Winter Solstice – Equinox: The Science Behind The Terms
No matter if temperatures will drop incessantly for weeks, winter won’t officially begin until Saturday. Here are some secrets about the winter solstice, the astronomical start to the snowy season and the shortest day of the year.
Explaining Winter Solstice
The winter solstice connotes the beginning of astronomical winter. It’s not the same as the beginning of meteorological winter, which is based on a 12-month calendar.
To answer this question factually, let’s take a leaf from middle school science class. The Earth rotates in dual movements: one, it moves in a big circle around the sun. Two, it spins around an axis like a top, creating day and night. That axis has a slight tilt, causing the Northern and Southern hemispheres to receive varying amounts of sunlight at different times of the year.
The general view about the winter solstice is that it’s a day-long event. However, the term refers to the precise instance at which one-half of the Earth—either the top or the bottom—tilts furthest away from the sun, leading to the fewest hours of sunlight of the year for that half of the hemisphere.
Although the winter solstice marks the shortest day of each year, it also prompts a progression in the amount of sunlight each day for the following six months. Same way, the day when the Earth’s tilt is closest to the sun is described as the summer solstice. It’s the longest day of the year and refers to the astronomical beginning of summer.
Occurrence of Winter Solstice
In the Northern Hemisphere, winter solstice occurs on Dec. 21 or 22. In 2024, it will fall on Dec. 21. The summer solstice will occur after six months, around June 21.
For people living below the equator, however, those days are reversed. Their winter solstice is a June event, while their summer solstice comes in December.
The Meaning of Equinoxes
There are two equinoxes in a year — one in the spring, and one in the fall. During the equinoxes, the sun positions itself right at the crown of the Earth’s equator. In plain words, there are equal amounts of sunlight and darkness on those two days.
The vernal equinox, occurring in March in the Northern Hemisphere, marks the astrological culmination of winter. In September, the autumnal equinox marks the astrological culmination of summer.
Astrological Season Changes
Read below the different astronomical season changes you can expect to see following Saturday’s winter solstice:
- Vernal Equinox (Spring): Thursday, March 20, 2025, 5:01 a.m.
- Summer Solstice (Summer): Friday, June 20, 2025, 10:42 p.m.
- Autumnal Equinox (Fall): Monday, Sept. 22, 2025, 2:19 p.m.
Viewing Winter Solstice
Yes! in a way. Each day, the sun maps a course across the sky, rising in the east and setting in the west. As the winter solstice approaches and the number of hours sunlight remains in a day decreases; the sun’s orbit sinks lower in the sky, although it follows the same arc.
When the winter solstice arrives, the sun is sitting at the lowest possible position in the sky. Due to that, the shadow you cast becomes longer and longer while the winter solstice converges. Thus, while solstices aren’t practically as visible as eclipses, when you go outside in the afternoon in the winter solstice, your shadow will be the longest it will year around.