Solstices and equinoxes explain the broad seasonal pattern behind sunrise, sunset and day length. Select dates near these turning points to see how the pattern appears at your chosen location.
Solar results
Solstices mark the seasonal daylight extremes
At the June solstice, the Sun reaches its northernmost annual position relative to Earth’s equator. The December solstice marks its southernmost position. These events correspond broadly to the longest and shortest daylight periods in each hemisphere, with opposite seasons north and south.
Use the actual local day-length results when examining a specific place. Near the equator the annual variation is small; at high latitudes, continuous daylight or darkness can extend across many dates. A solstice is an astronomical event, not a promise that only one calendar date has a uniquely rounded daylight value.
Equinoxes do not guarantee exactly 12 hours of daylight
At an equinox, the Sun crosses the celestial equator. The familiar description of equal day and night simplifies how sunrise and sunset are defined. The visible Sun has a disk, and atmospheric refraction affects the apparent horizon event.
As a result, the measured sunrise-to-sunset interval is usually a little longer than 12 hours on an equinox. The nearby date when that interval is closest to 12 hours is sometimes called the equilux. Its timing depends on latitude and the convention used, rather than being one worldwide date.
Why earliest sunrise and latest sunset have different dates
The solstice concerns the amount of daylight. Sunrise and sunset clock times also depend on when solar noon falls on the civil clock. The seasonal shift in that solar-noon time can move the morning and evening extremes away from the longest or shortest day.
Use the earliest and latest sunrise and sunset guide to compare these separate quantities. The annual graph gives a broad view, while the monthly table helps inspect individual dates.
Compare the same location and time convention
Choose one location and compare dates on either side of the event. Read daylight duration for the seasonal change; read sunrise and sunset separately for the morning or evening schedule. A daylight-saving adjustment can obscure the smooth physical trend if you look only at clock times.
This page does not calculate the exact global instant of a solstice or equinox. It explains local daylight around those events. For the distinction between the equinox and equal measured day and night, see the U.S. Naval Observatory’s explanation.
Frequently asked questions
Is the summer solstice always the hottest day?
No. The solstice concerns solar geometry and daylight. Temperature depends on heat storage, weather and local climate, so the warmest part of the year commonly follows the maximum-daylight period.
Are the solstice dates the same calendar date everywhere?
The astronomical event is one instant worldwide, but different time zones can place that instant on different local calendar dates. Its calendar date also varies across years.
Does the Sun rise exactly due east on an equinox?
It rises close to east in many locations, but an exact visible bearing depends on the event definition and observing conditions. Use the calculated direction for the selected place and date rather than assuming precisely 90°.
What is the difference between equinox and equilux?
Equinox describes the Sun crossing the celestial equator. Equilux refers to a local date with approximately equal measured daytime and nighttime. The latter depends on latitude and the sunrise/sunset definition.