1. The Earth's Tilt Is the Reason Daylight Changes
Earth orbits the Sun while tilted on its axis. It spins on its axis while tilted slightly [1]. Think of a spinning top that leans to one side instead of standing upright. The Earth is similar to that leaning top. However, unlike a toy top that spins quickly on its axis, the Earth keeps this tilt constant as it takes one year to make one large circle around the sun [1].
This tilt means the Northern Hemisphere faces more toward the Sun at some times of year and more away from it at others. When a hemisphere is tilted toward the Sun, it is summer there; when it is tilted away, it is winter. [1]. This simple tilt is the reason our seasons and day lengths change.
2. The Summer and Winter Solstices Are the Longest and Shortest Days
During the year, the day with the most daylight is called the summer solstice, and the day with the least daylight is called the winter solstice [2]. In Tokyo, the daylight lasts for about 14 hours and 35 minutes on the summer solstice. On the winter solstice, there are only about 9 hours and 45 minutes of daylight [2].
The difference between these two days is approximately 4 hours and 50 minutes [2]. This large gap shows how much the sun's path changes across the year due to the Earth's tilt.
3. On the Spring and Autumn Equinoxes, Day Is Slightly Longer Than Night
People often think that on the spring equinox and autumn equinox, day and night are exactly the same length. However, in reality, the day is slightly longer than the night [3]. In Tokyo, one study found that on the spring equinox, daylight lasted about 16 minutes longer than nighttime [3].
This happens because the air bends light, and because sunrise and sunset are counted from the top edge of the sun, not its center [3]. So, even when we think day and night are equal, the daylight lasts a bit longer.
4. A Snake-Shaped Shadow Appears on a Mayan Pyramid at Chichen Itza
At the ruins of Chichen Itza in Mexico, there is a large pyramid. It is said that in the evenings around the spring and autumn equinoxes, a shadow pattern that looks like a snake appears on the steps of this pyramid [4].
Each of the pyramid’s four sides has 91 steps When you add the top step, the total is 365 steps. This number is thought to be related to the number of days in a year [4].
5. Stonehenge Is Built to Match the Sun's Path
It was not only the Maya who carved the sun's movement into stone. The ruins known as Stonehenge in England are also built so that on the morning of the summer solstice, the sun rises near a stone standing outside the circle, called the Heel Stone [5].
The sunlight shines straight toward the center of the ruins. The main part of this site is believed to have been built more than 4,400 years ago [5].
6. Egyptian Temples Let Sunlight Reach a Special Spot Twice a Year
While Stonehenge recorded the sun's movement by the direction of the stones, there are temples in Egypt designed to deliver light itself to a specific spot. Deep inside the Abu Simbel temple, there are statues of the king. Usually, the room is dark, but only twice a year, the morning sun shines all the way in and lights up the statues [6].
These two times are believed to correspond to the king's birthday and the day he became king [6]. The architects aligned the temple so that sunlight would reach the statues on those dates.
7. Watch Where the Sun Sets to See the Change Yourself
If you want to explore this further, with an adult, note where the Sun sets this evening. Six months later, you should be able to notice how much the sunset location has shifted.