The term "solstice" originates from the Latin words "sol" meaning "sun" and "sistere" meaning "to stand still." In Latin, "solstice" refers to the event when the sun appears to reach its highest or lowest point in the sky relative to the celestial equator. The summer solstice marks the longest day of the year, where the sun appears at its highest point in the northern hemisphere, and the winter solstice marks the shortest day, when the sun appears at its lowest point.