Voice of Emirates – Astronomical calculations reveal that Earth will experience the winter solstice tomorrow, Sunday, December 21, 2025. The sun will reach its southernmost point, directly above the Tropic of Capricorn. This event marks the official beginning of winter in the Northern Hemisphere, a season that will last for 89 days. Meanwhile, the summer solstice will begin in the Southern Hemisphere.
Mechanics of the chapters: Axis tilt, not distance
This phenomenon occurs due to the Earth’s axis being tilted at 23.5 degrees as it revolves around the sun. Contrary to popular belief, the seasons are not caused by the distance between the Earth and the sun. Rather, they result from the alternation of positions of the northern and southern hemispheres in receiving sunlight. Tomorrow, the North Pole will be tilted away from the sun, causing it to appear at its southernmost point in the sky. This results in the shortest day and longest night of the year for those living north of the equator.
The winter solstice: proof of the Earth’s spherical shape
Astronomers have confirmed that the winter solstice provides conclusive practical evidence of the Earth’s spherical shape, through several observations: The variation in day and night lengths: The periodic variation in daylight hours and the angle of incidence of sunlight between the northern and southern hemispheres. This variation can only occur astronomically in a spherical model.
Polar regions: On this day, the sun does not rise fully in areas north of the Arctic Circle, while it does not set at the South Pole, which confirms the curvature of the Earth’s surface.
Shadow length: The shadow of a person or object will reach its “longest” length for the entire year at noon tomorrow. This is due to the low arc of the sun’s path across the sky.
The journey back to moderation
After the sun reaches its southernmost point, it appears to rise from a fixed point for a few days. This is why it is called the solstice or the sun’s position at rest. Afterward, the sun’s path gradually begins to move northward again. With this movement, the days gradually lengthen at the expense of the nights, until the hours are exactly equal at the spring equinox, scheduled for March 20th.
Residents of the northern hemisphere will notice a later dawn tomorrow, with the sun rising from its southernmost point in the southeast. An early sunset will mark the end of the shortest day of 2025.
