Today is the longest night of the year/ Here's what you need to know

2024-12-21 21:11:00, Kuriozitete CNA

The winter solstice marks the beginning of winter in the Northern Hemisphere and brings the shortest day and longest night of the year. In 2024, the solstice occurs on Saturday, December 21, at 4:21 am EST. This astronomical event, caused by the Earth's tilt of about 23.5 degrees relative to its orbit around the Sun, also marks the summer solstice in the Southern Hemisphere.

Science after the solstice

The Earth's axial tilt causes variable exposure to sunlight in different hemispheres throughout the year, creating the seasons. During the Northern Hemisphere's winter solstice, the North Pole tilts away from the Sun, plunging it into darkness for 24 hours. At the same time, the South Pole tilts towards the Sun, experiencing uninterrupted light. On this day, the Sun appears lower in the sky at northern latitudes, reaching its highest point directly above the Tropic of Capricorn (23.5° south of the equator).

Why does the date change?

The solstice usually falls on December 21 or 22 in the Northern Hemisphere. This variation comes from the slight misalignment of the Gregorian calendar with Earth's orbital period of 365.25 days, which requires leap years to synchronize the calendar.

The length of winter

Astronomically, winter lasts from the solstice to the vernal equinox (March 19-21), covering about 89 days in the Northern Hemisphere. Meteorologically, winter includes the period from December 1 to February 28/29, coinciding with the coldest months of the year.

Misconceptions about the winter cold

Despite the decrease in sunlight, the winter solstice is not the coldest day of the year. The oceans and land slowly release the heat stored in the summer, delaying the peak of cold by several weeks. As the days lengthen after the solstice, solar radiation gradually warms the Earth.

Cultural significance

The solstice has inspired cultural traditions around the world. At Stonehenge in England, the setting sun coincides with the Altar and Slaughter stones, symbolizing rebirth or veneration of the Sun. Similarly, Mayan structures such as those in Tulum, Mexico, include alignments with the solstice, testifying to ancient civilizations' deep connection to celestial patterns.

Earth's distance from the Sun

Contrary to common perception, the Earth is closest to the Sun (at perihelion) in early January, about two weeks after the solstice. At this point, Earth is about 91.4 million miles (147.1 million kilometers) from the Sun, compared to its furthest point (aphelion) in early July.

A perpetual celebration of change

From ancient monuments to modern gatherings, the winter solstice represents reflection and transition. It marks a key moment of the year, reconnecting humanity to the rhythms of the cosmos and offering hope through the lengthening of the day.