Definition of ecliptic in English:



  • A great circle on the celestial sphere representing the sun's apparent path during the year, so called because lunar and solar eclipses can only occur when the moon crosses it.

    • ‘An eclipse occurs only if the Moon crosses the ecliptic when very close to either conjunction or opposition, respectively producing solar and lunar eclipses.’
    • ‘The Moon's Nodes are points in space representing the points where the moon's orbit around the earth crosses the ecliptic.’
    • ‘The other planets though also move across the sky on paths close to the ecliptic.’
    • ‘Comets in this group, called the Jupiter family comets, revolve around the Sun near the plane of the ecliptic in the same direction as Earth's orbit.’
    • ‘A lunar eclipse occurs at full moon when the Moon crosses the ecliptic in opposition to the Sun.’


  • Of an eclipse or the ecliptic.

    • ‘Lunar eclipses occur at the time of a Full Moon, and when the Moon is near one of the nodes of intersection between its orbit and the ecliptic plane.’
    • ‘Another eight years later the node has moved beyond the ecliptic limit, and no transit can take place.’
    • ‘Second, and more significant, eclipses do not necessarily occur precisely on the node, but rather there is a range of possible positions called the ecliptic limits.’
    • ‘There are also tables which give transformations between different coordinate systems on the celestial sphere, in particular allowing ecliptic coordinates to be transformed into equatorial coordinates.’
    • ‘The required coincidence of a conjunction with the ecliptic crossing of Venus has some latitude because the solar disc is so much bigger than the image of Venus.’


Late Middle English via Latin from Greek ekleiptikos, from ekleipein ‘fail to appear’ (see eclipse).