"Chubun" (秋分), the autumn equinox, is the season between Baengno (白露) and Hallo (寒露), and is one of the twenty-four seasonal sub-divisions, or solar terms, of the lunar calendar. It usually falls in the eighth month of the lunar calendar, or around September 23 in the solar calendar. It is the period when the sun reaches the autumnal equinox (秋分點), and when day and night are of equal length. Past "Chubun," the night gradually becomes longer, indicating the passing of summer and the onset of fall.

추분 관련 자료

"Landscape of Chubun" by Lee Eok-yeong	"Haeng Ryeo Pung Sok Do Byeong ("Screen Depicting the Wandering Life" by Kim Hong-do

In reality, though, autumn lasts from "Chubun" until "Dongji" in Korea, whereas, in the West, it lasts from "Chubun" to "Daeseol." Because of this difference, people used to predict the future by looking at the windy weather on "Chubun." They said, "If the wind blows in from the northwest or the southeast, there will be strong winds the following year, but if it blows in from the north, the coming winter will be very cold." During the Joseon dynasty, people performed the "Yeongseongje" (靈星祭) ritual to express their gratitude for the year’s successful farming and the "Choje" (醮祭) ritual to wish for long life on "Chubun."