Zonnewende

Zonnewende, a Dutch term meaning the turning of the Sun, refers to the two annual turning points in the Sun’s apparent path across the sky, which produce the longest and shortest days of the year. The word combines zon (sun) and wende (turning point). In practice, zonnewende can denote either the zomerzonnewende (summer solstice) or the winterzonnewende (winter solstice).

The zomerzonnewende occurs around June 20–21 in the Northern Hemisphere and marks the Sun’s maximum declination, about +23.44 degrees. On this day, the Sun reaches its highest point in the sky at solar noon and the local day is the longest of the year. After the solstice, daylight gradually shortens.

The winterzonnewende occurs around December 20–23 and corresponds to the Sun’s minimum declination, about −23.44 degrees. It yields the shortest day, with the Sun at its lowest solar altitude at noon. Following the solstice, daylight length lengthens again.

Astronomical context: the solstices result from the tilt of the Earth's axis, currently about 23.44 degrees relative to its orbit around the Sun. The solstice does not mark the exact start of summer or winter in all regions, but rather the extreme positions of the Sun’s declination. At high latitudes, the solstices relate to phenomena such as the midnight sun or polar night.

Cultural significance: across many cultures, solstices have been observed with calendars, rituals, and monuments. Archaeological sites such as Stonehenge and Newgrange are noted for alignments with solstitial sunrise or sunset, reflecting long-standing attention to these solar turning points in human history.