Who has information about the earth's surface? Just wait five minutes.

Like other terrestrial planets, the earth's interior consists of a silicon crust, a highly viscous mantle and an inner core, and the inner core consists of a non-viscous liquid outer layer and a solid inner layer. The convection of conductive substances in the liquid part of the core makes the earth produce a weak geomagnetic field.

Metals in the earth's interior are constantly pouring out of the surface through volcanoes and ocean cracks (see submarine expansion). Most of the rocks that make up the crust are less than 1 100 million (1× 108) years old. The oldest known crust is about 4.4 billion (4.4× 109) years [2].

Generally speaking, most of the mass of the earth consists of the following elements:

Iron: 34 .6%

Oxygen: 29 .5%

Silicon: 15 .2%

Magnesium: 12 .7%

Nickel: 2 .4%

Sulfur: 1 .9%

Titanium: 0 .05%

Other elements: 3 .65%

Look at the gravity distribution inside the earth.

[edit] internal

The temperature inside the earth is as high as 5270K K, and the heat inside the planet comes from the "accretion" at the beginning of its formation (see gravitational binding energy). The subsequent heat comes from the decay of radioactive elements such as uranium, thorium and potassium. The heat reaching the surface from the interior of the earth is only 1/20000 of the solar energy received by the surface.

The interior of the earth is divided into:

0-60 km-lithosphere

0-30/35km-Shell

30/35-2900 km-mantle

100-700km-asthenosphere

2900-5 100 km-outer core of the earth's core

5 100-~6375 km-core

[Editor] Earth core

The average density of the earth is 55 15kg/m3, which is the denser planet in the solar system. However, the density of materials on the earth's surface is only about 3000kg/m3, so it is generally believed that there are high-density materials in the core-in the early days of the formation of the earth, about 4.5 billion years ago (4.5× 109), the earth was almost composed of molten metal, which led to the process of high-density materials gathering to the center of the earth and low-density materials moving to the surface (see planetary differentiation). The core is mostly composed of iron (80%), and the rest is basically nickel and silicon. High-density elements such as uranium are either rare elements on the earth or exist in the crust in the form of light elements (see the entry of felsic minerals).

The core is located in the Gutenberg interface, and the core is divided into two parts by Riemann interface: the core with a radius of about 1250km, that is, the G layer, and the liquid outer core with a distance of about 3500km from the center of the earth, that is, the E layer and the F layer. F layer is the transition layer between the core and the mantle.

Generally speaking, people think that the earth's core is a solid core mainly composed of iron and a part of nickel. A different view is that the inner core may be composed of a single iron crystal. The outer core wrapped in the outer layer of the inner core is generally considered to be composed of liquid iron mixed with liquid nickel and other light elements. It is generally believed that the convection of the outer core and the rapid rotation of the earth-through the generator theory (see Coriolis force)-are the reasons for the geomagnetic field. The solid core is too hot to produce a permanent magnetic field (see Curie point). But the inner core can still maintain the magnetic field generated by the liquid outer core.

Recent observational evidence shows that the rotation speed of the inner core may be slightly faster than that of other parts of the earth: the difference is about 2 degrees per year (Cominsdeu-P82).

[edit] mantle

The area extending from the Gutenberg surface with a depth of about 2900 kilometers to the Moho surface with a depth of about 33 kilometers around the core is called the mantle. The pressure at the bottom of the mantle is about 1.40 ATM( 140 GPA). Most of them are composed of substances rich in iron and magnesium. The melting point of a substance depends on the force at its position. With the deepening of entering the mantle, the pressure gradually increases. The lower part of the mantle is generally considered as a solid, while the upper mantle is generally considered as a plastic material. The viscosity range of materials in the upper mantle region is1021~1024 pa? S, the specific data changes with depth [3], so the upper mantle may flow slowly.

The inner core of the earth is solid and the outer core is liquid, but the mantle is solid or plastic. The reason is that the melting point, temperature and pressure of different formation materials increase with depth. When the surface temperature is low enough, the main components of ferronickel and siliceous rocks are solids. The siliceous rocks in the upper mantle are solid and partially melted, but generally speaking, due to high temperature and low pressure, the viscosity is relatively low. Due to the great pressure, the viscosity of the lower mantle is much higher than that of the upper mantle. Because of the low melting point of the alloy, the outer core of nickel-iron metal is still in liquid state despite great pressure. Finally, extreme pressure makes the core strong.

[Editor] Bread crust

The crust refers to the underground area with an average depth of about 33km from the ground to Moho. The thin ocean bottom shell is composed of high-density mafic silicate (mafic rock). Magnesite is the basic raw material of ocean basin. The thick continental crust is composed of low density potassium sodium aluminosilicate (felsic mineral). The boundary between the crust and the mantle presents different physical characteristics: First, there is a physical boundary called Mohorovicic interface, which changes the propagation rate of seismic waves. It is generally believed that the reason for the boundary surface is that the upper rock contains plagioclase and the lower rock contains no feldspar. The second difference is that there are chemical changes between the crust and the mantle-the difference between ultraalkaline deposits without magnetic field in the deep ocean crust and plagioclase, and the difference between ophiolite produced by the extrusion of the ocean crust to the continental crust.

[Edit] Biosphere

See the main item: life.

The earth is the only known place where life still exists. The life form of the whole planet is sometimes called a part of the biosphere. The biosphere includes the lower atmosphere, all hydrosphere and upper lithosphere. It is generally believed that the biosphere evolved from 3.5 billion years ago (3.5× 109). The biosphere is divided into many different biota. According to the similar living range, it can be divided into flora and fauna. On the ground, the biological community is mainly divided by latitude, and the terrestrial biological community lacks the related animals and plants in the South Arctic Circle, and the active biological community is mostly near the equator.

[editor] atmosphere

The cross section of the earth from the core to the atmosphere. This part is commensurate.

See main entry: Earth's atmosphere.

The earth has a dense atmosphere, which consists of 78% nitrogen, 2 1% oxygen and 1% argon mixed with a small amount of other gases, including carbon dioxide and water vapor. The atmosphere is a buffer layer between the earth's surface and the sun. The composition of the earth's atmosphere is unstable, and its composition is also affected by the biosphere. For example, a large amount of free divalent oxygen in the atmosphere is produced by plants on the earth through solar energy. Without these plants, oxygen would quickly recombine with matter by burning. Free (uncombined) oxygen is of great significance to life on earth.

The earth's atmosphere is layered. It mainly includes troposphere, stratosphere, mesosphere, thermosphere and escape layer. The layers around the world are not completely consistent, and they change with the seasons.

The total mass of the earth's atmosphere is about 5.1×10/8kg, but the total mass of the earth is 0.9ppm.

[edit] hydrosphere

See main item: ocean.

The earth is the only planet in the solar system with liquid water on its surface. Water covers 71%of the earth's surface (97% is seawater and 3% is fresh water [4]). Water exists in five oceans and seven continents. Solar orbit, volcanic activity, gravity, greenhouse effect, geomagnetic field and oxygen-enriched atmosphere make the earth a water planet.

The earth is on the edge of the orbit, and the temperature is enough for liquid water to exist. Without proper greenhouse effect, all the water on the earth will freeze into ice. Paleontological evidence shows that if blue-green algae (cyanobacteria) appear in the ocean later, the greenhouse effect will not be enough to maintain the existence of liquid water on the earth's surface, and the ocean may freeze between 65.438+million and 65.438+0 billion years, resulting in ice age events.

At that time, on a planet like Venus, gaseous water blocked the ultraviolet radiation of the sun. Hydrogen in the atmosphere is ionized by the blowing solar wind, the effect is slow but the result cannot be changed. This is also a hypothesis why there is no water on Venus: without hydrogen atoms, oxygen will materialize with the surface and remain in soil minerals.

There is a thin ozone layer in the earth's atmosphere. Ozone absorbs most of the excess high-energy ultraviolet radiation in the atmosphere in the stratosphere, which reduces the cracking. Ozone can only be produced by a large number of free divalent oxygen atoms in the atmosphere, so the production of ozone also depends on the biosphere (plants). The ionosphere generated by the geomagnetic field also protects the earth from the direct attack of the solar wind.

Finally, volcanic activity also constantly releases water vapor from the interior of the earth. The earth digests limestone in the mantle and volcanoes with water and carbon, producing carbon dioxide and water vapor (see planetary framework). It is estimated that the total amount of water still left in the mantle is 10 times of all the water in the ocean now, although most of the water in the mantle may never be released to the surface.

The total mass of the earth's hydrosphere is about

physical geography

[Editor] Climate

See main project climate.

Because the earth's climate has changed greatly since ancient times, and this change will continue to evolve, it is difficult to summarize the earth's climate. Natural disasters related to weather and climate on earth include tornadoes, typhoons, floods and droughts.

These two polar climates are separated by two regions with little temperature difference: the vast tropical climate near the equator and the subtropical climate with slightly higher latitude. The precipitation patterns in different regions are also very different, ranging from a few meters per year to less than one millimeter per year.

[Edit] Terrain

A topographic map of the earth's surface (please click to enlarge) formed by satellite photos combined with flat Carrée projection method, with a total land area of about 5 10072 million km2, of which land accounts for about 29.2% (148.94 million km2) and the remaining 70.8% (361130). The land is mainly in the northern hemisphere, with four continents: Europe, Asia, Africa, America, Australia and Antarctica, as well as many islands. The oceans include the Pacific Ocean, the Atlantic Ocean, the Indian Ocean and the Arctic Ocean and their affiliated waters. The coastline is * * * 356,000 kilometers.

Extreme altitude:

Lowest point on land: Dead Sea? 4 18m

The lowest point in the world: Mariana Trench in the Pacific Ocean? 11.034m.

The highest point in the world: Mount Everest is 8844.43 meters.

[Editor] Natural disasters

Main projects: Natural disasters Most areas and their living things have suffered from extreme weather, such as tropical cyclones, hurricanes or typhoons. Earthquakes, landslides, tsunamis, volcanic eruptions, tornadoes, limestone pits (land subsidence), floods, droughts and other climatic anomalies and disasters have also occurred in many areas.

[Editor] Human Geography

[edit] natural resources

See natural resources entry.

The crust contains a large number of fossil fuel deposits: coal, oil, natural gas and methane inclusions. These sediments are used by humans to make energy and as feed for other chemicals.

Under the action of corrosion and planetary tectonics, iron-bearing minerals constitute the crust. These metal ores contain various metals and useful chemical elements.

The earth's biosphere can produce a large number of useful biological outputs, including (but not limited to) food, wood, medicine and oxygen. The biosphere can also recycle a lot of organic waste. Ground ecosystem depends on topsoil and fresh water, while marine ecosystem depends on nutrients dissolved after scouring on land.

It is common for human beings to exploit the natural resources of the earth.

Some of these resources, such as fossil fuels, are difficult to regenerate in a short time. This is the so-called non-renewable resources. The plundering of non-renewable resources by human civilization has become one of the important debates in the modern environmental protection movement.

[edit] political map

Land boundary:

The total land boundary of the world is * * * 250,472 kilometers (the * * * boundary is only calculated once). Two of them, People's Republic of China (PRC) and Russia, have the most borders, with 65,438+04 countries respectively. 43 countries and regions are landlocked: Afghanistan, Andorra, Armenia, Austria, Azerbaijan, Belarus, Bhutan, Bolivia, Botswana, Burkina Faso, Burundi, Central African Republic, Chad, Czech Republic, Ethiopia, Vatican City, Hungary, Kazakhstan, Kyrgyzstan, Laos, Lesotho, Liechtenstein, Luxembourg and Malawi. Niger, Paraguay, Rwanda, San Marino, Slovakia, Swaziland, Switzerland, Tajikistan, The former Yugoslav Republic of Macedonia, Turkmenistan, Uganda, Uzbekistan, West Bank, Zambia and Zimbabwe; The other two countries are dual landlocked countries, Liechtenstein and Uzbekistan.

97 countries and other entities are island countries with no borders with other countries. They include: American Samoa, Angola, Antigua and Barbuda, Aruba, ashmore and Cartier, Bahamas, Bahrain, Baker Island, Barbados, Key India, Bermuda, Bouvet Island, british indian ocean territory, British Virgin Islands, Cape Verde, Cayman Islands, Christmas Island, Krypton Island, Corcos Islands, Comoros, Cork Islands and Coral Island. Falkland Islands, Faroe Islands, Fiji, French Polynesia, French Southern Hemisphere and Antarctic Dependencies, Glorieuses, Greenland, grenada island, Guam, Guernsey, Hede Island and MacDonald Island, Howland Island, Iceland, Jamaica, Cayman Islands, Japan, Jarvis Island, Jersey Island, Johnston Atoll, Vanova Island, Kingman Reef, Gilbass, Madagascar, etc. Mauritius, Micronesia (Federated States of), Midway, Montana, Nauru, Nafusai, New Caledonia, New Zealand, Niue, Puerto Rico, norfolk island, French Reunion, Saint Helena, Saint Kitts and Nevis, Saint Lucia, Saint Pierre and Michelo, Saint Vincent and the Grenadines, American Samoa, Sao Tome and Principe, Seychelles, Singapore, Solomon Islands, South Georgia and South Sandwich Islands.

Maritime statement:

There are various situations. On the whole, however, most countries abide by the proposition put forward in 1982 United Nations Convention on the Law of the Sea.

Adjacent area: mostly 24 nautical miles (NM), but it can be changed.

Continental shelf: most of them are 200 meters or exploration depth, and some are called 200 nanometers or to the continental margin.

Special fishing area: most of them are called 200NM, but they can be changed.

Special economic zones: most of them are 200NM, but they can be changed.

Territorial sea: most of it is 12NM, but it can be changed.

Note: Border conditions with neighboring countries in some cases prevent many countries from expanding their fishing areas and economic zones to 200 nautical miles.

43 countries and regions are completely landlocked (see landlocked countries)

[Edit] Land use

Cultivated land: 10.73%

Permanent cultivated land: 1%

Others: 88.27% (200 1)

Irrigate land:

27 14320 km2 (1998)

[Editor] Human beings

Astronaut Bruce McCandless II is taking a spacewalk. Population: 6525170264 (July 2006, [5], Central Intelligence Agency)

At present, there are two people living in the orbit of the International Space Station around the earth. The members of the International Space Station rotate every six months, so during the rotation, more people will be on the space station, and sometimes others will "travel" briefly outside the atmosphere.

Generally speaking, by 2004, about 400 people had gone out of the earth (into space). Most of them say that they have regained their understanding of the earth and realized its importance in maintaining human life. At the same time, they are all amazed at the beauty of the earth in space. These are things that they (humans) can't feel when they live on the surface.

See Space Colonization Entrance.

The northernmost human settlement on earth is on guard at Esme Island. The southernmost human settlement is Amundsen-Scott Antarctic Station in Antarctica. This American Antarctic station is almost at the South Pole.

Age structure:

0- 14 years old: 27.8% (male 919726623; Female 870,468, 158)

15-64 years old: 64.9% (male 2117230183; 2066864970 females)

Over 65 years old: 7.3% (male 207903775; Female 263, 627, 270)

Because some countries do not keep the information of age structure, there is a slight error between the total world population and the global age structure (2005).

Median age:

Total: 27.6 years old

Male: 27 years old.

Female: 28.2 years old (2005)

Population growth rate:

1. 14%(2005); 73 million people/year; 200 thousand a day

Birth rate:

20. 15 new population/1000 (2005); 1.400 million/year; 383,600 pounds a day

Mortality rate:

8.78 Death population/1000 (2004); 60 million/year; Every day 164400

Sex ratio:

Birth: 1.06 boy/girl.

/kloc-under 0/5 years old: 1.06 boy/girl

15-64 years old: 1.03 male/female

Over 65 years old: 0.79 male/female

Total number: 1.0 1 male/female (estimated in 2005)

Infant mortality rate at birth | Infant mortality rate: (estimated in 2005)

Total: 50. 1 1 dead population/1000 newborn babies.

Male: 52. 1 dead population/1000 newborn babies.

Female: 48.0 1 dead population/1000 newborn babies.

Average life expectancy:

Total population: 64.33 years old

Male: 62.73 years old

Female: 66.04 years old (estimated in 2005)

Total birth rate:

2.6 Birth of babies/women (estimated in 2005)

Literacy ability

15 years old and above can read and write.

Total population: 77%

Male: 83%

Female: 7 1% (1995)

[Editor] Government

So far, the earth has not formed a government agency that rules the whole planet. At present, all areas of the earth's land surface are ruled by a certain country, except Antarctica. There is a global international organization, the United Nations. However, the United Nations is mainly an international exchange forum, and its ability and power to realize the law are limited.

Administrative regions (see administrative regions of the world)

At present, there are 27 1 countries, territories and other governance methods on the earth.