Winter Solstice on december 21th
On Sunday, December 21, 2025 at 4:03 PM (French time), happens the winter solstice in the Northern hemisphere and the summer solstice in the Southern hemisphere.
That day, for 2025, the Sun is in the constellation of Sagittarius, in front of the top of the bow, above the arrowhead.
At noon, it is about 21° high above the horizon in the Hautes-Alpes, and about 17° in Paris.
At the same time, it passes at the zenith in the tropic of Capricorn, so named because 2000 years ago, it was in this constellation at this time of the year.
Solstices are not related to the distance between the Earth and the Sun : the Earth reaches its perihelion at the beginning of January. They are related to the inclination of the axis of rotation of the Earth.
Since prehistoric times, humanity has connected rituals to the winter solstice :
- The opening of the tombs of Clava cairns, a Bronze Age cemetery (~2000 BC) in Scotland, faces the direction of the setting sun of the winter solstice.
- The Celts used to burn the "yule log" which was supposed to provide heat and light for twelve days.
- The Romans celebrated Saturnalia. In 274, Emperor Aurelian made 25 December, then officially considered the day of the winter solstice, a religious festival, the "day of the birth of the Unconquered Sun" (dies natalis Solis Invicti).
- The Chinese celebrate Dongzhi (extreme of winter), and the return of positive energy flows.
January 3, a busy day for the planet Earth and in its sky :
- at 11:03, the Moon begins 2026 as it finished 2025, in Super Moon. It will still be quite round when it rises at the very beginning of night.
The term Super Moon is used when it is closest to the Earth in its orbit. The distance from the Earth to the Moon varies between 356,410 km at perigee and 405,500 km at apogee : on January 3 at 11:03 AM, the Moon is 368,037 km from Earth, 10,000 km further than the Super Moon of December 5, 2025.
- At 17:16, the Earth is at the perihelion of its rotation around the sun, which is the closest point to the Sun in its orbit, at 147,098,74 km (0.98 AU – astronomical unit). Indeed, its orbit describes an ellipse, not a circle, around the sun.
This is the time of year when the orbital speed of the Earth around the Sun is the greatest : 30,287 km/s (109 033 km/h).
The solar energy received by the Earth at perihelion is about 6% more than that received at aphelion (the most distant point from the Sun on the orbit).
On January 10th at 9:34, Jupiter is in opposition : the Sun, Earth and Jupiter are aligned.
Jupiter is opposite of the sun in the terrestrial sky. It shines all night (with a magnitude of -2.7) in the constellation Gemini, just below Castor and Pollux.
The shortest distance between Earth and Jupiter (for this opposition) occurs the day before, on January 9, with 633 million kilometers, which is a little more than 4 times the distance from Earth to the Sun.