solsticios

Solsticios, in Spanish, designate the two annual moments when the Sun reaches its greatest declination relative to the celestial equator. In English these events are called the solstices. The term derives from Latin solstitium, from sol meaning sun and -stitium from stare, meaning to stand still, referring to the apparent pause of the Sun’s movement at noon as it reaches its northernmost or southernmost extreme.

There are two solstices each year: the summer solstice and the winter solstice. In the Northern Hemisphere the summer solstice, around June 20–22, yields the longest day of the year, while the winter solstice, around December 20–23, yields the shortest. In the Southern Hemisphere the seasons are opposite, so the summer solstice falls around December 20–23 and the winter solstice around June 20–22. The Sun’s declination reaches about +23.44 degrees at the summer solstice and −23.44 degrees at the winter solstice. The dates can shift slightly due to the eccentricity of Earth's orbit and leap-year adjustments.

Solstices have been used in calendars and agricultural rites across cultures and continue to be observed in various cultural and religious contexts. They also serve as reference points in solar astronomy and help mark seasonal change, alongside the equinoxes, which denote days of roughly equal length.