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Why Does Earth’s Tilt Change Daylight Hours Throughout the Year?
为什么一年里白昼长度会变化
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Earth orbits the Sun while tilting at about 23.5 degrees on its axis.
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This tilt stays pointed in the same direction as Earth travels around the Sun.
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When the North Pole tilts toward the Sun, days grow longer in the Northern Hemisphere.
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During that time, the South Pole tilts away, causing shorter days and winter there.
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The equinoxes occur when neither pole tilts toward the Sun, making day and night nearly equal.
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Solstices mark the longest and shortest days when tilt is most extreme toward or away.
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This consistent motion explains why summer has more daylight than winter at mid-latitudes.
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Seasonal changes in daylight also affect plant growth, animal behavior, and human energy use.
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Without axial tilt, every place on Earth would have almost the same day length year-round.
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Astronomers use these patterns to calibrate calendars and predict climate-related seasonal shifts.