welcome to The official beginning of astronomical winter, marked by the winter solstice.
The 2024 Northern Hemisphere winter solstice begins on December 21 at approximately 4:20 a.m. ET. Although this time it won’t be as dramatic as the conjunction of Jupiter and Saturn in 2020, the longest night of the year is still an important turning point. From now on, the days (meaning daylight hours) will gradually start to get longer again.
Curious why this happens? To better understand the winter solstice and the relationship between Earth and the Sun, WIRED spoke with Tans Tans, a former postdoctoral fellow on MIT’s Transiting Exoplanet Survey Satellite (TESS). We spoke to Mr. Dylan.
To imagine what’s happening in space during the winter solstice, first picture a giant glass globe surrounding the Earth. Let’s ignore the rotation of the planets (which complicates everything). “If we look at the three-dimensional sphere around us, known as the celestial sphere, the sun and all other objects in the solar system move through a plane within this sphere known as the ecliptic plane,” Dr. Daylan said. ”.
“While doing so, the sun changes its declination,” he says. Right ascension and right ascension are the two principal axes of the celestial sphere. “In this frame of reference, the sun is at its southernmost position at the winter solstice from our perspective in the Northern Hemisphere.”
The winter solstice in the Northern Hemisphere occurs when the North Pole is tilted farthest from the Sun. The Arctic Circle is plunged into darkness and experiences the longest night of the year. In the Southern Hemisphere, the summer solstice occurs at the same time as the South Pole tilts toward the sun and the polar sun enters the Antarctic Circle.
NASA’s online “Basics of Spaceflight” tutorial includes an illustrated section on the celestial spheres for those who want to explore this idea more deeply.
During the winter solstice, the sun is lower in the sky, causing an unusually long midday shadow. The summer solstice is important to humans, but it has little meaning to the macrocosm.
“The summer solstice is defined with respect to the Earth-Sun system, and not necessarily with respect to the solar system as a whole. The sun is very sacred to us, and its position on the celestial sphere as a function of time throughout the year. We give the sun a lot of meaning because it’s so important,” Daylan says. “It determines the climate. It tells us throughout the year when crops will mature. So this is very important, especially for historical civilizations.”
It’s time to celebrate
From Japan’s yuzu baths to Peru’s Inti Raymi celebrations, cultures around the world have a long history of celebrating the winter solstice. Modern druids and archaeologists in Britain continue to focus on the Stonehenge monument during this period. While the two groups’ interests may sometimes coincide, they often disagree over issues such as the display of human remains found at Stonehenge.
Below you can watch a livestream of the sunrise broadcast from Stonehenge on YouTube during the winter solstice.
