Anywhere on earth there is a time when it is light and a time when it is dark. This is due primarily to our main luminary - the Sun. It moves across the sky, changing the level of illumination. Simply put, it gets dark at night because the sun goes below the horizon.
Interesting point of view of ancient people
In ancient times, people assumed that the Sun was spinning around our planet and hiding behind the horizon. No one for a long time could even imagine that it was our planet that rotates in the vast outer space around the star. The same goes for the Moon. The sun and moon were given a divine origin: they were worshiped, brought gifts, praised in songs and rituals. But the era of science has come, which has proved that everything happens just the opposite. Planet Earth is not the center of the universe, but just a tiny part of it, and why it is dark at night has nothing to do with any divine manifestations.
What is the rotation of the Earth and what does it affect
There are two simultaneous movements and movements of the planet in space: movement in orbit around the Sun, as well as around its own axis, like a child's top. That is, at the same time, when the planet flies in outer space, it revolves around itself, and the combination of these factors is the reason why it is dark at night and light during the day. Moving along an orbit in space, along with the fact that the Earth's axis is inclined to this very orbit at an angle of about 66 degrees, is the reason for the change of seasons and their "dissimilarity".
In different parts of the Earth, depending on the degree of heating by the rays of the luminary, autumn, winter, spring and summer change in due time. So, middle latitudes are most often visited by all four seasons, in varying degrees of their intensity (for example, in Italy, summer, like winter, is much warmer than in Moscow). At the Equator, which is mostly under direct sunlight close to 90 degrees at noon, the day lasts partly a little longer than 12 hours.
Poles: why is it cold, even though it's been there for half a year?
At the poles, the picture is very special - the sun's rays fall in such a way that they glide and are almost completely reflected from the surface, without lingering and leaving no heat in it, although day and night here last almost half a year each. Why the north and south poles are the coldest regions of our planet.
Different length of day and night
The rotation of the planetaround the Sun, the main star for us, sets the change of seasons, as well as the change of day and night. The spherical shape of the planet, the heterogeneity of the surface and the ability of light rays to reflect complement and diversify the climate in regions similar in location. But there are days when a day begins in all latitudes up to the polar zone, having the same distribution of time between the clear part of the day and the dark part - the days of the spring and autumn equinoxes. At this time, at the equator, any object will give the smallest shadow, because the sun sends its rays at an angle of 90 degrees to its surface.
In principle, with the question of why it is dark at night, everything is clear. But what is interesting is that it is dark for a long time, and sometimes a little. Our Northern Hemisphere is characterized by a decrease in the duration of the night from March 21 (spring equinox) to September 23 (autumn equinox), and vice versa - long nights are observed in winter. In the southern hemisphere, the opposite is true.
How to explain this to children?
Explaining to children the phenomenon that it is dark at night because the sun does not shine is not quite right. After all, the sun is always shining. It does not turn on and off by someone else's decision, like a table lamp. But there is no need to talk about the position of the Earth in space, about the angles of incidence of rays and other abstruseness that can be understood already by school children. To do this, it is best for parents to be smart and demonstrate clearly how this happens. In order to explain why it is dark at night, you need to familiarize the child with two concepts: what is the Sun andwhat is planet earth. It is quite simple to do this: draw two balls, one is yellow and with rays (the Sun itself), and the other is blue with a similar outline of the mainland. Further, without going into complex terminology, talk about the form, and clearly demonstrate using a model of the solar system. A yellow balloon and a small globe will be enough, and if possible, it is better to buy a full-fledged model or make one yourself, and even with your child.
Show that the sun is standing still, and we are spinning, which is why its rays do not always fall on different parts of the globe. Then the child will understand that it is dark at night, because at this time we turn away from him, turn our backs to the sun, so to speak. For complete clarity, you can demonstrate this phenomenon in the dark using the same globe and a flashlight acting as the Sun.
