The angular distance of a point east of the First Point of Aries, measured along the ecliptic.
〔天文〕黄经。比较RIGHT ASCENSION
Compare with right ascension
Example sentencesExamples
By the time he returned home in January 1678, he had recorded the celestial longitudes and latitudes of 341 stars and observed a transit of Mercury across the Sun's disk.
In this case, Mayan astronomers apparently focused on two cycles related to the number of days that elapse between consecutive passages of Mars through a given celestial longitude while traveling across the sky.
Technically, a conjunction describes a precise alignment of heavenly bodies that happen to have the same celestial longitude - that is, they appear to line up in the sky, one directly above the other.
But in fact, from day to day the earthbound observer does see the midday Sun at a different point along the same celestial longitude - up or down relative to the horizon.
The Moon's motion along the ecliptic is measured in degrees and minutes of celestial longitude, but its orbit does not align exactly with the ecliptic.
Definition of celestial longitude in US English:
celestial longitude
noun
Astronomy
The angular distance of a point east of the vernal equinox, measured along the ecliptic.
〔天文〕黄经。比较RIGHT ASCENSION
Compare with right ascension
Example sentencesExamples
Technically, a conjunction describes a precise alignment of heavenly bodies that happen to have the same celestial longitude - that is, they appear to line up in the sky, one directly above the other.
In this case, Mayan astronomers apparently focused on two cycles related to the number of days that elapse between consecutive passages of Mars through a given celestial longitude while traveling across the sky.
By the time he returned home in January 1678, he had recorded the celestial longitudes and latitudes of 341 stars and observed a transit of Mercury across the Sun's disk.
The Moon's motion along the ecliptic is measured in degrees and minutes of celestial longitude, but its orbit does not align exactly with the ecliptic.
But in fact, from day to day the earthbound observer does see the midday Sun at a different point along the same celestial longitude - up or down relative to the horizon.