] does not give exact integers, the numbers of orbit cycles are close enough to integers to give strong similarity for eclipses spaced at 18.03 yr intervals.