What is the winter solstice? Celebrations, Science, Livestream

Welcome to the official beginning of astronomical winterwhich is marked by the winter solstice.

In 2024, the winter solstice for the northern hemisphere begins December 21 around 4:20 am EST. While this time it won’t be as dramatic as 2020 conjunction of Jupiter and Saturnthe longest night of the year remains a significant turning point. As you move forward, the days (ie the hours of the day) gradually begin to get longer.

Curious why this happens? WIRED spoke with Tansu Daylana former postdoctoral associate at Transiting Exoplanet Survey Satellite (TESS) at MIT, to better understand the winter solstice and our planet’s relationship with the sun.

To imagine what happens in space during a winter solstice, start thinking of a giant glass ball that surrounds the Earth, and ignore the rotation of the planet (which complicates everything). Daylan says, “If you look at the three-dimensional sphere around us, known as the celestial sphere, the sun and all the other objects in the solar system move through a plane in this celestial sphere, known as the plane of the ecliptic”.

“Meanwhile, the sun changes its declination,” he says. Declension and straight ascent they are the two primary axes of the celestial sphere. “In this frame of reference, the sun is at its southernmost point when it’s the winter solstice from our perspective in the northern hemisphere.”

A winter solstice in the northern hemisphere happens when the north pole it is tilted the farthest from the sun. The Arctic Circle is shrouded in darkness and experiences its longest night of the year. In the southern hemisphere, a summer solstice occurs simultaneously with the south pole angled toward the sun and the Antarctic Circle. midnight sun.

NASA’s Basics of Space Flight online tutorial includes a section on the celestial sphere with illustrations for anyone who wants to explore the idea further.

The low position of the sun during a winter solstice will cause your midday shadow to be exceptionally long. Although important to humans, a solstice does not have much meaning in terms of the larger cosmos.

“The solstices are defined in terms of the Earth-sun system, not necessarily the entire solar system. We attach a lot of meaning because the sun is so sacred to us, and its location on the celestial sphere, depending on the time in year-round, it’s very important,” says Daylan. “It sets the climate. Throughout the year, it tells us when crops ripen. So it is very important, especially for historical civilizations.”

Time to celebrate

From the yuzu baths in Japan at the Sunday celebrations in Peru, the cultures of the world have a long history of celebrating the winter solstice. Druids and contemporary archaeologists in the UK continue to look at the Stonehenge monument at this time of year. The interests of the two groups align on occasion, but they often disagree on issues such as the display of human remains found at Stonehenge.

Below, during the winter solstice, you can watch a livestream of the sunrise on YouTube from Stonehenge.