Why do night and day alternate? How is it scientifically explained?

It is because our earth is rotating, and the sunlight received during the rotation is uneven, and there are places where the sun is not exposed.

In fact, it is because of the change of the sun, because the sun will move to the northern hemisphere for a while, and then to the southern hemisphere, so it will alternate.

The reason for the alternation is that the sun needs to rotate, and the sun also needs to rest, in which case the sun, moon and stars are created.

Summary. Because the earth is rotating.

Why does day and night alternate?

Because the earth is rotating.

The phenomenon of alternating between day and night is produced with the rotation of the earth, because the earth is a non-luminous sphere, so the sunlight can only illuminate half of the earth's surface at the same time, and because the earth is constantly rotating, the illuminated area will change with the movement of the earth, when half is day, the other side must be night, so there is a phenomenon of day and night alternating with each other.

The phenomenon of alternating day and night is formed by the interaction between the Earth's rotation and its rotational motion.

Earth's rotation refers to the time it takes for the Earth to rotate around its own axis. This has led to the constant generation of day and night changes on the earth. When the Earth rotates, the Sun's Gwangju Dan line hits a part of the Earth, leaving it in a bright daylight state.

The other part of the earth is facing away from the sun, with no direct illumination, and is in a dark state of night.

The revolution of the earth refers to the time it takes for the earth to make one revolution around the sun. The Earth's orbit is elliptical, so the distance between the Earth and the Sun is constantly changing. As the Earth moves along its orbit, the position of the Sun's rays hitting the Earth also changes.

This results in different lengths of day and night depending on the season.

Because of the influence of the earth's rotation and revolution, there is a normal alternation between day and night. When the sun rises, it indicates the beginning of a new day and the beginning of the day; And when the sun sets, it signifies the end of the day and the beginning of night. In the Western Hemisphere, the process is reversed.

Possible effects of the alternation of day and night:

1. Biological activities: Many animals and plants have physiological mechanisms that adapt to diurnal changes. Daytime is the time of activity for many creatures, as they search for food, reproduce, and engage in other survival activities.

At night, some animals hunt, forage for food, or avoid predators. Of course, there are many animals that are active at night, mainly depending on the biological characteristics.

2. Temperature change: The alternation of day and night also causes temperature changes. When the sun rises, the surface of the earth begins to be heated by sunlight, and the temperature gradually increases.

As the sun sets, the surface begins to lose its sunlight radiation, and the temperature gradually drops. This temperature change has a great impact on the climate and seasonal changes on the planet.

The above content reference: Encyclopedia - day and night alternation.

Here's how the alternation of day and night came about:

The alternation of day and night is a natural phenomenon. The earth is a non-luminous and opaque sphere, and the sunlight can only illuminate half of the globe at the same moment, and the half of the globe illuminated by sunlight is day, and the half of the globe that is not illuminated by sunlight is the dividing line (circle) between the night, day hemisphere and the night hemisphere, which is called the morning and dusk line (circle).

Expand your knowledge:

At any given moment, the diurnal state of the various parts of the Earth can be expressed in terms of the height of the sun. Sun altitude is short for solar altitude angle, which indicates the inclination of the sun's rays to the local ground plane. Everywhere in the day hemisphere, the height of the Sun is always greater than 0 degrees, that is, the Sun is above the horizon; Everywhere along the morning and dusk lines, the height of the sun is equal to 2 degrees, that is, the sun is just above the horizon; Everywhere in the night hemisphere, the height of the Sun is always less than 0 degrees, that is, the Sun is below the horizon.

Because the earth is constantly moving, day and night are constantly alternating. The cycle of day and night, or the diurnal variation of the height of the sun, is 24 hours and is called a solar day. The solar day restricts human daily life and rest, so it is used as the basic unit of time.

In addition, the short duration of the solar day prevents the entire Earth's surface from heating and cooling too violently, thus ensuring the survival and development of living organisms on Earth.

Due to the rotation of the earth, the day and night conditions at the same time are different at different positions of the earth, some are noon, some are midnight, and some are experiencing the alternation of day and night in the morning, dawn or evening. When the sun rises to its highest position of the day, it shines only on the meridian of that place, which is the local noon. The time thus determined is called local time.

For every 15 degrees of longitude, local time differs by 1 hour.

Since the Earth's axis is tilted, the length of day and night varies in different parts of the Earth. In the north and south poles of the earth, the sun shines obliquely all year round, and the length of day and night decay varies the most. In the high latitudes of the northern and southern hemispheres, there will also be a phenomenon that the sun does not set or does not rise all day long, that is, it is day or night 24 hours a day, which is the phenomenon of "polar day" and "polar night" in the polar region.

At the North and South Poles, there are polar days and nights that last for half a year.

The discovery of the phenomenon of day-night depends on the heliocentric theory of Nicolaus Copernicus (1473 1543): the earth revolves around the sun and rotates at the same time, which is a reasonable explanation for the phenomenon of day-night cycle. 300 years after the heliocentric theory was proposed, a scientist named Foucault (Jean-Bernard-Lon (1819 1868) discovered the law of the movement of the pendulum, which provided strong evidence for heliocentrism.

The alternation of day and night is caused by the rotation of the Earth and the Earth's revolution around the Sun.

Earth's rotation refers to the rotational motion of the earth around its own axis. The Earth is tilted on an axis approximately perpendicular to the ecliptic plane, and this axis is called the Earth's axis. When the Earth's axis is tilted, the various regions of the Earth face the Sun at different times, so there will be variations in insolation and night.

The Earth's revolution around the Sun means that the Earth orbits around the Sun in an elliptical orbit. The time it takes for the earth to go around the sun is about days, forming a year. However, due to the elliptical shape of the Earth-to-air bridge ball orbit, the distance between the Earth and the Sun will vary slightly, but this has no direct effect on the alternation of day and night.

As the Earth rotates, a certain part of the Earth is constantly approaching the Sun, experiencing only sunrise, daytime, and sunset; On the other side of the earth, it is away from the sun and experiences night. This leads to the alternation of day and night.

Different regions of the planet experience different lengths of time for day and night. In the Northern Hemisphere of the Earth, when the Northern Hemisphere is tilted towards the Sun, some parts of the Northern Hemisphere experience longer days and shorter nights, which is summer. And when the Northern Hemisphere is far from the sun, some regions experience longer nights and shorter days, which is winter.

The situation in the southern hemisphere is the opposite.

Therefore, the rotation and revolution of the earth and the tilt of the earth's axis are the main causes of the alternation of day and night.

The earth will rotate, the moon revolves around the earth, in most places on the earth, there is always a time when the moon covers the sun, this time is night, the moon is not shining is the light emitted by blocking the sun, when the moon no longer blocks the sun this state is day, the period of the earth's rotation is 24h, so it will be closed to the phenomenon of alternating day and night.