Solstice

From the combination of sol (sun) and sistere (cause to stand or stop) the solstice marks the highest or lowest points of the sun’s path in the sky each year.

In summer, for instance, the sun’s arc in the sky stops its daily ascent at the longest day of the year. There it reverses, beginning its descent to the autumnal equinox — with equal day and night — and eventually to its lowest point at the year’s shortest day, the winter solstice. At that point, its descent finished, the sun once again begins its slow climb towards the summer solstice.

Also see:

• Equinox
• Seasons