Earth introduction

The earth is the third planet in the solar system from the inside out, and the earth-like planet with the largest diameter, mass and density in the solar system. It is also often called the world. The word Earth in English comes from Old English and Germanic. The age of the earth is 4.4-4.6 billion years old. There is a natural satellite-the moon, which revolves around the earth in a period of 30 days, while the earth revolves around the sun in a period of nearly 24 hours and one year. Disney has a documentary with the same name.

The name "earth" comes from the word "earth" in old English. When people don't know that the earth is a planet, the word "earth" only refers to the land where people walk. Later, the word not only refers to the earth under our feet, but also gradually refers to the whole world itself. As for when the word appeared, there is no way to verify it. The earth is one of the eight planets in the solar system, with the international name "Gaia", ranking third in the order from near to far from the sun. It has a natural satellite-the moon, forming a celestial system-the earth-moon system. ? Earth position map

1. This planet inhabited by human beings is one of the eight planets in the solar system. Its average distance from the sun is 1 49.6 million kilometers (1astronomical unit), ranking third among the planets, and its equatorial radius is 6378.2 kilometers, ranking fifth among the planets. 2. It refers to the whole world: if teenagers are better than the earth, then the country is better than the earth. ? -Green? Liang Qichao's young chinese Theory? The earth is an irregular ellipsoid with slightly flat poles. The earth rotates from west to east and revolves around the sun at the same time. The combination of the earth's rotation and revolution has produced the alternation of day and night and seasonal changes on the earth (the speed of the earth's rotation and revolution is uneven). At the same time, due to the gravity of the sun, the moon and nearby planets, as well as the influence of many factors such as the earth's atmosphere, ocean and materials inside the earth, the direction of the earth's rotation axis will change in space and the earth itself. The inertial centrifugal force produced by the earth's rotation makes the spherical earth gradually expand from the poles to the equator, becoming a slightly flat ellipsoid of revolution at present, and the polar radius is about 2 1 km shorter than the equatorial radius. ? The earth has accumulated from the primitive solar nebula to the present. At present, the best estimate of the age of the earth is 4.55 billion years. Generally speaking, the age of the earth refers to its astronomical age. The astronomical age of the earth refers to the time from the beginning of the earth to the present, which is closely related to the hypothesis of the origin of the earth.

Orbit data

How far is it from apohelion? 152,097,70 1? km( 1.0 16？ 7 10? 333? 5? AU)？

Perihelion distance? 147,098,074? km(0.983？ 289? 89 1? 2? AU)？

Semi-major axis of orbit? 149,597,887.5? km( 1.000？ 000? 1 12? 4? AU)？

Semi-minor axis of orbit? 149,576,999.826? km(0.999？ 860? 486? 9? AU)？

Orbit circumference? 924,375,700? km(6. 179？ 069? 900? 7? AU)？

Track eccentricity is 0.0 16? 7 10? 2 19?

Average speed? 29.783? Km/s (107,218? Kilometers/hour)?

Maximum speed? 30.287? Km/s (109033? Kilometers/hour)?

Minimum speed? 29.29 1? Km/s (105,448? Kilometers/hour)?

Orbit inclination? 0 (7.25 to the sun equator)?

Ascending the Right ascension? 348.739? 36 ?

Perihelion angle? 1 14.207? 83 ?

Satellite? 1 (Moon)?

physical features

Ellipticity? 0.003? 352? 9?

Average radius? 6,372.797? km？

Equatorial radius? 6,378. 137? km？

Pole radius? 6,356.752? km？

Aspect ratio? 0.996? 647? 1?

What is the circumference of the equatorial circle? 40,075.02? km？

Meridian circle circumference? 40,007.86? km？

Average circumference? 40,04 1.47? km？

Surface area? 5 10,065,600? km^2？

Land area? 148,939, 100? km^2(29.2？ %)?

Waters? 36 1, 126,400? km^2(70.8？ %)?

Volume? 1.083? 207? 3× 10^ 12? km^3？

Quality? 5.9742× 10^24? kg？

Average density? 5,5 15.3? kg/m^3？

Equatorial surface gravity acceleration? 9.780? 1? m/s^2(0.997？ 32? g)？

The speed of the universe? 1 1. 186? Km/s (39,600? Kilometers/hour)?

Sidereal day? 0.997? 258? d(23.934？ h)？

Equatorial rotation rate? 465. 1 1? m/s？

Axis tilt? 23.439? 28 1 ?

Arctic Right ascension? Undefined?

Declination? +90 ?

Albedo? 0.367?

Average surface temperature? 287? K( 14？ ℃)?

Maximum surface temperature? 33 1? K(57.7？ ℃)?

Minimum surface temperature? 184? K(-89.2？ ℃)?

atmosphere

Surface pressure? 10 1.3? KPa (sea level)?

Nitrogen? 78.084%?

Oxygen? 20.946%?

Argon? 0.934%?

Carbon dioxide? 0.038 1%?

quality

Cavendish thinks that the mass of the earth is about 5.96×10.24kg? Equatorial radius ra = 6378137m ≈ 6.378×106m, polar radius Rb = 6356752m ≈ 6.357× 10 6m, oblateness e= 1/298.257, ignoring the aspheric surface of the earth. The gravitational acceleration value of a sea level at the equator is GA = 9.780m/s 2, that of a sea level at the North Pole is GB = 9.832m/s 2, the global standard value of gravitational acceleration is G = 9.807m/s 2, and the earth's rotation period is 23 hours, 56 minutes and 4 seconds (sidereal day), that is, T = 8.665438+. ? If we regard the earth as homogeneous and ignore the influence of other celestial bodies, the mass of the earth can be calculated in the following way. ? Method one. On the equator, the gravity of the earth to an object with mass m is equal to the sum of the gravity of the object and the centripetal force accompanying the rotation of the earth, that is, 5.984 * 10 24? kg？ Method 2: In the Arctic, regardless of the earth's rotation, it is calculated as 5.954 * 10 24kg? Method 3: regard the earth as a sphere with uniform mass, ignore the influence of rotation, take the average radius and take the standard value of gravity acceleration. It was 1959, the first photo of the earth taken by astronauts in space.

5.965* 10^24kg？ The distance r between the moon and the earth is = 3.884×10.8m, and the period of revolution of the moon is 27 days, 7 hours and 43 minutes 1 1 sec (sidereal day), that is, T-month ≈ 2.36/kloc-0 /×10.6s, both the moon and the earth. The fourth method is 6.220 * 10 24kg.

temperature

The core temperature is about 6880℃, which is higher than the surface temperature of the solar photosphere (6000℃). The highest temperature on earth occurs when a hydrogen bomb explodes. An explosion can reach 10000000℃, which is 16667 times of the surface temperature of the sun and much higher than the temperature of the core of the sun (14 million degrees Celsius). ? Where is the coldest place on earth? The "cold pole" in the northern hemisphere is located in Oymyakon in eastern Siberia. 196 1 year minimum temperature is–71℃. The "cold pole" in the southern hemisphere is on the Antarctic continent, and the temperature on August 24th, 1960 is–88.3℃.

behaviour of electricity

Negative charge? Reason: The earth rotates from west to east, and the outer side of the geomagnetic field points from the magnetic south pole to the magnetic north pole (that is, the north pole points to the south pole), and the annular current formed is opposite to the rotation direction of the earth, so it is negatively charged.

shape

After long-term accurate measurement, scientists found that the earth is not a regular sphere, but an irregular sphere with slightly flat poles and slightly bulging equator. The equatorial radius of the earth is about 6378. 137Km? Compared with the average radius of the earth, this difference is very small. From the perspective of space, the earth can still be regarded as a regular sphere. If you make a globe with a radius of 1 m according to this ratio, the equatorial radius is only about 3 mm longer than the polar radius, which is difficult for human eyes to detect, so when making a globe, it is always made into a regular sphere.

natural disaster

Earthquake? Landslide? Typhoon? Tsunami hail? Drought? Hurricane? Flood? Cold wave? Blizzard? Acid rain? Natural disasters (20 photos) sandstorms? Desertification? Storm surge? Tornado? Debris flow? Soil erosion? Volcanic eruption? Biological disaster? Avalanche storm Lack of biological chain and so on

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It was not until the Copernican era of17th century that people realized that the earth was just a planet. ? Earth structure map

Of course, the earth can be observed without flying machines, but we didn't have a map of the whole earth until the twentieth century. Photos taken from space should be of certain importance; For example, they are very helpful to weather forecast and storm tracking forecast. How beautiful they are! ? Due to different chemical composition and seismic properties, the earth is divided into different rock formations (depth: kilometers). 0~40? That? Shell? Shell? 40~? 400? Upper position? Manto? Upper mantle? 400~? 650? Transition? Region? Transition zone? 650~2700? Lower? Manto? Lower mantle? 2700~2890? d ' '？ Layer? D "floor? 2890~5 150? Outside? Core? External nucleus? 5 150~6378? Inside? Core? Kernel? The thickness of the earth's crust is different, the ocean is thin and the mainland is thick. The core and crust are entities; The outer core and mantle are fluids. Different layers are separated by discontinuous sections which are obtained from seismic data. One of the most famous is the Moho surface between the crust and the upper mantle. ? Most of the mass of the earth is concentrated in the mantle, and most of the rest is in the core; We live only a small part of the whole (the following value × 10E24kg):? Atmosphere? =? 0.000005 1? Earth (19) and ocean? =? 0.00 14? Shell? =? 0.026? Manto? =? 4.043? Foreign nuclear? =? 1.835? Continental nuclear? =? 0.09675? The core may be mostly composed of iron (or nickel/iron), although it may also be some lighter substances. The temperature in the center of the earth's core may be as high as 7500K, which is hotter than the surface of the sun. The lower mantle may be composed of silicon, magnesium, oxygen and some iron, calcium and aluminum. The upper mantle is mainly composed of olivine, pyroxene (iron/magnesium silicate), calcium and aluminum. We know that these metals come from earthquakes; Samples of the upper mantle reach the surface, just like volcanoes spewing magma, but most of the earth is still inaccessible. The crust is mainly composed of quartz (silica) and other feldspar-like silicates. Generally speaking, the chemical elements of the earth are:? 37.6%? Iron? 29.5%? Oxygen? 15.2%? Silicon? 12.7%? Magnesium? 2.4%? Nickel? 1.9%? Sulfur? 0.05%? Titanium? The earth is the densest star in the solar system. ? Other terrestrial planets may have similar structures and material compositions, but there are also some differences: the moon has at least one small core; Mercury has an oversized core (equivalent to its diameter); The mantle of Mars and the moon is much thicker; The moon and mercury may not have a crust composed of different chemical elements; The earth may be the only earth-like planet with an inner core and an outer core. It is worth noting that our theory about the internal structure of planets only applies to the earth. ? Unlike other terrestrial planets, the earth's crust consists of several solid plates, each of which floats on the hot mantle. It is called plate theory in theory. It is described as having two processes: expansion and contraction. When the two plates move away from each other and the magma below forms a new crust, it will expand. Shrinkage occurs when two plates collide with each other, and the edge of one plate extends below the other plate and is destroyed by heat in the hot mantle. There are many faults at the plate boundary (such as San in California? Andreas fault), and the collision between continental plates (such as the Indian Ocean plate and the Eurasian plate). At present, there are eight major plates:? North American plate? -? North America, the Northwest Atlantic and Greenland? South American plate? -? South America and the southwest Atlantic? Antarctica plate? -? Antarctica and the coast? Eurasian plate? -? Northeast Atlantic, Europe and Asia except India? African plate? -? Africa, the southeast Atlantic and the western Indian Ocean? India and Australia plate? -? India, Australia, New Zealand and most parts of the Indian Ocean? Nazca plate? -? Adjacent areas of the East Pacific and South America? Pacific plate? -? Most of the Pacific Ocean (and Southern California)? There are more than twenty kinds of small plates, such as Arabic and Filipino plates. Earthquakes often occur at the junction of these plates. Drawing a map can make it easier to see the plate boundaries (above). ? The surface of the earth is very young. In a short period of 5 billion years (astronomical standard), the process of erosion and tectonic movement is repeated, and most of the earth's surface is formed and destroyed again and again. In this way, most of the original geographical traces (such as craters formed by the impact of stars) have been removed. As a result, the early history of the earth was obliterated. The earth has existed for 4.5 to 4.6 billion years, but the oldest known stones are only 4 billion years old, and there are only a handful of stones over 3 billion years old. The earliest biological fossils are less than 3.9 billion years old. There is no exact record of the moment when life really begins. 0% of the earth's surface is covered with water. The earth is the only planet that can have liquid water on its surface (although there are liquid ethane and methane on Titan's surface, and there is also liquid water underground on Europa). We know that liquid water is an important condition for life. The heat capacity of the ocean is also an important condition to keep the earth's temperature relatively stable. Liquid water has also caused surface erosion and continental climate diversification, which is a unique process in the solar system (it may have happened on Mars a long time ago). ? The earth's atmosphere is composed of 77% nitrogen, 2 1% oxygen and trace amounts of argon, carbon dioxide and water. When the earth was first formed, there may be a lot of carbon dioxide in the atmosphere, but almost all of it is combined into carbonate rocks, and only a small part is dissolved in the ocean or consumed by living plants. At present, plate tectonics and biological activities maintain the continuous flow of carbon dioxide in the atmosphere to other places and back. A small amount of stable carbon dioxide in the atmosphere is of great significance to maintain the surface temperature through the greenhouse effect. The greenhouse effect increased the average surface temperature by 35℃ (from -2 1℃ in freezing to1℃ in human). Without it, the ocean will freeze and life will be impossible. ? From a chemical point of view, the existence of a large amount of oxygen is very obvious. Oxygen is a very active gas, which is easy to combine with other substances quickly in general environment. The generation and maintenance of oxygen in the earth's atmosphere is completed by biological activities. Without life, there is not enough oxygen. ? The interaction between the earth and the moon slows down the rotation speed of the earth by 2 milliseconds every century. The current survey shows that about 900 million years ago, there were 48 1 day and 18 hours in a year. ? The earth has a medium magnetic field formed by the core current. Due to the interaction of solar wind, the aurora phenomenon is caused by the earth's magnetic field and the upper atmosphere of the earth (see interplanetary medium). The uncertain period of these factors also leads to the relative movement of magnetic poles on the surface; The North Magnetic Pole is now in northern Canada. The atmosphere is the outermost gas layer in the outer circle of the earth, surrounding the ocean and land. There is no exact upper atmospheric limit, 2000? ~? 16000? There are also thin gases and elementary particles at an altitude of 1000 meters. There is also a small amount of air in the ground, soil and some rocks, which can also be considered as a part of the atmosphere. The main components of the earth's atmosphere are nitrogen, oxygen, argon, carbon dioxide and trace gases less than 0.04%. The total mass of gases in the earth's atmosphere is about 5.136×1021g, which is equivalent to 0.86 millionth of the total mass of the earth. Due to gravity, almost all gases are concentrated in the height range of 100 km above the ground, and 75% of the atmosphere is concentrated in the troposphere range from the ground to 10 km. According to the distribution characteristics of the atmosphere, it can be divided into stratosphere, mesosphere and thermosphere above troposphere. Hydrosphere The hydrosphere, which includes oceans, rivers, lakes, swamps, glaciers and groundwater, is a continuous but irregular circle. Overlooking the earth from a height of tens of thousands of kilometers, we can see the white clouds formed by water vapor in the earth's atmosphere and the blue ocean covering most areas of the earth, making the earth a "blue planet". The total mass of the earth's hydrosphere is1.66×1.024g, which is about 1/3600 of the total mass of the earth, and the mass of marine water is about 35 times that of terrestrial water (including rivers, lakes, surface rock pores and soil). If the whole earth had no ups and downs of solid parts, the whole world would be covered by a water layer as deep as 2600 meters. The atmosphere and hydrosphere combine to form the fluid system on the surface. Due to the existence of minerals in the atmosphere, hydrosphere and surface of the earth, the biosphere has formed a natural environment suitable for biological survival under this suitable temperature condition on the earth. People usually refer to living things, including plants, animals and microorganisms. It is estimated that there are about 400,000 species of plants, about 165438+ 10,000 species of animals and at least 65438+ 10,000 species of microorganisms. According to statistics, there are about 500-10 billion species of living things in geological history. However, during the long evolution of the earth, most of them have become extinct. Existing organisms live in the upper lithosphere, the lower atmosphere and the whole hydrosphere, forming a unique biosphere on earth, called biosphere. The biosphere is the only sphere on the earth among all the planets in the solar system. ? We can know the earth without a space probe, but it was not until the twentieth century that we really outlined the whole picture of the earth. ? Of course, getting its image from space is a very important factor. Does the space image of the earth predict the weather, especially typhoons? It is very helpful for forecasting. The earth seen from space is really beautiful, lovely and spectacular. ? According to the chemical composition and seismic characteristics, the main body of the earth can be divided into several layers, and their names and ranges (in kilometers) are marked as follows: 0 ~ 40 crust 40 ~ 2890 mantle 2890 ~ 5 150 outer core 5 150 ~ 6378 inner core? The thickness of solid crust varies greatly, and the crust in marine areas is thin, with an average thickness of about 7 kilometers; The continental crust is much thicker, with an average thickness of about 40 kilometers; ? The mantle is also solid, but it has a very small partially melted region called asthenosphere? The top of the mantle and the whole crust are called lithosphere? ; As for the outer core is liquid and the inner core is solid. ? These different layers are bounded by discontinuities, the most famous of which is the Mohs discontinuity between the crust and mantle. (Mohorovicic? Discontinuous). The mantle occupies the main part of the earth, while the core occupies the second place. As for our living space, it is only a tiny part of the whole earth? (mass, unit is 10 to the 24th power kilogram:? Atmosphere? =? 0.000005 1, ocean? =? 0.00 14? , the crust? =? 0.026, mantle? =? 4.043, outer core =? 1.835, inland core? =? 0.09675,)? The main component of the core is iron? (or iron and nickel), but there may be some lighter substances. The geocentric temperature is about 7,500K, which is higher than the surface temperature of the sun. The main components of the lower mantle may be silicon, magnesium and oxygen, plus some iron, calcium and aluminum; The main components of the upper mantle are olivine and pyroxene. (iron magnesium silicate rock), as well as calcium and aluminum. ? All the above knowledge comes from seismic data. Although the material in the upper mantle is sometimes brought to the surface by lava from volcanoes, we still can't reach the main part of the solid earth, and the current seabed drilling operation has not even dug through the crust. ? Is the composition of the crust mainly timely? (silica) and silicates such as feldspar. ? Overall, the weight percentage of geochemical components is:? Iron 34.6%? , oxygen 29.5%? , silicon 15.2%? , magnesium 12.7%? , nickel 2.4%? , sulfur 1.9%? ,0.05%? Titanium? . ? The earth is the main star with the highest average density. ? Other Earth-like planets also have structures and compositions similar to those of the Earth, but there are also some differences: the proportion of moon nuclei is the smallest; ? The proportion of mercury nuclei is the largest; The letters of Mars and the moon are thicker; There is no difference in chemical composition between the moon and mercury. The earth may be the only one that can be subdivided into an inner core and an outer core. However, please note that our understanding of the interior of the planet mainly comes from theoretical deduction, even for the earth. ? Different from other terrestrial planets? The outermost layer of the earth? (including the top of the crust and the upper mantle) is divided into several pieces and floats on the hot mantle below it. This is the famous theory of plate tectonic movement? . ? This theory mainly describes two kinds of movements: extension and dive. The former occurred in the place where the two plates were far apart, and the magma below them spewed out to form a new crust; The latter occurs when two plates collide with each other, one of which dives under the other plate and finally disappears into the mantle. ? In addition, there are some plate boundaries that cross each other or two continental plates collide with each other. ? Most of the surface of the earth is young? Only about 500 million years, which is really short from an astronomical point of view. However, there are few places where the basement of the earth's crust is exposed, such as Suizhong County, Huludao City, Liaoning Province, China. Because of the long cooling time when granite is formed, the crystals in granite are very developed, and the side length is 1-2 cm, so it is named Suizhong granite. Because erosion and tectonic geological movement continue to destroy and rebuild most of the surface, it is not easy to find early geological records of the surface, such as impact pits. So most of the history of the early earth has disappeared. ? The earth is about 4.5 to 4.6 billion years old, but the oldest known rocks are only about 4 billion years old (the earth was a fireball formed by molten magma a long time ago), and rocks over 3 billion years old are very rare. ? The oldest biological fossils are not earlier than 3.9 billion years ago, and there is no record of the critical period of the origin of life. ? 7 1% of the earth's surface area is covered by water, and the earth is the only planet in the solar system with liquid water on its surface? There is liquid ethane or methane on Titan's surface, and liquid water may be hidden under Europa's surface, but the existence of liquid water on the earth's surface is still unique. ? Liquid water is an indispensable element in our known life forms; Because of the large specific heat of water, the thermal volume of the ocean has become a great contributor to keeping the earth's temperature constant; Liquid water is also the main force of erosion and weathering on land, the only place in the solar system that has this effect? In the composition of the earth's atmosphere, 78% is nitrogen, 2 1% is oxygen, and then there are trace amounts of argon, carbon dioxide and water vapor.

Historical era? A million years? Major event? Gangdom? The hidden generation? 4570? The earth appeared? Native generation? 4 150? The first living thing on earth-bacteria? Dionysus generation? 3950? Archaea appeared? The early Yuhai generation? 3850? There are oceans and other waters on the earth? Archaean? Archaean? 3800? Archaean? 3600? Blue-green algae appear? Middle Archean? 3200? Neoarchean? 2800? The first ice age? Proterozoic? Cheng Tieji? 2500? Layer invasion? 2300? Yamagata? 2050? Ancient Proterozoic? Consolidation period? 1800? Capping age? 1600? Yan Chu Ji? 1400? Mesoproterozoic? Narrowband discipline? 1200? Stretching period? 1000? The formation of Roddy Niagu? Ice age? 850? Snowball incident? Neoproterozoic? Eddie Karadji? 630? +5/-30? Multicellular organisms appear? Phanerozoic? Paleozoic? Cambrian? 542.0? ? 1.0? Cambrian explosion of life? Ordovician? 488.3? ? 1.7? Fish appear; Is seaweed flourishing? Silurian? 443.7? ? 1.5? Terrestrial gymnosperms appear? Devonian? 4 16.0? ? 2.8? Fish boom? Amphibians appear? Insects appear? Seed plants appear? Lycopodium and Equisetum showed up? Carboniferous? 359.2? ? 2.5? Insects thrive? Reptiles appear? Coal forest? Gymnosperms and reptiles? Mesozoic? Permian? 299.0? ? 0.8? During the Permian mass extinction, 95% of the life on the earth became extinct? Pangea was formed? Triassic? 25 1.0? ? 0.4? Dinosaurs appeared? Egg-laying mammals appear? Jurassic? 199.6? ? 0.6? Do you have marsupials? Birds appear? Gymnosperms flourish? Angiosperms appear? Cretaceous? 99.6? ? 0.9? The rise and extinction of dinosaurs? Cretaceous-Tertiary extinction event, 45% of the life on the earth became extinct? Mammals with placenta appear? A new generation? 65.5? ? 0.3? Up to now? It is a common natural phenomenon that the sun and the moon rise and set every day. Whether the earth is in motion or at rest has been debated for centuries. ? The earth revolves around the sun. What method can be used to prove that the earth is spinning? ? It is said that Galileo did an experiment: many lenses with different diameters were piled on the balcony at the top of the tower. He pushed two shot puts with different weights down at the same time and observed their whereabouts. He found that the big ball and the small ball landed at the same time, instead of falling vertically, but slightly to the east. ? Objects thrown by people from towers or mine mouths are slightly eastward when they land. ? What kind of object will be biased when it falls to the landform? It turns out that when the earth rotates, the circular arcs formed by the top of the tower and the tower base are different in size. The circular arc at the top of the tower is larger than that at the base of the tower, and the linear velocity is also larger. In this way, an object falling freely from the top of the tower will keep its original speed according to the law of inertia. Therefore, the object will walk in front of the tower bottom and finally deviate a little. The higher the tower is, or the closer the test center is to the equator, the more obvious the deviation will be. ? In the center of the hall of the Beijing Planetarium, there is a Foucault pendulum that proves the rotation of the earth. The swing direction rotates for about 37 hours 15 minutes, except for the one upstairs.