Editing Ecliptic coordinate system (section)

=== Historical use ===
From antiquity through the 18th&nbsp;century, ecliptic longitude was commonly measured using twelve [[Astrological sign|zodiacal signs]], each of 30°&nbsp;longitude, a practice that continues in modern [[astrology]]. The signs approximately corresponded to the [[constellation]]s crossed by the ecliptic. Longitudes were specified in signs, degrees, minutes, and seconds. For example, a longitude of {{nowrap|♌ 19°&thinsp;55′&thinsp;58″}} is 19.933°&nbsp;east of the start of the sign [[Leo (astrology)|Leo]]. Since Leo begins 120°&nbsp;from the March equinox, the longitude in modern form is {{nowrap|139°&thinsp;55′&thinsp;58″}}.<ref>{{cite book |url=https://archive.org/details/acompleatsystem01leadgoog |title=A Compleat System of Astronomy |first=Charles |last=Leadbetter |year=1742 |publisher=J. Wilcox, London |page=[https://archive.org/details/acompleatsystem01leadgoog/page/n102 94]}}; numerous examples of this notation appear throughout the book.</ref>

{{See also|solar term}}

In China, ecliptic longitude is measured using 24&nbsp;[[Solar term]]s, each of 15°&nbsp;longitude, and are used by [[Chinese calendar|Chinese lunisolar calendars]] to stay synchronized with the seasons, which is crucial for agrarian societies.