Winter Solstice 2024: When Is the Shortest Day of the Year?

The winter solstice is a celestial milestone, marking the shortest day and longest night of the year. In 2024, the winter solstice occurs on Saturday, December 21 at 4:20 a.m. ET in the Northern Hemisphere. This moment is more than just an astronomical event—it's a turning point in our annual journey around the sun.

Why Is the Winter Solstice the Shortest Day of the Year?

The Earth's axis is tilted at an angle of 23.4 degrees, and this tilt is responsible for the changing length of daylight throughout the year. During summer in the Northern Hemisphere, the North Pole is tilted towards the Sun, resulting in longer days. In winter, however, the North Pole is tilted away, causing shorter daylight hours. At the winter solstice, the sun appears at its lowest point in the sky, leading to the fewest hours of daylight for the year.

For instance, New York will have just 9 hours and 15 seconds of sunlight, while Los Angeles, being farther south, will enjoy slightly more at 9 hours and 53 minutes, according to Time and Date. This phenomenon occurs because the Earth's tilt determines how much sunlight different parts of the globe receive. On December 21, the tilt reaches its maximum angle away from the sun in the Northern Hemisphere, giving us the shortest day and longest night. Interestingly, the shortest day of the year doesn't necessarily correspond with the earliest sunset. For example, sunset on December 8 in New York was at 4:28 p.m. ET, but on the solstice, it will be four minutes later, at 4:32 p.m. ET. "The latest sunrise and earliest sunset do not coincide due to the tilt of the Earth's rotational axis and the Earth's elliptical (not circular) orbit around the Sun," Darren Baskill, a physics and astronomy lecturer at the University of Sussex, told Newsweek.

Is the Winter Solstice Always on the Same Day?

Not quite. While the winter solstice usually falls on December 21 or 22, it can occasionally occur on December 20 or 23. These variations happen because of the Earth's elliptical orbit around the Sun and the way we measure time through the Gregorian calendar. The rarest winter solstice dates are December 20 and 23. For example, the last December 23 solstice was in 1903, and the next won't occur until 2303. A December 20 solstice is also rare, with the next one expected in 2080.

Why Is It Called the Winter Solstice?

The word solstice comes from the Latin term solstitium, meaning "Sun stands still." This name reflects the apparent pause in the sun's movement across the sky before it changes direction. Around the winter solstice, the sun seems to rise and set at the same point on the horizon for a few days before it begins to climb higher again, heralding longer days. In the Northern Hemisphere, it's called the winter solstice because it coincides with the start of astronomical winter. However, for those in the Southern Hemisphere, December 21 is the summer solstice, marking the longest day of the year.

A Seasonal Stargazing Opportunity

The winter solstice is a great time to admire the night sky by nature of its long, dark night. "As we orbit around the solar system, we get to admire different parts of the night sky at different times of the year," Baskill said. "In the summer months we get a great view of the centre of our galaxy, and in the winter months we get a great view of the other half of the sky—including the constellation of Orion and the stunning star-forming gas clouds that fill that part of the sky." Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the winter solstice? Let us know via science@newsweek.com.