Why at night it is dark: the rotation of the Earth around its axis and the Sun
Earth - a planet making turns around the solar body. It also makes movement around its own axis. These twists and turns are not fully investigated. Despite the difficulties of determining the rotation, scientists were able to establish why it is dark at night.
From Earth, it seems that worlds revolve around us. If you get up at the same time every day at the same time, you can see how the stars are moving across the sky, how the sun passes through it. At such moments, it seems that our planet is the center of the universe.
Around the sun
As already mentioned, the Earth always rotates around the brightest star of our solar system, and at the same time rotations occur around its own axis.
The planet revolves around the star in three hundred and sixty-five days and six hours. To make it easier to count dates, a calendar year was entered, equal to 365 days.And once every four years, when twenty-four from six hours has accumulated, one more day is added. This year was named “leap year”, and the new day is added to February.
When the Earth rotates around the star, the seasons change. Due to the fact that the planet has a certain angle of inclination - sixty-six and a half degrees, it moves in outer space. Because of the inclined position, sunlight illuminates one or the other side of the planet. When in the western hemisphere day, in the eastern night.
When the rays of the Sun fall at right angles on the planet, the days of equinox are observed - day and night have the same length. Such an event happens twice a year: on the days of the spring (in March) and the autumn (in September) equinoxes. The beginning of summer and winter are the dates when the sun shines on the planet from the highest altitude (in June and December).
Appeal of the Earth's axis to the Sun
At the days of the summer solstice, the earth's axis is turned to the sun by the north pole. At this moment at noon, the rays fall on the surface of the planet, namely - parallel to 23 degreesnorth latitude. These days most of the day at all latitudes north of the equatorial line and up to the 66th parallel is illuminated: the night becomes shorter and the days are longer.
The border of the light is a parallel of 66 s. sh.From this point begins in the northern part of the polar day. At the same time throughout the territory south of the equatorial line and up to 66 south. sh. the day is short and the night is long. Outside the southern part of the polar night comes.
At the time of the winter solstice, the earth's axis turns toward the luminary with its southern end. And, accordingly, the sun's rays fall on the southern latitudes. From this day on the parallels to the south of the equator the days are long and the nights are short. On the southern polar circle, the polar day begins to rule.
In all parts north of the equatorial line the days are shorter than the night, and in the northern Arctic Circle there is a deep night.
The polar circles are the boundaries of the polar day and night, which last from one to 178 days. For the entire time of the polar night the sun sets over the horizon. During the polar day the sun shines and does not hide behind the horizon.
Rotation around you
The earth revolves around itself, making a complete revolution in a day. The planet rotates from east to west, so the sun rises in the east and sets in the west.
Turns of the planet around them allow us to understand why it is dark at night and the sun is hiding behind the horizon. It is the appearance of the Sun and its lowering that causes the change of day and night.
So why is it dark at night, and where is the light at this time? One part of the planet is constantly facing the sun. And on that part of it, where the sun's rays fall, there is a day. On the opposite (dark side), to which the light is not enough, there is night. During the rotation, the sunlight gradually penetrates those areas that were dark until this point, and from those where it was light, the Sun leaves. From Earth, this phenomenon is observed in the form of sunset and dawn.
The rotation of the planet around itself, during which it alternately alternates between different areas of sunlight, counts the Earth day and changes the day to night. At a time when the sun does not shine on the western part of the planet, it illuminates the eastern. Based on this, in the first part will be the night, and the other - the day. That is why it is dark at night.
Rotation around the galaxy
Earth is located in the solar system, which is located in the Milky Way galaxy. It received its name for its special appearance: in the night sky, it looks like spilled milk. In fact, the white bar is a cluster of millions of stars.
The galaxy has a spiral shape. According to modern calculations, our solar system is closer to the edge of the galaxy, in one of its sleeves. It spirals around the center of the galaxy.According to estimates, the Milky Way makes a complete rotation around the center in about 225 million years.
Scientists on galactic rotation
Scientists believe that this rotation around the center of the galaxy should somehow affect our existence and all the planets of the solar system. However, data about what kind of events entail full momentum, yet. This is due to the small age of mankind, it is estimated only tens of thousands of years, and scientists make serious observations of the cosmos and the phenomena occurring in it only for a few centuries.
The earth moves with our solar system around the center of our galaxy. One complete turnaround takes about 225 million years. At the same time, the Earth always revolves around our star. Moreover, during the rotation of the planet is then removed, then approaching it. Because of this phenomenon, people are watching the change of seasons. During rotation around a star, the Earth at the same time turns around its axis from west to east: because of this phenomenon, day is replaced by night.