It is spherical, however, it is not a perfect ball. Due to rotation, the planet is slightly flattened at the poles; such a figure is usually called a spheroid or geoid - “like the earth.”
The earth is huge, its size is difficult to imagine. The main parameters of our planet are as follows:
- Diameter - 12570 km
- Length of the equator - 40076 km
- The length of any meridian is 40008 km
- The total surface area of the Earth is 510 million km2
- Radius of the poles - 6357 km
- Equator radius - 6378 km
The earth simultaneously rotates around the sun and around its own axis.
The earth rotates around an inclined axis from west to east. Half of the globe is illuminated by the sun, it is day there at that time, the other half is in the shadow, there it is night. Due to the rotation of the Earth, the cycle of day and night occurs. The Earth makes one revolution around its axis in 24 hours - a day.
Due to rotation, moving currents (rivers, winds) are deflected to the right in the northern hemisphere, and to the left in the southern hemisphere.
Rotation of the Earth around the Sun
The Earth rotates around the sun in a circular orbit, completing a full revolution in 1 year. The earth's axis is not vertical, it is inclined at an angle of 66.5° to the orbit, this angle remains constant during the entire rotation. The main consequence of this rotation is the change of seasons.
Let's consider extreme points rotation of the Earth around the Sun.
- December 22- winter solstice. The southern tropic is closest to the sun (the sun is at its zenith) at this moment - therefore, it is summer in the southern hemisphere, and winter in the northern hemisphere. Nights in the southern hemisphere are short; on December 22, in the southern polar circle, the day lasts 24 hours, night does not come. In the northern hemisphere, everything is the other way around; in the Arctic Circle, the night lasts 24 hours.
- 22nd of June- day of the summer solstice. The northern tropic is closest to the sun; it is summer in the northern hemisphere and winter in the southern hemisphere. In the southern polar circle, night lasts 24 hours, but in the northern circle there is no night at all.
- March 21, September 23- days of the spring and autumn equinoxes The equator is closest to the sun; day is equal to night in both hemispheres.
The Earth is constantly in motion, rotating around the Sun and around its own axis. This movement and the constant tilt of the Earth's axis (23.5°) determines many of the effects that we observe as normal phenomena: night and day (due to the rotation of the Earth on its axis), the change of seasons (due to the tilt of the Earth's axis), and different climate in various areas. Globes can be rotated and their axis is tilted like the Earth’s axis (23.5°), so with the help of a globe you can trace the movement of the Earth around its axis quite accurately, and with the help of the Earth-Sun system you can trace the movement of the Earth around the Sun.
Rotation of the Earth around its axis
The Earth rotates on its own axis from west to east (counterclockwise when viewed from the North Pole). It takes the Earth 23 hours, 56 minutes, and 4.09 seconds to complete one full rotation on its own axis. Day and night are caused by the rotation of the Earth. Angular velocity The Earth's rotation around its axis, or the angle through which any point on the Earth's surface rotates, is the same. It is 15 degrees in one hour. But the linear speed of rotation anywhere at the equator is approximately 1,669 kilometers per hour (464 m/s), decreasing to zero at the poles. For example, the rotation speed at latitude 30° is 1445 km/h (400 m/s).
We do not notice the rotation of the Earth for the simple reason that in parallel and simultaneously with us all objects around us move at the same speed and there are no “relative” movements of objects around us. If, for example, a ship moves uniformly, without acceleration or braking, through the sea in calm weather without waves on the surface of the water, we will not feel at all how such a ship is moving if we are in a cabin without a porthole, since all objects inside the cabin will be move parallel with us and the ship.
Movement of the Earth around the Sun
While the Earth rotates on its own axis, it also rotates around the Sun from west to east counterclockwise when viewed from the north pole. It takes the Earth one sidereal year (about 365.2564 days) to complete one full revolution around the Sun. The path of the Earth around the Sun is called the Earth's orbit and this orbit is not perfectly round. The average distance from the Earth to the Sun is approximately 150 million kilometers, and this distance varies up to 5 million kilometers, forming a small oval orbit (ellipse). The point in the Earth's orbit closest to the Sun is called Perihelion. The earth passes this point in early January. The point of the Earth's orbit farthest from the Sun is called Aphelion. The earth passes this point in early July.
Since our Earth moves around the Sun along an elliptical path, the speed along the orbit changes. In July, the speed is minimal (29.27 km/sec) and after passing aphelion (upper red dot in the animation) it begins to accelerate, and in January the speed is maximum (30.27 km/sec) and begins to slow down after passing perihelion (lower red dot ).
While the Earth makes one revolution around the Sun, it covers a distance equal to 942 million kilometers in 365 days, 6 hours, 9 minutes and 9.5 seconds, that is, we rush along with the Earth around the Sun at an average speed of 30 km per second (or 107,460 km per hour), and at the same time the Earth rotates around its own axis once every 24 hours (365 times per year).
In fact, if we consider the movement of the Earth more scrupulously, it is much more complex, since the Earth is influenced by various factors: the rotation of the Moon around the Earth, the attraction of other planets and stars.
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Type: jpg Date: 2015-11-16
Have you ever wondered how fast the Earth rotates around its axis and how we manage to walk steadily on the Earth, despite the fact that its rotation speed is still not small? Let's start with the fact that the Earth has a gravitational force, which keeps us on it, and the huge inertia of the Earth does not allow us to feel rotation! This article will help us find out what the speed of the Earth is around its axis, and will also tell us how fast the Earth rotates around the Sun.
When we talk about the speed of the Earth, we must keep in mind that speed is a relative quantity and is therefore always measured in comparison to another relative object. This means that movement can only be measured when there is a reference point. For example, the Earth's speed can only be calculated relative to its own axis, the Milky Way, the Solar System, surrounding astronomical objects, or the Sun. Therefore, to find out, for example, the speed of rotation of the Earth around the Sun, you have to use special Astronomical Units. It takes the Earth one year or 365 days to complete one revolution around the Sun. In its orbit around the Sun, the Earth travels 150 million km. Therefore, the Earth rotates around the Sun at a speed of approximately 30 km/sec.
The Earth makes a complete revolution around its axis in 23 hours 56 minutes and 04.09053 seconds, this time is approximately taken for the length of a day - 24 hours. The Earth's axis is an imaginary line that passes through the center of the Earth, the North and South Poles. To understand how fast the Earth rotates, we must figure out how fast the Earth rotates at the equator. To do this, we need to know the circumference of the Earth at the equator, which is 40,070 km. Now simply dividing the circumference of the equator by the length of the day, we get the speed of rotation of the earth around its axis:
40070 km/ 24 hours = 1674.66 km/h
The value of 1674.66 km/h is the answer to the question at what speed the Earth rotates around its axis at the equator. However, this speed cannot be considered as a constant, since the speed of rotation in different places is different. The speed varies depending on the location of a point on the earth’s surface, that is, at what distance this point is from the equator. The thing is that at the equator the circumference of the Earth is greatest, and, therefore, being at the equator, you, together with the earth’s surface, travel the greatest distance around the Earth’s axis in 24 hours. However, approaching the North Pole, the circumference of the earth's surface decreases, and you and the Earth travel less distance in 24 hours.
In an ideal case, the rotation speed at the North and South Poles drops to zero! Thus, the speed of rotation of the Earth around its axis depends on the latitudinal location of the place. The speed is highest at the equator, then it decreases as you approach the North or South Pole. For example, the Earth's rotation speed in Alaska is only 570 km per hour! In middle latitudes, the rotation speed reaches its average value. For example, in places like New York and Europe, the Earth's rotation speed is approximately 1125 -1450 km/h.
We hope that you are now more aware of the issue of how fast the Earth rotates on its own axis. To calculate the circumference of the earth in the place where you are, you just need to determine the cosine of the angle of your latitude, which, as you know, is given in angles, just take a closer look at the map. Then you need to multiply this value by the circumference of the Earth at the equator to get the circumference at your latitude. Dividing the circumference by 24 (the number of hours in a day) you will get the speed of the Earth's rotation around its axis in the place where you are.
What is an orbit? How long does it take for the Earth to complete one revolution around the Sun? How is the earth's axis positioned relative to the orbital plane?
1. Annual movement of the Earth. Like other planets, the Earth rotates in its orbit along a closed circle around the Sun. But the Earth’s orbit is not a regular circle, but a slightly elongated circle. Therefore, the Earth comes close to the Sun once a year (January 3), and once departs to the farthest point of its orbit (July 5). The difference in distance between the closest (147 million km) and the farthest (152 million km) points is only 5 million km. This is a very small value compared to the average distance from the Earth to the Sun.
The Earth completes its orbit around the Sun in 365 days and 6 hours. It is generally accepted that there are 365 days in a year. The remaining 6 hours add up to 24 hours or one day over 4 years, which are added every 4 years to February. Then 3 years consist of 365 days, and the fourth year consists of 366 days. A year consisting of 366 days is called " leap year" February in such a year consists of 29 days, and in the remaining 3 years - of 28 days.
2. Differences in heat distribution on the Earth's surface. The amount of heat entering the Earth from the Sun directly depends on the position of the Earth's axis to the orbital plane. If the earth's axis was perpendicular to the orbital plane, then throughout the entire territory day would be equal to night throughout the year. Therefore, there would be no change of seasons. We would know neither summer, nor winter, nor spring, nor autumn. In the equatorial zone it would be hot summer all the time, in the middle zones it would be autumn or spring, closer to the poles there would be frosty winters all year round.
In this regard, the natural belts and zones of the Earth would also be located differently than they are now.
Instead of dense forests North America and Eurasia would be covered with evergreen tundra. And the polar sides would be covered by an eternal shield of snow and ice.
But since the earth's axis is not perpendicular to the orbital plane, but at an angle of 66.5°, solar heat is distributed differently on the earth's surface. The tilt of the earth's axis does not change when moving around the sun. Therefore, at any point on Earth, the angle of incidence of the sun's rays and the duration of the fall are constantly changing throughout the year. As a result, the amount of incoming heat changes and the seasons change.
In May-August, the Earth is directed towards the Sun by the northern hemisphere (Fig. 10), and more heat and light arrive on this side of the planet. Therefore, in the northern hemisphere it is summer, and in the southern hemisphere, on the contrary, it is winter.
Rice. 10. Change of seasons depending on the location of the Earth in orbit.
In December-February, the Earth appears on the opposite side. Now the Sun heats up the southern hemisphere more, it is summer there, and winter in the northern hemisphere.
In September-November, March-May, the globe is turned sideways to the Sun, light and heat are distributed to both hemispheres. On one hemisphere it is spring, on the other it is autumn.
1. Why does the Earth approach the Sun once and move away once during the year?
2. How long does it take for the Earth to make one revolution around the Sun?
3. Why does February sometimes have 28 days and sometimes 29 days?
4. Why do the seasons change?
5. Which months correspond to winter, spring, summer and autumn in your area? 6. In what cases would there be no change of seasons?
7. It’s autumn in your area. What time of year is it at this latitude in the southern hemisphere?
8. Draw a diagram of the location of the Earth in orbit in winter, summer, spring, autumn in your area.
Questions and tasks to summarize the section “Earth - planet” solar system»
1. What celestial bodies are part of the solar system?
2. What is the significance of the location of the Earth in the solar system?
3. Why are there no conditions for life on other planets besides Earth?
4. Why are asteroids called minor planets?
5. Why did ancient people consider the Earth first flat, then disk-shaped?
6. What evidence is there about the spherical shape of the Earth? Name everything in full. Which ones have you observed yourself?
7. Why don’t we notice the spherical shape of the Earth?
8. What effect does the spherical shape of the Earth have on the distribution of heat?
9. What is the significance of the length of day and night for life on Earth?
10. What would happen on the Earth if it did not rotate around its axis?
11. At what age do people born on February 29 celebrate their first birthday, and why?
12. Why and how do seasons change on Earth?
The fifth largest planet in the solar system, Earth, formed 4.54 billion years ago from protoplanetary dust and gas, has the shape of an irregular ball and not only rotates around the Sun in an orbit in the form of a faint ellipse with an average speed of approximately 100 thousand km/ hour, but also around its own axis. Rotation occurs, when viewed from the North Pole, in the direction from west to east, or in other words, counterclockwise. Precisely because the Earth rotates around the Sun and at the same time around its own axis, absolutely in all parts of this planet there is a periodic change of day and night, as well as a sequential change of the four seasons.
The average distance from the Sun to the Earth is approximately 150 million km, and the difference between the smallest and greatest distance, is equal to approximately 4.8 million km, while the earth’s orbit changes its eccentricity very slightly, and the cycle is 94 thousand years. An important factor influencing the Earth's climate is the distance between it and the Sun. There are suggestions that the ice age on Earth began precisely at a time when it was at the maximum possible distance from the Sun.
"Extra" day on the calendar
The Earth makes one revolution around its own axis in approximately 23 hours 56 minutes, and one revolution around the Sun occurs in 365 days and 6 hours. This difference in periods gradually accumulates and once every 4 years an extra day appears in our calendar (February 29), and such a year is called a leap year. Also on this process The Moon, located in close proximity, has a certain effect, under the influence of which the Earth’s rotation gradually slows down, and this in turn lengthens the day by about one thousandth every 100 years.
Significant climate change is coming
The change of seasons occurs due to the tilt of the Earth's axis of rotation to the orbit of the Sun. This angle is now 66° 33′. The attraction of other satellites and planets does not change the angle of inclination of the Earth's axis, but forces the Earth to move in a circular cone - this process is called precession. At the moment the position of the Earth's axis is such that North Pole is opposite the North Star. Over the next 12 thousand years, the earth's axis will shift due to the influence of precession, and will be opposite the star Vega, which is only half the way ( full cycle precession is 25,800 years), and will cause very significant climate changes across absolutely the entire surface of the Earth.
Fluctuations causing Earth's climate to change
Twice a month when passing over the equator and twice a year when the Sun is in the same position, the attraction of precession decreases and becomes equal to zero, after which it increases again, i.e. the rate of precession is oscillatory in nature. These fluctuations are called nutation; they reach their maximum value on average once every 18.6 years and, in terms of their influence on climate, take second place after the change of seasons.
Briefly in the rotation of the Earth around the Sun.
