Why the Sun Reaches a Seasonal Turning Point
Earth’s axis is tilted about 23.5 degrees relative to its orbit. As Earth travels around the Sun, that tilt changes which hemisphere leans more directly toward sunlight. When a hemisphere is tilted most toward the Sun, the Sun appears highest in the sky at midday and traces its longest path across the sky. That is its summer solstice. When the hemisphere leans most away, the Sun follows its shortest daily path: the winter solstice.
The Sun is not actually stopping or reversing course. “Solstice” comes from Latin words meaning “Sun stands still,” because its noon position appears to pause briefly near its farthest point north or south before shifting back the other way.
Why the Change Is Gradual
A solstice is a turning point, not a sudden switch in the weather or in daylight. Earth keeps moving along its orbit, and the Sun’s apparent path shifts a little from day to day. Around the summer solstice, the difference in daylight between neighboring days is small; after it, days begin to shorten in that hemisphere. The opposite happens after the winter solstice.
The effect depends on location. Near the equator, daylight length changes relatively little over the year. Farther toward the poles, the contrast grows, and regions inside the polar circles can experience days when the Sun does not set—or does not rise. The solstice is therefore a single astronomical turning point, but its visible consequences range from subtle changes in sunset time to continuous daylight.
