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What Does the Word Solstice Mean?

Earth's polar axis is tilted at 23 1/2 degrees relative to its orbital plane, and every year, each pole reaches its point of maximum exposure to the sun at the beginning of summer in that hemisphere. At each of these points -- called solstices -- winter begins in the hemisphere facing away from the sun.

The Sun Stands Still
- The word solstice comes from the two Latin words "sol" -- or sun -- and the past participle stem of the verb "sistere," which means "to stop." It signifies that the sun, which has been rising or falling steadily in elevation as spring or summer progresses, stops at the moment that the pole faces completely toward or away from the sun. It then begins to move in the opposite direction until it stops again at the opposite solstice.
Solstices and Equinoxes
- Each year, Earth passes two points in its orbit at which the poles are equidistant from the sun. These points are the equinoxes, and they signify the beginning of spring and autumn in each hemisphere. When the sun reaches the summer solstice, the day reaches its maximum length, and it's at its shortest at the winter solstice. The days and night are of approximately equal length at the equinoxes.

Astronomy