Soaking up the Sun: Visualizing the Changing Patterns of Daylight in One Year

The darkest days are upon the residents of the Northern Hemisphere as daylight dwindles and the night lingers longer. Meanwhile, those in the Southern Hemisphere bask in their warmest and longest days—and those at the Equator continue to observe consistent days and nights.

These changing lengths of days and nights depend on where you are on Earth and the time of year. The tilt of the Earth’s axis and its path around the sun affect the number of daylight hours.

Today’s post highlights two simple and elegant animations that help demonstrate how different latitudes experience the sun’s light over the course of one year. The first comes from Reddit user harplass, while the second comes from data scientist Neil Kaye.

Longer and Shorter Days

The Ancient Greeks envisioned the movement of the sun as a Titan named Helios who rode across the sky in a horse-drawn chariot, illuminating the known world below. A rosy-fingered dawn would herald his imminent arrival, while the arrival of the dusk god Astraeus, ever on Helios’ heels, marked the passage of day into night.

Today, time is not at the whims of Greek mythology but by the measurable and consistent movement of celestial bodies. A day on Earth is 24 hours long, but not every day has 12 hours of daylight and 12 hours of night. The actual time of one Earth rotation is a little shorter–about 23 hours and 56 minutes.

Daytime is shorter in winter than in summer, for each hemisphere. This is because the Earth’s imaginary axis isn’t straight up and down, it is tilted 23.5 degrees. The Earth’s movement around this axis causes the change between day and night.

During summer in the Northern Hemisphere, daylight hours increase the farther north you go. The Arctic gets very little darkness at night. The seasonal changes in daylight hours are small near the Equator and more extreme close to the poles.

Length of a Rotation: Equinoxes and Solstices

There are four events that mark the passing stages of the sun, equinoxes and solstices.

The two solstices happen June 20 or 21 and December 21 or 22. These are the days when the sun’s path in the sky is the farthest north or south from the Equator. A hemisphere’s winter solstice is the shortest day of the year and the summer solstice the year’s longest.

In the Northern Hemisphere the June solstice marks the start of summer: this is when the North Pole is tilted closest to the sun, and the sun’s rays are directly overhead at the Tropic of Cancer.

The December solstice marks the start of winter when the South Pole is tilted closest to the sun, and the sun’s rays are directly overhead the Tropic of Capricorn.

The equinoxes happen around March 21 and September 23. These are the days when the sun is exactly above the Equator, which makes day and night of equal length.

Stand in the Place Where You Are

It is always darkest before the dawn, and every passing of solstice marks a time of change. As the Northern Hemisphere heads into the winter holiday season, it also marks the advent of longer days and the inevitable spring and summer.

The lengths of days and nights are constantly changing, but every one will get their time in the sun, at some point.