Space Series- Planet Earth

Space Series- Planet Earth

Earth is the third planet of the solar system away from the sun after Mercury and Venus, and is the largest planet planets in the solar system, in terms of diameter and mass and density. The planet is also called the world and the land.

Earth is home to millions of species, including humans; it is the only place known to have a life in the universe. The earth was formed about 4.54 billion years ago, and life has appeared on its surface in the last billion years. Since then, the Earth’s biosphere has changed the atmosphere and the planet’s non-biological conditions, allowing the propagation of organisms that live only in the presence of oxygen. The ozone layer, which works with the Earth’s magnetic field, blocks harmful radiation, allowing life to surface Earth. The ozone layer obscures ultraviolet radiation. The Earth’s magnetic field displaces and removes charged primary particles from the sun at great speeds and distances them from outer space away from Earth, causing no harm to the living organisms.


Earth is in the constellation of the solar system, and the solar system itself is one of the hundreds of billions of stars that form the Milky Way or the Milky Way. The area that distinguishes the Earth from the Sun is a region known as a habitable range, meaning that after Earth is about 150 million kilometers away from the sun and orbits the Sun in a circular orbit that makes it suitable temperatures not too high and not too cold to match the origin of life And its continuation. In addition to the size of the Earth suitable to keep the atmosphere and the presence of water, and the presence of ozone gas in the atmosphere of the Earth protects the living from harmful ultraviolet radiation, as well as the magnetic field, which protects it from the particles of rapid origin that comes with the solar wind threaten the safety of living on the ground .

The outer surface of the earth is divided into several parts:

The hard earth crust, which reaches a depth of about fifty kilometers, the geosphere with a thickness of 4000 km, and the nucleus of the central earth solid made of iron and nickel.

The Earth’s atmosphere is in a liquid state connected to a moving electricity, resulting in the Earth’s magnetic field. The crust is floating on the molten ground.

The earth’s crust is divided into a number of great tectonic plates, which gradually appeared on Earth’s surface because of their gradual cooling over millions of years.

The relatively thin crust floats above the so-called terrestrial envelope, the large part of the Earth’s mass, consisting of very hot magma under the crust at a temperature of about 1,700 degrees Celsius and increasing its rate as it approaches the center of the iron earth.

These magmas are carried out in different parts of the earth by the crust forming what we know from the volcanoes. Water covers 71% of the Earth’s surface, salt water, and aquatic life, while the rest of the continents, islands, rivers, and freshwater are necessary for life on land in all its forms of plant and animal.

Evolution of continents on Earth

 Two main possibilities for the evolution of continents were suggested:

The first is the steady development that continues until the present era,

The second is a rapid and tentative evolution that occurred early in the history of the earth.

Research has shown that the second theory is the closest to the right. There has been a rapid and fundamental evolution of continental crusts, followed by a long-term evolution of the continental region. Measured in time, it has lasted for hundreds of millions of years. He reshaped himself continuously as continents formed, and then separated. The real estate has spilled over the surface of the earth, but it has sometimes gathered again to be a large continent. The continent of “Rodinia” one of the oldest major continents that emerged 750 million years ago, and then began its parts in the separation. Later, the continents once again formed the Panotia, between 600 and 540 million years ago, and eventually formed Panjia, whose parts had been separated 180 million years ago.

The emergence of life on earth

For almost four billion years, the energy-rich chemical interactions on Earth have produced molecules that have the capacity to multiply themselves. Nearly half a billion years later, The organism or strain from which the subsequent species evolved has evolved on the surface of the earth. Photolysis (the synthesis of chemical compounds in light) allows the energy of the sun to be directly used in life in all its forms. The oxygen produced by this process accumulates in the atmosphere, (O3) in the section Top of the atmosphere. This theory shows the origin of mitochondria and plastids (the parts of plant cells containing chlorophyll), which are subunits composed of eukaryotes (which lack the nucleus and the nuclear membrane). The fusion of small cells within large cells results in the formation of complex cells called eukaryotic cells (that is, they are characterized by a single nucleus). Real multichannel organisms formed in the form of cells within colonies take on more specific characteristics. By absorbing the ozone layer of harmful ultraviolet radiation, life has settled on the surface of the planet.

Composition and composition of the earth

Earth is a terrestrial planet, meaning it is a rocky body, not a giant gas object like Jupiter. It is also the largest of the four terrestrial planets in the solar system, in size and mass. In addition, among the four planets, the Earth has the highest densities, the highest level of gravity on its surface, the strongest magnetic field and the fastest rotation. In addition, it is the only Earth planet with active tectonics.

The shape of the planet

The shape of the planet is very close to the spherical ball shape, it is a spherical spherical body at the poles, and spurted at the equator. The result is the rotation of the planet, and it causes the Earth’s diameter at the equator to be greater than its diameter at the poles at about 43 km. The mean diameter of the reference spherical body is about 12,742 km, which is approximately 40,000 km / TT; It was originally equal to 1 / 10.000.000 from the distance from the Equator to the North Pole across Paris in France.

Clark Table of Earth – forming Oxides
CompoundThe formulaComposition
SilicaSiO 259.71%
AluminaAl 2 O 315.41%
Sodium OxideNa 2 O3.55%
Iron dioxideFeO3.52%
Potassium oxide2 O2.80%
Iron oxideFe 2 O 32.63%
Water2 O1.52%
Titanium dioxideTiO 20.60%
Phosphorus pentoxide2 O 50.22%

The chemical composition of the planet

The total mass of the planet is about 5.98 x 10 24 kg, mostly iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5% And aluminum (1.4%). The remainder, which represents 1.2%, consists of a small number of other elements. Since the heavier elements are attracted to the center, while the lighter elements are moved to the center in what is known as “interstellar” or “star redistribution”, some believe that the element of iron is the main component of the earth’s pellets, reaching 88.8% With small amounts of nickel by 5.8%, sulfur by 4.5% and less than 1% of other elements.

The internal structure of the earth

The inner part of the planet, like other planets, is divided into several layers, depending on the chemical or rheological characteristics of that matter, the matter of matter, viscosity, expansion, and lactation caused by external physical factors. Looking at the outer layer of the planet from a chemical point of view, it is a relatively thin crust of thickness of about 50 km, characterized by the formation of relatively light metals, mostly silicate.

The light crust, which contains continents, oceans, and seas, floats above the earth’s surface, which is denser than the surface material and consists of high viscosity solids. The seismic division separates the earth’s crust from the mantle beneath it, as evidenced by the time curves of the seismic waves that show a sudden increase in velocity between the earth’s crust and the earth’s crust. The thickness of the earth’s crust varies from place to place; Its average thickness under water bodies is 6 km and ranges from 30 to 50 km in continents.

Both the crust and the surface of the upper, cold and hard surface are called “rock cover” or “stone shell”, which is made up of tectonic plates.

Under the rock cover is the flow range (the upper part of the mantle under the rocky rock range and this part is so dense as to allow for rock flow), which is a relatively low viscosity layer on which the rock cover rests.

Significant changes have occurred in the crystalline structure within the mantle at 410 and 660 km below the earth’s surface, a distance that represents a transitional range separating the upper earth mantle and the lower ground mantle. Below the mantle, there is a liquid outer core with a very low viscosity above the inner steel core.

The inner core may rotate at an angular velocity higher than the rest of the planet, and its temperature increases by 0.1 to 0.5 degrees Celsius each year.

Geological layers of the earth


Component layerDensity
Gram / cm 3
35-60the upper mantle3.4.4.4
35-2890The scarf3.4.5.6
100-700 flow range
2890-5100External pulp9.9-12.2
5100-6378Internal pulp12.8-13.1

Earth temperature

The inner heat of the planet produces heat from the motion of the planets (approximately 20%) and heat from radioactive decay (approximately 80%). Potassium-40, uranium-238, uranium-235, and thorium-232 are radioactive isotopes The temperature on the planet, it is worth mentioning that the temperature in the center of the earth may exceed 7,000 thousand, and the pressure may reach 360 gigapascals. Because most of the Earth’s heat is caused by decay, scientists believe that in early periods of Earth’s history and before the short-lived isotopes were depleted, the heat produced by the Earth was much higher than it is now.

The fundamental isotopes that generate heat on the planet at present
IsotopesHeat emitted (analog volume in kg)Half-life (years)Average mean concentration of the mantle in the terrestrial mantle (the amount of peer per kilogram per kilogram of the mantle)Heat emitted (machete size in kg)
238 U9.46 × 10 -54.47 × 10 930.8 x 10 -92.91 x 10 -12
235 U5.69 × 10 -47.04 × 10 80.22 × 10 -91.25 x 10 -13
232 Th2.64 x 10 -51.40 × 10 10124 x 10 -93.27 × 10 -12
40 K2.92 x 10 -51.25 × 10 936.9 x 10 -91.08 x 10 -12

The total heat lost by the earth is estimated at 4.2 × 10 13 watts. A portion of the Earth’s geothermal energy moves towards the earth’s crust by magma rising from the earth’s mantle, a type of pregnancy consisting of high-temperature rock bursts.

The rise of magma can lead to a rise in temperature in some areas and a flow of basalt rocks on the surface.

It is worth mentioning that the earth loses its temperature through plate tectonics through the eruption of the mantle, which is accompanied by the formation of chains of mountains and hills in the middle of the oceans.

The last major factor in global warming is the transfer of thermal energy through the lithosphere, which occurs mostly in the oceans because the earth’s crust is less dense in the water bodies than on the surface of the continents.

Tectonic plates

The main panels of the earth
The name of the panelArea
10 6 square kilometers
African painting78.0
The panel of Antarctica60.9
Australia panel47.2
Eurasian painting67.8
North American painting75.9
South American Painting43.6
Pacific Plate103.3









The solid outer layer of the earth, known as the “rock cover” or “lysosphere”, is divided into parts called tectonic plates. These tectonic plates are solid parts that move with each other in three types of movements: the convergent movement; two tectonic plates move together, and the spacing moves; two of the panels move away from each other, and the slippery movement; one slips into the other Side by side.

Earthquakes, volcanoes, mountains and oceanic tides can occur along the tectonic plates and move in one of the three aforementioned movements.

The tectonic plates are based on the upper part of the flow, the part of which is solid, but the proportion of the wife is few, from the upper mantle, and it can flow and move with these tectonic plates, and the movement of these panels are strongly related to patterns Convection occurring within the mantle.

As these tectonic plates move or move on the surface of the planet, ocean bottoms occur (a process responsible for falling mass of the earth’s crust beneath others) under the main edges of these plates at close edges. At the same time, the rise of materials in the mantle at the far reaches leads to mountain chains in the middle of the oceans. The combination of these processes recycles the oceanic crust in the mantle. Through these processes together, changes in the crust of the bodies of water bodies occur constantly, making them revert to their original shape in the mantle. The oldest part of the oceanic crust is located in the western Pacific, estimated to be about 200 million years old. If compared to the oldest part of the Earth’s crust, the oldest part of it is dated to about 4030 million years ago.

Other panels on the surface of the planet include the Indian Plate, the Arabian Plate, the Caribbean Plate, and the Nazaka Plateau, located on the southern coast of Peru away from the west coast of South America, and the Acoustica Plateau, located in the South Atlantic. It is worth mentioning that the Australian slab has merged with the Indian slab since 50 or 55 million years. The plates with the oceans are the fastest moving planks; they and the cocos are moving at a rate of 75 millimeters per year, while the Pacific Plate moves at a rate of 52 to 69 millimeters per year. On the other hand, the slowest slab is the Eurasian plate; As its speed increases at a steady rate of 21 millimeters per year.

The surface of the Earth

The earth’s terrain varies greatly from place to place. For example, about 70.8% of the earth’s surface is covered with water. A large part of the continental shelf (the so-called shallow water area characterized by a gradual descent from shore to sea) at sea level. In addition, the submerged surface of the ocean’s bottoms has mountain features, including mountain ranges and hills located in the middle of the oceans, and contains volcanoes, oceanic grooves, undersea valleys, lagoons, and deep plains. The remaining 29.2% of the surface of the globe consists of mountains, deserts, plains, and other tidal features.

The surface of the planet has undergone and continues to be reshaped over the geological ages, due to tectonic and erosion factors, as well as changes to terrain on the surface of the earth being caused or corroded by tectonic plates subject to constant erosion of rain and snow Thermal cycles and chemical effects. In addition, ice and coastal erosion, coral reef chains and meteorite impacts on Earth also contribute to the remodeling of the Earth’s surface.

The continental crust consists of low-density materials such as igneous rocks such as granite and indite. There are also very little known rocks such as basalt, a highly dense volcanic rock, which is the main component of the ocean bottoms. There are also sedimentary rocks formed from sediments that pressed together. About 75% of the earth’s surface is covered with sedimentary rocks, although they make up only about 5% of the earth’s crust. The third type of rock on the surface of the earth is metamorphic rocks, formed from the transformation of other rock types by pressure or high temperatures or both. Quartz, feldspar (aluminum silicate), amphibole, mica, pyroxene, and olivine are considered the most abundant silicate minerals on earth. Carbonate minerals include calcite (found in limestone), aragonite and dolomite.

The biosphere is the last outer layer of the earth. This layer is composed of soil and is subject to the formation of the latter. This layer is found in the surface of the atmosphere, the hydrogen sphere and the biosphere. At present, arable land represents 13.31% of the planet’s total land area, providing only 4.71% of permanent crops. Approximately 40% of the land on the surface is currently being used as agricultural and pasture land, or an estimated 1.3 x 10 7 square kilometers as agricultural land and 3.4 × 10 7Square kilometers as pasture. The surface elevation of the earth varies from place to place. Some of the studies conducted in 2005 show that the lowest points are the Dead Sea (-418 m), the highest being Mount Everest (8,848 m). The average elevation of the Earth’s surface above sea level is 840 meters.

Hydrogen envelope

The availability of large amounts of carpet on the surface of the earth is one of the unique features that distinguish the “carpet planet” from other planets in the solar system. It is worth mentioning that the Earth’s carpet is mainly composed of various species, but technically, it includes all the water bodies of the world including inland seas, lakes, rivers and underground water, which are located along a length of 2,000 meters. The Challenger Valley in the Pacific Ocean, specifically the low-lying Mariana, which is 10,911.4 meters deep, is the deepest on earth. The average ocean depth is 3,800 meters, which is four times the average altitude on the continental surface.

The ocean mass is estimated at 1.35 × 10 18 metric tons or about 1/4400 of the total mass of the planet, and oceans occupy an area of 361.8 x 10 6  km 2. It should be noted that if all land on the Earth is spread evenly, the water level will reach a height of more than 2.7 kilometers.

About 3.5% of the total ocean mass consists of salt. Most of these salts were formed from volcanic activity or were extracted from volcanic cold rocks. The oceans are a reservoir of dissolved gases in the atmosphere, which is essential for the survival of many aquatic organisms. In addition, seawater has a significant impact on the global climate; it functions and the oceans as large reservoirs of heat. Changes in ocean temperature distribution are possible Can significantly affect climate change on the sea surface, such as the Southern Oscillation phenomenon known as the El Nino phenomenon.


The average atmospheric pressure on Earth is 101.325 kPa, at an altitude of 8.5 km. The atmosphere consists of 78% nitrogen and 21% oxygen, as well as trace amounts of water vapor, carbon dioxide, and other gas molecules. The height of the troposphere varies according to the latitude, ranging from 8 km at the poles to 17 km at the equator, with some variations due to weather and seasonal factors.

The presence of the planet’s biosphere has changed its atmosphere. Oxygen-based oxygenation or photosynthesis began 2.7 billion years ago, leading to the formation of the atmosphere, which consists primarily of oxygen and nitrogen.

This change has led to the proliferation of air-permeable organisms. The ozone layer that works and the planet’s magnetic field together block UV rays, allowing life on the Earth’s surface. Other important functions of the atmosphere include transporting water vapor, providing useful gases, and helping to burn meteors before they collide with the Earth’s surface and adjust the temperature.

The recent phenomenon of these phenomena is known as “the effect of global warming”; the tiny particles in the atmosphere help to block thermal energy emitted from the Earth, leading to higher average temperatures on the Earth’s surface. Carbon dioxide, water vapor, methane, and ozone are considered greenhouse gas emissions. Without global warming, the average temperature on the Earth’s surface will reach -18 ° C, and life may be dead.

Weather and climate on Earth

The earth can be divided into belts with almost homogeneous climatic conditions, according to the latitude. For example, belts located from the equator to the polar regions can be divided into tropical, subtropical, temperate and polar regions. The climate can also be classified according to temperature and rainfall, as well as classification of climatic zones according to regular air masses. The climate classification system for Coben (according to Edmund Coben’s pupil Rudolph Geyer’s modification) consists of five large groups: wet, dry and humid wetlands, located midway, continental regions, and cold polar regions, To more specific areas.

The atmosphere is upper

The atmosphere above the troposphere is usually divided into the stratosphere (the upper part of the atmosphere, the mesosphere and the thermosphere). This layer is the point at which the magnetic field interacts with the solar wind, and the ozone layer is an important part of the atmosphere for the continuation of life on the surface of the planet. This layer is one of the components of the stratosphere that partially protects the Earth’s surface from ultraviolet radiation. This is called the “Carman Line” on the surface of the Earth about 100 kilometers, which separates the atmosphere from space.

Because of the thermal power of the planet, some of the molecules on the outer edge of the Earth’s atmosphere are so fast that they escape the planet’s gravity. This leads to leakage or escapes from the atmosphere into space slowly, though always. Because hydrogen gas is light and has low molecular weight, its escape velocity is greater, and its escape rate is greater than that of other gases. The leakage of hydrogen gas into outer space is a contributing factor in changing the state of the earth from the initial reduction to the current state of oxidation. It is worth mentioning that photosynthesis is a source of free oxygen, but some believe that the loss of reduction factors such as hydrogen gas is a necessary prerequisite for the accumulation of oxygen gas in the atmosphere on a large scale. Thus, the ability of hydrogen gas to escape the atmosphere of the planet may be Has affected the nature of life on the planet. At present, with the atmosphere rich in oxygen gas, most hydrogen gas turns into the water before it has the chance to escape from the atmosphere into outer space. But the loss of most hydrogen gas is due to the destruction of methane in the upper atmosphere.

the magnetic field

The Earth’s magnetic field is formed in the form of a near dipole magnetic field, with the magnetic field poles currently converging from the planet’s two geographic poles. According to the dynamo theory, the planet’s magnetic field is generated inside the molten outer pulp layer. The heat at this place leads to thermal convection movements of the heat-conducting material, generating electrical currents. This, in turn, leads to the magnetic field of the planet. It should be noted that the movements of convection at the core of the earth is characterized by random nature and periodic change in the adjacent. This, in turn, leads to reflections in the magnetic field at irregular intervals that occur on average a few times every million years. It is worth mentioning that the last reflection in the magnetic field has occurred about 700,000 years ago.

The magnetic field of the magnetosphere is its magnetic envelope, which helps to deflect the fine particles found in the solar wind from the Earth. The sun’s edge is about 13 times the radius of the Earth. The collision between the Earth’s magnetic field and the solar wind is also caused by the so-called van Alen radiation belts, two concentric zones and round areas with protrusions with precise particles charged with energy. When plasma (high ionizing gases) enters the magnetic poles, the twilight is formed.

Orbit and rotation of the planet Earth


The rotation of the earth around its axis for the sun – the average solar day – is about 86,400 seconds of the average solar time. Each second of these seconds is slightly longer than the second in the international system of units because the solar day is now slightly longer than the solar day of the 19th century due to the acceleration of the tidal movement. The rotation of the earth around its axis according to the stars Which are called the average asteroid name. It is estimated at 86164.098903691 seconds of the average solar time (UT1) or (23 x 56 d 4.09053083288 w). As for the rotation of the earth around itself in accordance with the average and advanced spring equinox, which some call the error of “star day” or “astronomer”, it is estimated at 86164.09053083288 seconds of the average solar time (23 x 56 d 4.09053083288 w). Thus, the astronomical day is shorter than the star day by about 8.4 parts per second. The length of the average solar day can be determined for the periods between 1623-2005 and 1962-2005. Through the use of “references to the body of the measurement of global Earth circulation”.


The Earth revolves around the sun at about 150 million kilometers every 365.2564 average sun or an astronomical year, which makes the sun look like Earth, moving east for stars at 1 ° / day, or the sun or moon every 12 hours. Because of this movement, on average it takes 24 hours – about the equivalent of a solar day – to complete a cycle around its axis until the sun returns to the meridian. The average orbital velocity of the Earth is estimated at about 30 km/sec (108,000 km / h), which is considered fast enough to cover the distance of the Earth’s diameter (about 12,600 km) in seven minutes and the distance to the Moon (384,000 km) in four hours.

The moon orbits the earth around the center of the mass every 27.32 days, depending on the stars in the background. When the above is added to the rotation of the earth and the moon around the sun, the period of the lunar month (that period between two satellites) is about 29.53 days. The earthly observer of the celestial Arctic observes that the movement of Earth and the Moon and their pivotal rotation are all counterclockwise.

The Earth and the solar system are located in the Milky Way galaxy, orbiting 28,000 light-years from the center of the galaxy. The Earth is currently 20 light years above the level of the galaxy on the spiral arm of the mighty.

Seasons and tilt the axis of the earth

Due to the tilt of the Earth’s axis, the amount of sunlight that reaches any point on the Earth’s surface varies over the months of the year. Summer in the northern hemisphere takes place when the North Pole moves to the sun, and the winter is resolved when the pole moves away from the sun. During the summer, the day lasts longer and the sun is higher in the sky. In the winter, the climate becomes generally cooler and the day is shorter. Above the Arctic circle, the situation becomes extreme. The sun does not shine at all, but the polar night falls for six months. In the southern hemisphere, the situation is completely reversed: the south pole is in the opposite direction of the Arctic direction.

According to astronomical rules, the four seasons are determined by coups (points in the orbit of the maximum axial direction toward or away from the sun) as well as the equinoxes when the tilt and direction of the sun are vertical. The winter solstice occurs on December 21 and the summer solstice occurs on June 21. Spring equinox occurs on March 20, while autumnal equinox occurs on September 23. The tilt angle is relatively constant over long periods of time. However, the axis is also subject to reeling (irregular tremors or movements occurring in the Earth’s axis by the sun and the moon) every 18.6 years. Also, the direction of the Earth’s axis (not the angle) also changes over time in a circuit-shaped cycle to a full cycle every 25,800 cycles a year. This phenomenon is called a pivotal initiative, and this circular progression is the cause of the difference between the astronomical year and the orbital year. These two movements occur because of the different polarization of the sun and moon at the crest of the Earth’s equator.

If one looks at the poles of the Earth, it is noticed that the poles are also fluttering a few meters on the earth’s surface. This polar movement consists of several periodic components, all referred to as the pseudo-cyclical movement. In addition to the annual component of the movement, there is a 14-month cycle known as Chandler’s Tenderer, a movement that takes about 14 months to orbit the Earth’s axis. The rotation speed of the earth varies, resulting in a phenomenon known as the length of the day. In addition to the annual component of the movement, there is a 14-month cycle known as Chandler’s Tenderer, a movement that takes about 14 months to orbit the Earth’s axis. The rotation speed of the earth varies, resulting in a phenomenon known as the length of the day. In addition to the annual component of the movement, there is a 14-month cycle known as Chandler’s Tenderer, a movement that takes about 14 months to orbit the Earth’s axis. The rotation speed of the earth varies, resulting in a phenomenon known as the length of the day.

The moon… The moon of the earth

Diameter3,474.8 km
2,159.2 miles
Bloc7.349 × 10 22 km
8.1 x 10 19 tons (short)
Semi-main axis384,400 miles
238,700 miles
Tropical period27 days, 7 hours and 34.7 minutes

The moon is a large Earth-like appellation and is about a quarter of the Earth’s diameter. The moon is the largest follower of the solar system, for the size of its planet. The satellites orbiting other planets are called satellites.

Gravity between the Earth and the Moon results in the phenomenon of tides on the Earth’s surface. This same effect on the Moon has led to the long-term limitation: that is, the rotation period is the same as the time it takes to rotate around Earth. As a result, he always faces the planet with only one face. As the moon turns around the Earth, the sun illuminates different parts of its face, leading to the appearance of different lunar phases. The bright part of the moon is separated from the dark part by the solar line separating the illuminating part and the dark part. Due to the Earth’s tidal interactions, the Moon is about 38 millimeters away from the Sun per year. Over the course of millions of years, these simple changes – in addition to increasing Earth’s length by 23 ppm a year – will make tremendous changes. For example, during the Devonian era (about 410 million years ago) there were 400 days a year and each day lasted 21.

The Moon greatly affects the evolution of life on earth, by helping to temper the climate on the planet. Both ancient biology studies and computer simulations show that the stability and stability of the Earth’s axis is caused by the tidal interactions with the Moon. Some theorists believe that without this constancy in the Earth’s axis versus the torque caused by the sun and other planets on the spike at the equator, the rotation of the axis may be unstable at random, leading to massive changes to the planet over millions of years Such as those that happened with Mars. If the axis of the earth’s rotation approached the surface of the virtual circle of the path of the sun, it may cause a very harsh weather due to the very large seasonal differences that will occur; as one of the poles will head towards the sun directly during the summer and will go away During the winter. Scientists studying planets and celestial bodies who have studied the effect of this on the planet have predicted that this could lead to the death of all large-scale animals and the elimination of plant life. But the subject is still controversial and may be determined by the future studies of Mars – a planet that is rotating and tilted to its axis like the Earth but not followed by a large moon, and his heart is not liquid.

The observer observes the moon from the Earth, that it is far enough to appear in the shape of a disk with a clear shape like the sun. The angular size (or angular angle) of these two bodies is similar; for although the sun’s diameter is about 400 times greater than that of the moon, it is also about 400 times farther from the earth than the distance from the moon. Total eclipses and annular eclipse on the Earth’s surface.

The impact theory of the giant body is one of the most widely accepted theories that explain the origin of the moon. The theory is that the moon may be the result of the collision of a primitive Earth-sized planet called them in the early stages of the Earth. This assumption (among other assumptions) explains the relative lack of iron and fly elements on the moon, as well as the fact that the moon’s composition is almost identical to that of the Earth’s crust.
The planet’s validity to life

A planet that is fit for a life is called a settlement, even if it has not actually lived. Earth provides the essential conditions for the presence of water and the appropriate environment in which complex organic molecules and energy can be gathered to support and promote food metabolism. Several factors contribute to the creation of conditions necessary for life on the planet. These factors are the planet’s distance from the sun and its movement in Its orbit, instability, and rotation rate around its axis, deviation from it, its geological history, its permanent atmosphere, and its protective magnetic field.


It is sometimes said that the forms of life on earth represent the biosphere. It is generally thought that the biosphere has been in existence for about 3.5 billion years. The planet is the only place in the universe where life exists. Even more, some scientists believe that suitable places for life like Earth are rare in the universe. The biosphere is divided into a number of biotic environments in which a large number of similar plants and animals live. One of the factors that separate biotic environments is the latitude and land level from sea level. The terrestrial biosphere environments of the Arctic Circle, the Antarctic Circle or the high elevations are free of any form of animal or plant life while the largest variety of life forms at the equator.

Exploitation of land and natural resources

The Earth provides the resources necessary for man to exploit them in achieving useful goals. Some of these resources are not renewable, such as mineral fuels, and these resources cannot be recovered in a short period of time. Large quantities of fossil fuel deposits have been obtained from the earth’s crust, which consists of coal, oil, natural gas, and methane compounds. These deposits were used by humans to produce energy and as raw material for chemical reactions. Mineral raw materials are also formed in the Earth’s crust through the process of ore or earth metals from the erosion of their layers and the movements of geological technologic plates. These materials are rich sources of many minerals and other beneficial elements.

The Earth’s biosphere provides many vital products for humans, including but not limited to food, wood, drugs, medicines, oxygen, and the reuse of many organic waste and residues. The land-based ecosystem depends on the surface of the soil and cleans water. The ecosystem of the oceans depends on the dissolved nutrients washed away from the land. Human lives on land through the use of primary building materials in the construction of residential shelters. In 1993, human land use ratios were as follows:

Pasture pasture

Uses of landpercentage
Agricultural lands13.13%
Permanent crops4.71%
Urban areas1.5%
Other uses30%

In 1993, the area of irrigated land was estimated at 2,481,250 km².

Natural and environmental risks

Large areas of the Earth are exposed to harsh climatic conditions such as cyclones, tropical storms and tropical isles. Many places are also subject to earthquakes, landslides, tsunamis, volcanic eruptions, typhoons, landslides, snowstorms, floods, drought and other natural disasters.

In addition, many human-populated areas are exposed to many types of human-induced pollution such as air, water, acid rain, toxic substances and plant disappearance (due to, inter alia, overgrazing, deforestation and desertification), disappearance of wildlife and extinction Some types of animals and soil erosion and the lack of some useful elements and the depletion of soil and the emergence of exotic organisms.

Scientists agree that there is a close link between human activities and global warming due to the increased carbon dioxide emissions from factories and from the growing waste of transportation on fuel. The earth’s population of about 6 billion now has about 500 million cars and buses, all of which export carbon dioxide and other harmful gases, all of which are increasing and accumulating these gases in the atmosphere. This is expected to lead to major changes on the ground such as warming, melting glaciers and Antarctic ice melting, which will lead to increased water levels in the oceans and seas, which means that countless islands and all lowlands such as the Netherlands will be doomed Drowning. High temperature changes also increase the severity of hurricanes and storms, and increase the resulting destruction.

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