Definition: The solstice occurs twice in each circuit of the earth around the sun. A circuit of the sun is how we define a year, so there are two solstices a year, winter and summer. The winter solstice is in late December and the summer solstice in late June in the Northern Hemisphere. In the Southern Hemispheres, the solstices are reversed. The word solstice is formed from two Latin words; one for sun sol and one for stand sistere. The summer solstice is when the sun appears to be at its greatest and the day is at its longest. The winter solstice is when there is the least amount of sun. The other two seasons, fall and spring, are marked by the equinoxes when day and night are roughly equal.
Examples:Around the winter solstice, when the nights are longest, many cultures have celebrations featuring lights, like Saturnalia, Hanukkah, and Christmas. The Summer solstice has less of a sense of urgency, but there are also celebrations for it.