moment when the Earth’s exis is at its most extreme tilt in relation to the sun, and the sun is at either its highest or its lowest position in the sky, causing the duration of either day or night to be at its longest; happens twice a year, in the northern hemisphere on ~ June 20 (summer solstice, when the sun is at its highest and day at its longest) and ~ December 21 (winter solstice, when the sun is at its lowest and day is shortest); Latin sol = sun + status = standing still