Longest night of the year: What to know about the winter solstice

Get ready to embrace the darkness during the longest night of the year ‒ the winter solstice.

The solstice occurs at the same time everywhere on Earth, this year it happens Dec. 21 at 4:21 a.m. EST. For the Northern Hemisphere, it marks the astronomical start of winter because the North Pole is tilted furthest away from the sun.

This doesn't always correlate with the seasonal temperature changes, so meteorologists dub Dec. 1 as the start of winter.

During the winter solstice, the sun's rays will be directly over the Tropic of Capricorn, a line of latitude that circles the Earth in the Southern Hemisphere. In astrology, the winter solstice marks the first day of the Capricorn season.

The date of the solstice varies from year to year and can fall anywhere between Dec. 20-23, but it most often falls on the 21st.  

What's the difference between a solstice and and equinox?

Solstices occur in June and December, which mark the beginning of astronomical summer and winter, respectively. The summer solstice is when the sun is at its highest point in the sky in the Northern Hemisphere, while the winter solstice occurs when the sun is at its lowest point in the sky.

The word "solstice" came from the Latin words for "sun" and "to stand still" because the sun appears to stay in the same place on the horizon at sunrise and sunset.

Equinoxes – when day and night are roughly equal – occur in March and September and mark the astronomical beginning of autumn and spring in the Northern Hemisphere.

We observe the sun as it travels along its longest and highest course across the southern sky, reaching its northernmost point from Earth's equator. So, at local solar noon, your shadow will be the shortest of the entire year.

When will solstice and equinox occur in 2025?

◾ Vernal equinox (spring) - March 20 at 5:01 a.m. EDT

◾ Summer solstice - June 20 at 10:42 p.m. EDT

◾ Autumnal equinox (fall) - Sept. 22 at 2:19 p.m. EDT

◾ Winter solstice - Dec. 21 at 10:03 p.m. EST

SOURCE National Weather Service