1 : either of the two points on the ecliptic at which its distance from the celestial equator is greatest.
2 : the time of the sun's passing one such point on the ecliptic which occurs about June 21 to begin summer in the northern hemisphere and about December 21 to begin winter in the northern hemisphere.
Did You Know ?
In the Northern Hemisphere, the summer solstice usually occurs on June 20 or 21 and the winter solstice on December 21 or 22. In the Southern Hemisphere, where the seasons are reversed, the solstices are exactly the opposite. For several days around the time of the solstices, the sun's appearance on the horizon at sunrise and sunset seems to occur at the same spot, before it starts drifting to the north or south again. Solstice gets its shine from sol, the Latin word for "sun." The ancients added sol to -stit- (a participial stem of sistere, which means "to stand still") and came up with solstitium. Middle English speakers shortened solstitium to solstice in the 14th century.
People all over the world have observed celebrations linked to the summer and winter solstices since ancient times.
"The Earth wobbles on its axis once every 27,000 years…. This alters the relationship between the solstices and the distance from the Earth to the Sun." — Steven A. Ackerman and Jonathan Martin, The Chippewa Herald, 8 Oct. 2018.