December solstice
The Sun reaches its southernmost declination of the year. This marks astronomical summer in the south and winter in the north.
Plan the observation
2026-12-21 through 2026-12-21 · UTC calendar window · dates only, not contact times
Compare local noon solar altitude and the duration of daylight with a June night using the timeline.
Where to look
The season depends on hemisphere. This is a global orbital milestone, not a flash or momentary sky display.
Primary reference · US Naval Observatory · Reviewed 2026-11-03
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