Geography of the Earth's equator
World map with the equator line
We can assume that our planet has the shape of a ball with an average radius of 6371.3 km. But this representation is not entirely correct and is not always suitable for accurate calculations. If we take scientific concepts and numbers, then the Earth is not a perfect sphere; in the world of experts, its shape is described by the concepts of geoid or ellipsoid.
The imperfection of the shape of our home planet was discovered back in the 17th century by Isaac Newton and Christiaan Huygens.
Due to rotation around its axis and the resulting centrifugal force, which reaches a peak at the equator and zero at the poles, the planet rather has the shape of an oblate ball. Because of this, the polar radius is 21.38 km less than the equatorial radius. Interesting fact : the Congo River, flowing in Central Africa, is the deepest and second longest on the continent.
But the most interesting thing about it is that it is the only river in the world that crosses the equator twice. The planet reaches its highest rotation speed at zero latitude. This fact can easily be explained by the maximum radius of the Earth precisely at the equator. So the length of the equator is 40,075
km
, and if this number is divided by 24 hours (the time during which the planet makes one revolution), then you can find out the speed of rotation of the Earth at zero latitude. Thus, at the equator it is approximately 1670 km/h. The closer to the poles, the lower the speed.
Core structure and characteristics
The path to knowledge is long and thorny, but its fruits are sweet. Today, the following physical characteristics of the Earth’s core are reliably known:
The temperature of the Earth's core at the central point can reach up to 6000 degrees Celsius - this is the same as on the surface of the Sun! But unlike the luminary, the energy of the depths is fed not by nuclear reactions, but by gravity. More precisely, its compression - the pressure in the core exceeds atmospheric pressure by 3.5 million times, reaching 360 gigapascals. Although atomic decay processes occur in the depths of the Earth, their contribution is not so large. And even without enormous compression, they would be sluggish and not so productive.
Classical basic spheres of the Earth
- The Earth's core reaches 7,000 kilometers in diameter - it's larger not only than the Moon, but also Mars
! It does not take up much space inside our planet - about 15% of the volume - but its mass of 1,932 × 1024 kilograms is 30% of the total mass of the Earth. - It turns out that different layers of the core rotate in different directions. Today it is believed that the outer liquid core rotates around its axis from east to west, and the inner one - from west to east, and is also faster than the Earth. However, the difference is not very significant - in a year it is ahead of the planet by only a quarter of a degree
In addition, the latest research suggests that inside the inner core of the Earth lies another one - the “most” inner core, which rotates on a completely different axis. Let's look at it and other components of the earth's core in more detail.
Outer core
The very first layer of the core that is in direct contact with the mantle is the outer core. Its upper boundary is located at a depth of 2.3 thousand kilometers below sea level, and the lower boundary is at a depth of 2900 kilometers. In composition, it is no different from the underlying shells - the gravitational pressure is simply not enough for the hot metal to harden. But its liquid state is the Earth’s main trump card in comparison with other inner planets of the solar system.
How does geodynamo work?
The fact is that it is the liquid part of the core that is responsible for the emergence of the Earth’s
. As the reader probably knows, the magnetosphere serves as the planet’s shield against charged particles from outer space and the solar wind. They are even more dangerous than radiation - particles can damage not only living organisms, but also electronics. Biologists believe that it was the active magnetic field that became the key to the survival of primitive single-celled creatures.
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How exactly is a magnetic field generated? It is generated by the rotation of liquid iron and nickel in the core. The magnetic properties of metals have nothing to do with it - this is an exclusively dynamic effect. And the outer core heats the mantle - and in some places so much that the ascending flows of magma even reach the surface, causing volcanic eruptions.
Inner core
Inside the liquid shell is the inner core. This is the solid core of the Earth, whose diameter is 1220 kilometers - the same size as Charon
, companion moon
of Pluto
. This part of the core is very dense - the average concentration of the substance reaches 12.8-13 g/cm3, which is twice the density of iron, and hot - the heat reaches the famous 5-6 thousand degrees Celsius.
High pressure at the center of the Earth causes the metal to solidify at temperatures above its boiling point. In this case, unusual crystals are formed that are stable even under normal conditions. It is believed that the inner core is a forest of many kilometers of iron and nickel crystals, which are directed from south to north. In order to test this theory, Japanese scientists spent ten years creating a special diamond anvil - only in it can one achieve the same pressure and temperature as in the center of our planet.
"Inner" inner core, or hypothetical nesting doll
Even during the initial studies of the core using seismic waves, geologists noticed an unusual deviation of vibrations within the core in the direction from east to west.
Since, due to its rotation, the Earth is wider at the equator than at the poles, this was not noticed at first. But subsequent study revealed that the central part of the core may be just another shell
What is the "inner" inner core? Most likely, it consists of the same metal crystals - but directed not to the north, but to the west. It is not yet clear what causes this separation. However, the orientation of the crystals indicates that there were gravitational interactions with the Sun or Moon.
"Inner" inner core in the structure of the Earth
Equator, longitude and latitude
Equator, longitude and latitude
The designation of the equator as latitude is by definition equal to 0°. The equator is one of the five most important latitudes for navigation, which are generally accepted in the geographical community. Four others:
- Arctic Circle;
- Southern Arctic Circle;
- Tropic of Cancer;
- Tropic of Capricorn.
Zero latitude can be considered the only line that falls within the definition of a great circle.
A great circle, in turn, is any circle passing along the surface of the ball, dividing it at the center. So the equator line runs through the center of the planet, dividing it into two equal halves. Other latitudes cannot be called a great circle, because, due to their proximity to the poles, they do not divide the circle into equal parts.
Parallels, in turn, can be called large circles, since each of them fits the definition. But it is worth considering that the Earth has the shape of an ellipsoid, so the length of any parallel is less than the equator, and accordingly the halves are smaller.
Interesting fact : in Brazil there is a city called Macapa. He is in two hemispheres at the same time. In the city center there is a football stadium named Estadio Milton Correa. The center field line of this stadium runs almost exactly along the equator. Not far from the sports facility there is a monument to “Marco Zero”.
Areas along the equator experience the shortest sunrises and sunsets. This is due to the fact that the Sun's daily path is almost perpendicular to the horizon for most of the year. The length of daylight hours (from sunrise to sunset) is almost constant throughout the year; it is about 14 minutes longer than night time due to atmospheric refraction (the bending of the sun's rays) and the fact that sunrise is counted from the moment the top, not the center, of the sun's disk touches the horizon.
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