"Natural Science 4" is an interactive encyclopedia that includes scientific information in the understanding of fourth grade students, wonderfully illustrated and animated.
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* Chapter 3 Lesson 18 *
* Movements of the Earth. The day-night cycle. The seasons *
Every morning the sun delights us when it appears in the sky and we enjoy its presence all day, until it sets. In reality, it shines 24 hours a day. When the Sun shines on one side of the Earth, the other is plunged into darkness.
The day-night alternation is caused by the Earth's rotation around its axis. Since our planet is spherical, half of its surface is illuminated by the Sun and the other half is not.
Viewed from the North Pole, our planet rotates counterclockwise. A solar day, i.e. 24 hours, is the time required for the Earth to rotate once on its axis so that the Sun appears in the same place in the sky the next day. However, the Earth also moves around the Sun, and this movement makes measuring the day somewhat complicated. The actual time of one rotation of the Earth is slightly shorter at 23 hours and 56 minutes.
Although a solar day is 24 hours long, not every day has 12 hours of light and 12 hours of darkness. The day is shorter in winter than in summer. This is because the Earth's imaginary axis is tilted. As the Earth moves around the Sun, its northern half is tilted toward the Sun in summer, making the day longer than the night. In winter, this makes the night longer. In spring and autumn, the inclination is neither toward nor against the Sun, so day and night are close in duration.
Also due to the tilt of the Earth's axis, at the North Pole the sun rises on March 21 and sets on September 21, so that the day lasts half a year, and the night, the same. Of course, the same thing happens at the South Pole, only the dates change.
What do you think are the advantages of living in the polar regions? What about the downsides?