Show the equator line on the world map. What are the dimensions of planet earth? Why was the designation of the equator introduced?

The equator is an imaginary circular line that encircles the entire globe and passes through the center of the Earth.

The equator line is perpendicular to the axis of rotation of our planet and is located at an equal distance from both poles.

Equator: what is it and why is it needed?

So, the equator is an imaginary line. Why did serious scientists need to imagine some lines outlining the Earth? Then, the equator, like meridians, parallels and other dividers of the planet, which exist only in the imagination and on paper, make it possible to make calculations, navigate in the sea, on land and in the air, determine the location of various objects, etc.

The equator divides the Earth into the Northern and Southern Hemispheres and serves as the origin of geographic latitude: the latitude of the equator is 0 degrees. It helps to navigate the planet's climate zones. The equatorial part of the Earth receives the largest amount of sunlight. Accordingly, the further the territories are located from the equatorial line and the closer they are to the poles, the less sun they receive.

The equatorial region is an eternal summer, where the air is always hot and very humid due to constant evaporation. At the equator, day is always equal to night. The sun is at its zenith - it shines vertically downwards - only at the equator and only twice a year (on those days on which the equinoxes occur in most geographic zones of the Earth).

The equator passes through 14 countries. Cities located directly on the line: Macapa (Brazil), Quito (Ecuador), Nakuru and Kisumu (Kenya), Pontinac (Kalimanta island, Indonesia), Mbandaka (Republic of the Congo), Kampala (capital of Uganda).

Equator length

The equator is the longest parallel to the Earth. Its length is 40.075 km. The first who was able to approximately calculate the extent of the equator was Eratosthenes, an ancient Greek astronomer and mathematician. To do this, he measured the time during which the sun's rays reached the bottom of a deep well. This helped him calculate the length of the radius of the Earth and, accordingly, the equator thanks to the formula for circumference.

It should be noted that the Earth is not a perfect circle, so its radius differs slightly in different parts. For example, the radius at the equator is 6378.25 km, and the radius at the poles is 6356.86 km. Therefore, to solve problems of calculating the length of the equator, the radius is taken equal to 6371 km.

The length of the equator is one of the key metric characteristics of our planet. It is used for calculations not only in geography and geodesy, but in astronomy and astrology.

Everyone knows that planet Earth has a round shape. But few people can say what size the planet is. What is the circumference of the earth along the equatorial line or along the meridian? What is the diameter of the Earth? We will try to answer these questions in as much detail as possible.

First of all, let's look at the basic concepts, which we will encounter when answering the question about the circumference of the Earth.

What is the equator called? This is a circular line encircling the planet and passing through its center. The equator is perpendicular to the earth's axis of rotation. It is equally distant from one and the other pole. The equator divides the planet into two hemispheres called the Northern and Southern. It plays a big role in determining the climate zones on the planet. The closer to the equator, the hotter the climate, because these areas receive more sunlight.

What are meridians? These are the lines that divide the entire globe. There are 360 of them, that is, each fraction between them is equal to one degree. Meridians run through the poles of the planet. Meridians are used to calculate geographic longitude. The countdown starts from the prime meridian, which is also called the Greenwich meridian, since it runs through the Greenwich Observatory in England. Longitude is called eastern or western, depending on the direction in which the count is taken.

Ancient times

The circumference of the Earth was first measured in Ancient Greece. It was the mathematician Eratosthenes from the city of Siena. At that time it was already known that the planet has a spherical shape. Eratosthenes observed the Sun and noticed that the luminary at the same time of day, when observed from Syene, was located exactly at the zenith, but in Alexandria it had a deviation angle.

These measurements were made by Eratosthenes on the summer solstice. The scientist measured the angle and found that its value was 1/50 of the whole circle, equal to 360 degrees. Knowing the chord of an angle of one degree, it needs to be multiplied by 360. Then Eratosthenes took the interval between two cities (Siena and Alexandria) as the length of the chord, assumed that they were on the same meridian, made calculations and named the figure 252 thousand stadia. This number meant the circumference of the Earth.

For that time, such measurements were considered accurate, because there were no ways to measure the circumference of the Earth more accurately. Modern scientists admit that the value calculated by Eratosthenes turned out to be quite accurate, despite the fact that:

these two cities - Siena and Alexandria are not located on the same meridian;
the ancient scientist obtained the figure based on the days of travel of camels, but they did not walk in a perfectly straight line;
it is unknown what instrument the scientist used to measure angles;
it is not clear what the stage used by Eratosthenes was equal to.

However, scientists still maintain an opinion about the accuracy and uniqueness of the method of Eratosthenes, who first measured the diameter of the Earth.

In the Middle Ages

In the 17th century, a Dutch scientist named Sibelius invented a method for calculating distances using theodolites. These are special instruments for measuring angles, used in geodesy. Sibelius's method was called triangulation; it consisted of constructing triangles and measuring their bases.

Triangulation is still practiced today. Scientists have conventionally divided the entire surface of the globe into triangular areas.

Russian studies

Scientists from Russia in the 19th century also contributed to the issue of measuring the length of the equator. The research was carried out at the Pulkovo Observatory. The process was led by V. I Struve.

If earlier the Earth was considered a ball of an ideal shape, then later facts accumulated according to which the force of gravity decreased from the equator to the poles. Scientists have tried to explain this phenomenon. There were several theories. The most popular of them was considered the theory about the compression of the Earth from both poles.

To test the validity of the hypothesis, the French Academy organized expeditions in 1735 and 1736. As a result, scientists measured the length of the equatorial and polar degrees at two points on the globe - in Peru and Lapland. It turned out that at the equator the degree has a shorter length. Thus, it was found that the polar circumference of the Earth is 21.4 kilometers smaller than the equator circumference.

Nowadays, after error-free and accurate research, it has been established that the circumference of the Earth at the equator is 40075.7 km, and along the meridian - 40008.55 km.

It is also known that:

The semimajor axis of the Earth (the radius of the planet at the equator) is 6378245 meters;
the polar radius, that is, the semiminor axis, is 6356863 meters.

Scientists have calculated the surface area of the Earth and determined the figure of 510 million square meters. km. Land occupies 29% of this area. The volume of the blue planet is 1083 billion cubic meters. km. The mass of the planet is determined by the figure 6x10^21 tons. The share of water in this value is 7%.

Video

Since the stars are in space are too far from the Earth, using the parallax effect, you can, knowing the distance between the observation points D (base) and the displacement angle α in radians, determine the distance to the object:

for small angles:

parallax effect: (a displacement or difference in the apparent position of an object is considered from two different viewing points), the only reason for the change in the measured angle of the north star is the curvature of the Earth's circumference.

The angular diameter of the Moon and the Sun is almost the same: 0.5 degrees.

Our ancient astronomers/ Priests, priests / could measure the position of the northern star with an accuracy of 1 degree. Using such an angle measuring instrument (astrolabe), calibrated in degrees, he could obtain fairly accurate results (perhaps with a 0.25% degree of accuracy).

If one of our astronomers made this measurement from a location at point (A) near Giza (30 0 C), the star Mizar should have appeared about 41 degrees above the local horizon. If a second astronomer were located 120 nautical miles south of *point (A) (*measured in ancient units of length, of course), he would have noticed that the same object (star) had an altitude of 39 degrees (2 degrees lower than than the height measured at the location).

Equator length

The length of the equator is one of the key metric characteristics of our planet. It is used for calculations not only in geography and geodesy, but in astronomy and astrology.

We all live on the beautiful planet Earth, about which humanity has already learned a lot, but even more is still hidden from us and is waiting in the wings until man’s desire for knowledge reveals all the secrets of our world.

General information about planet Earth

Let's remember what we know about planet Earth. Earth is the only inhabited planet in our solar system, even moreover, the only one on which there is life. Earth is the third planet, counting from the Sun, before Earth there are two more planets Mercury and Venus. The Earth rotates around the Sun and the inclination of the rotation axis relative to the Sun is 23.439281°, thanks to this inclination we can observe the change of seasons throughout the year. The distance from the earth to the sun is 149,600,000 km; for a stream of light to cover the distance from the sun to the earth it needs 500 seconds or 8 minutes. Our planet also has a satellite, the Moon, which revolves around the Earth, just as the Earth revolves around the sun. The distance from the Earth to the Moon is 384,400 km. The speed of the Earth's movement in its orbit is 29.76 km/sec. The Earth makes a complete rotation on its axis in 23 hours 56 minutes and 4.09 seconds. For convenience, it is generally accepted that there are 24 hours in a day, but to compensate for the remaining time, another day is added to the calendar every 4 years and this year is called a leap year. A day is added in the month of February, which usually has 28 days; a leap year has 29 days. There are 365 days in a year and 366 days in a leap year, this is a complete cycle of changing seasons (winter, spring, summer, autumn).

Earthly dimensions and parameters

Now let's move from space to planet Earth itself. In order for life to arise on the planet, there must be many factors and conditions that create a favorable habitat for countless living organisms inhabiting the Earth. In fact, the more we learn about our common home, the more clearly we understand how complex and perfect an organism the planet Earth is. There is nothing superfluous, everything has its place, and everyone has their own important role to play.

The structure of planet Earth

There are a total of 8 planets in our solar system, 4 of which belong to the terrestrial planets and 4 to the gas group. Planet Earth is the largest terrestrial planet and has the greatest mass, density, magnetic field and gravity. The structure of the Earth is not homogeneous, and it can be conditionally divided into layers (levels): the earth's crust; mantle; core.
Earth's crust – the uppermost layer of the Earth’s solid shell, it in turn is divided into three layers: 1) sedimentary layer; 2)granite layer; 3) basalt layer.
The thickness of the earth's crust can range from 5 - 75 km deep into the Earth. This range depends on the location of measurements, for example, on the ocean floor the thickness is minimal, and on continents and mountain ranges it is maximum. As we have already said, the earth's crust is divided into three parts, the basalt layer was formed first, therefore it is the lowest, followed by the granite layer, which is absent on the ocean floor, and the uppermost sedimentary layer. The sedimentary layer is constantly being formed and modified, and humans play an important role in this.
Mantle – the layer next after the earth’s crust, which is the most voluminous, about 83% of the total volume of the Earth and approximately 67% of its mass, the thickness of the mantle reaches 2900 km. The upper layer of the mantle, which is 900 km, is called magma. Magma is molten minerals, and the output of liquid magma is called lava.
Core - This is the center of planet Earth, consists mainly of iron and nickel. The radius of the earth's core is approximately 3500 km. The core is also divided into an outer core with a thickness of 2200 km, which has a liquid structure and an inner core with a radius of about 1300 km. The temperature in the center of the core is close to 10,000 °C; on the surface of the core, the temperature is significantly lower than 6,000 °C.

Shape of the Earth. Diameter of the Earth. Earth's mass. Age of the Earth.

If you ask the question, “What is the shape of the Earth?”, we will hear possible answers: round, sphere, ellipsoid, but this is not entirely true; a special term Geoid was introduced to denote the shape of the Earth. A geoid is essentially an ellipsoid of revolution. Determining the shape of the planet made it possible to accurately determine the diameters of planet Earth. Yes, it is precisely the diameters of the Earth that, due to its irregular shape, are distinguished by several:
1) the average diameter of the Earth is 12,742 km;
2) the equatorial diameter of the Earth is 12756.2 km;
3) the polar diameter of the Earth is 12713.6 km.

The circumference along the equator is 40,075.017 km, and along the meridian it is slightly less than 40,007.86 km.
The mass of the Earth is a rather relative quantity that is constantly changing. The mass of the earth is 5.97219 × 10 24 kg. The mass increases due to the settling of cosmic dust on the surface of the planet, the fall of meteorites, etc., due to which the mass of the Earth increases annually by approximately 40,000 tons. But due to the dispersion of gases into outer space, the mass of the Earth decreases by about 100,000 tons per year. Also, the loss of Earth's mass is affected by an increase in temperature on the planet, which contributes to more intense thermal movement and the leakage of gases into space. The smaller the Earth's mass becomes, the weaker its gravity and the more difficult it becomes to maintain an atmosphere around the planet.
Thanks to the radioisotope dating method, scientists were able to establish the age of the Earth; it is 4.54 billion years. The age of the Earth was more or less accurately determined back in 1956, and was subsequently slightly adjusted with the development of technology and measurement methods.

Other information about planet Earth

The Earth's surface area is 510,072,000 km², of which water spaces occupy 361,132,000 km², which is 70.8% of the Earth's surface. The land area is 148,940,000 km², which is 29.2% of the Earth's surface area. Due to the fact that water covers much more of the surface of the planet, it was more logical to name our planet Water.
The volume of the Earth is 10.8321 x 10 11 km³.
The highest point on the earth's surface above sea level is Mount Everest, whose height is 8848 m, and the deepest place in the world's oceans is considered to be the Mariana Trench, its depth is 11022 m. Well, if we give average values, then the average height of the Earth's surface above sea level is 875 m , and the average depth of the ocean is 3800 m.
The acceleration of gravity, also known as the acceleration of gravity, will be slightly different in different parts of the planet. At the equator g=9.780 m/s² and gradually increases, reaching g=9.832 m/s² at the poles. The average value of the acceleration due to gravity is taken to be g = 9.80665 m/s²
Composition of the atmosphere of planet Earth: 1) 78.08% nitrogen (N2); 2) 20.95% oxygen (O2); 3) 0.93% argon (Ar); 0.039% - carbon dioxide (CO2); 4) 1% water vapor. Other elements from Mendeleev's periodic table are also present in small quantities.
Planet Earth is so large and interesting that, despite how much we already know about the Earth, it never ceases to amaze us with the secrets and unknowns that we continue to encounter.

Like all the planets in the solar system, the Earth has a spherical shape. Before talking about its exact dimensions, let's introduce a few important geographical concepts.

The earth rotates around an imaginary straight line - the so-called earth's axis. The points of intersection of the earth's axis with the earth's surface are called poles. There are two of them: North and South. The line of intersection of the surface of the globe with a plane passing through the center of the Earth perpendicular to the earth's axis is called equator. Planes crossing the earth's surface parallel to the equatorial plane form parallels, and the planes passing through the two poles are meridians.

Due to rotation around its axis and the resulting centrifugal force, the Earth is slightly flattened at the poles and its semimajor axis (equatorial radius, rc) is almost 21.4 km greater than the distance from the center of the Earth to the poles. Such a ball flattened at the poles is called spheroid or ellipsoid of revolution.

In Russia, for geodetic and cartographic work, the ellipsoid of F.N. Krasovsky is used (named after the scientist under whose leadership the calculations were carried out). Its dimensions are:

equatorial radius - 6378.2 km,
polar radius - 6356.8,
meridian length - 40008.5 km,
equator length - 40075.7 km,
Earth's surface area is 510 million km 2.

In reality, the figure of the Earth is even more complex. It deviates from the regular shape of the spheroid due to the heterogeneous structure of the subsoil and the uneven distribution of mass. The true geometric figure of the Earth is called geoid(“earth-like”). A geoid is a figure whose surface is everywhere perpendicular to the direction of gravity, i.e. I'll plumb it.

The surface of the geoid coincides with the level surface of the World Ocean (mentally extended under the continents and islands). The rise and fall of the geoid above the spheroid is 500-100 m.

The physical surface of the Earth, complicated by mountains and depressions, does not coincide with the surface of the geoid, retreating from it by several kilometers. Gravity constantly strives to level the surface of the Earth, to bring it into line with the surface of the geoid.