What Is a Terrestrial Planet?

Earth (Earth) is one of the eight major planets in the solar system, and is ranked third from near to far from the sun. The earth rotates from west to east while orbiting the sun. Currently 4 to 4.6 billion years old, ^[1] it has a natural satellite, the moon, and the two form a celestial system, the Earth-Moon system. 4.6 billion years ago originated in the primitive solar nebula.

[dì qiú]

Earth (Earth) is one of the eight major planets in the solar system, and is ranked third from near to far from the sun. The earth rotates from west to east while orbiting the sun. Currently 4 to 4.6 billion years old, ^[1] it has a natural satellite, the moon, and the two form a celestial system, the Earth-Moon system. 4.6 billion years ago originated in the primitive solar nebula.

The Earth's equatorial radius is 637.8137 kilometers, the polar radius is 6356.752 kilometers, the average radius is about 6371 kilometers, and the circumference of the equator is about 40076 kilometers. The surface area of the earth is 510 million square kilometers, of which 71% are oceans and 29% are terrestrial. The earth looks blue in space.

There are core, mantle, and crust structures inside the earth, and there are hydrospheres, atmospheres, and magnetic fields outside the earth. The earth is the only celestial body known to exist in the universe at present, and it is the home of millions of creatures including humans. ^[1]

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When small celestial bodies hit the earth, we can do these things. . . . . . 2018-07-13 13:07

Please imagine this scenario: One day observations confirmed that an asteroid is flying towards the earth and is about to hit the earth. How will you react? At this time, the world's major space powers have reached a consensus and must work together to prevent the collision. And how things will develop in the future depends largely on how much time we have to deal with before the impact occurs. Of all the options, none of them is easy, and at least one of them will require humans to use nuclear bombs. ... more

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2018-09-07 22:09 God's perspective overlooking the earth2018-09-07 22:09

Even if there is Martian life in the liquid water lake, it is only the lingering gasp under the wings of death. This is not like the truth of life near Mars, but more like the future of the earth. Because human beings have also reshaped the direction of the earth in millions of years. ... more

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Content finishing: Encyclopedia team

Chinese name

Earth

Foreign name

Earth

nickname

Gaia

Classification

planet

Quality

5.965 × 10 ^ 24kg

Average density

5507.85kg / m³

Diameter

12756 km

surface temperature

15 degrees Celsius (59 degrees Fahrenheit)

Escape speed

11.2km / s (39,600 km / h)

Albedo

0.367

Rotation period

23h56min4s

Right

Undefined

Declination

+ 90 °

Semi-major axis

149,597,887.5km

Eccentricity

0.016710219

Revolution cycle

One year (365.24219 days)

Orbit inclination

0 (7.25 ° to the solar equator)

Volume

1.0832073 × 10 ^ 12km³

Apical distance

152,097,701.0km

Perihelion distance

147,098,074.0km

Orbital perimeter

924,375,700.0km

Perihelion point angle

114.20783 °

Orbit semi-minor axis

149,576,999.826km

Average revolution speed

29.783km / s (107,218km / h)

Maximum revolution speed

30.287km / s (109,033km / h)

Minimum revolution speed

29.291km / s (105,448km / h)

Wei Xing

Moon

Cosmic velocity

11.186km / s (39600km / h)

Stellar day

0.997258d (23.934h)

Equatorial circumference

40,075.13km

aspect ratio

0.9966471

Equatorial rotation rate

465.11m / s

Earth birth and evolution

Main article: Earth history, continental drift hypothesis

4.6 billion years ago, the earth was born. The evolution of the earth can be roughly divided into three stages.

The solar system 5 billion years ago (4 photos)

The first stage is the period of the formation of the Earth's sphere. Its time limit is approximately 4600 to 4200 Ma. The Earth, born 4.6 billion years ago, is very different from the 21st century. According to scientists, the Earth began as a glowing sphere of hot liquid material, mainly magma. Over time, the temperature of the earth's surface continues to drop, and solid earth's cores gradually form. The dense material moves to the center of the earth, and the low-density material (rocks, etc.) floats on the surface of the earth. This forms an earth whose surface is mainly composed of rocks.

The second stage is the Archean and Proterozoic periods. Its time limit is 4200-543Ma. The earth releases energy from the outside without interruption. The water vapor, carbon dioxide and other gases released by the high temperature magma continue to form a very thin early atmosphere-the primitive atmosphere. With the continuous increase of water vapor in the original atmosphere, more and more water vapor condenses into small water droplets, and then converges into rainwater and falls to the ground. In this way, a primitive ocean was formed.

The third stage is the Phanerozoic period, and its time period is from 543Ma to the present. The period of the Phanerozoic is relatively short, but during this period, the organism and its prosperity, the geological evolution was very rapid, the geological functions are colorful, and the geological bodies are spread all over the world, and they are widely preserved. The main research object of geological science, and established the basic theory and basic knowledge of geology.

Human scientists have been able to reconstruct information about the past of the earth. The material of the solar system originated from 4.5672 billion ± 600,000 years ago, and about 4.54 billion years ago (with an error of about 1%), the earth and other planets in the solar system began to form in the solar nebula, the gas and dust remaining after the sun formed of

Looking at the earth in the universe (21 photos)

Disc-shaped-formed inside. Through the process of accretion, after 10 to 20 million years, the earth has been roughly formed. From the initial molten state, the outer layer of the earth cooled and solidified into a solid crust, and water began to accumulate in the atmosphere. The moon formed later, about 4.53 billion years ago, and a celestial body the size of Mars and about 10% of the Earth's mass (commonly known as Zia) collided with the Earth fatally. Part of the mass of this celestial body is combined with the earth, and part of it is splashed into space, and enough material enters the orbit to form the moon. The released gas and volcanic activity generate the original atmosphere. Water carried by asteroids, larger protoplanets, comets, and outer objects of Neptune increases the earth's water content, and the condensed water produces the ocean. The newly formed sun is only 70% lighter than the sun, but there is evidence that the early oceans were still liquid, which is called the faint young sun fallacy paradox. The combination of the greenhouse effect and higher solar activity raises the temperature of the earth's surface and prevents the ocean from condensing.

There are two main theories that suggest the growth of the continent: steady growth to modern times and rapid growth in early history. Studies have shown that the second theory is more likely. The early crust grew rapidly, followed by a long-term stable continental region. During the last few hundred million years on the time scale, the surface continued to reshape itself, and the continent continued to form and split. Supercontinentes occasionally form on continents that migrate on the surface. About 750 million years ago, the earliest known supercontinent, Rodinia, began to split, and later merged into the Pannosian continent between 600 and 540 million years ago, and finally the Pangu continent, which began to split 180 million years ago. . ^[1]

Geological period

Main article: Geological period

During the evolution of the earth, some astronomical and geological events occur, and the time period of the event is called the geological period.

During the stratigraphic period, major events that occurred in the universe-related space of the earth and in the solar system and the earth have left behind in many aspects of the earth itself, crustal movement, strata, rocks, structures, paleontology, paleomagnetism, glaciers, and paleoclimate. recording.

In different geological periods, the geological effects are different and the characteristics are different.

The history of the earth is divided into: the period of earth formation, the period of crustal formation, the period before entering the solar system, the period of entering the solar system, the period of terrestrial-lunar formation, and the period of nascent formation.

Table of geological periods and characteristics

Geological period			feature	generation (boundary)	universe (Woo)	Years from this year Ma
Enter Into too Yang system Time period	Ground month system shape to make Time period	newborn Time period	This period began when a comet hit the earth. The comet cracked in the solar system, forming an asteroid belt around the sun. The composition of a comet is both rock and ice and the atmosphere. There are various creatures in the ice. During this geological period, the earth added water, the atmosphere, and new biological species. The original organism mutates or evolves.	new Raw generation	Show Raw universe	65
			This period began when the moon was captured by the earth and formed the terrestrial-lunar system. The moon's rotation around the earth changes the gravitational field and magnetic field of the earth. Under the sloshing motion caused by the moon's gravitational force, the outer sphere of the earth rotates, forming movements of the earth and magnetic poles. In the biological world, animals and plants have mutated to form tall trees and large animals.	in Raw generation		230
			This period began when the Earth entered the solar system and became a planet. During this geological period, the earth was illuminated by the sun, forming revolutions and rotations around the sun, and changing day and night. In the interior of the earth, the earth's core or inner sphere is biased in the opposite direction of the gravitational pull of the sun, not at the center of the earth. In the crust, due to the rotation of the earth, a centrifugal force from the poles to the equator is formed; under the action of the gravity of the sun, as the earth rotates from west to east, the crust moves from east to west. Form high mountains, plateaus, valleys and depressions. In the biological world, resurrection begins when bursts occur. With the evolution of the solar system, the Earth s orbital plane when entering the solar system, that is, the angle between the orbital plane and the solar equatorial plane was about 23 ° 26 , and it has evolved to the present day. The incline runs on the track, forming a seasonal change of the year. In rock construction, a large amount of limestone appeared.	ancient Raw generation		540
· Before the solar system			This period is a period of geological time before the Earth's crust has formed before the Earth entered the solar system. This is a geological period without sunlight. In the early part of this period, weathering, erosion, transportation and sedimentation of the crust were strong, high mountains were stripped down, and huge original deposits were deposited in gullies and potholes. Later in this period, crustal activity weakened, and the surface temperature gradually decreased below the freezing point, forming a global glacier.	yuan ancient universe		2500
Crustal formation period			This period is a period of geological time from the beginning of solidification of molten material on the ground to the formation of sedimentary rocks. The molten material solidifies to form a contraction, forming a rift valley valley in the mountains. Cosmic celestial bodies collide, forming large potholes on the surface. As the temperature decreases, the water generated during the solidification of the molten material converges in the Zhangchagou Valley and the large potholes, and the generated gas remains on the earth's surface and forms the atmosphere. The core of the earth captures the unevenness of the cosmic material, and the unevenness of the temperature on the surface of the ground produces atmospheric flow. In this geological period, gullies, high mountains, and large potholes were formed on the surface. With water and the atmosphere, weathering, erosion, and transportation occurred, and sedimentary rocks began to form. Primitive life proteins emerge and evolve prokaryotes (bacteria, cyanobacteria). [2]	too ancient universe		4600
Earth formation period			This period is a period of geological time from the beginning of the capture of molten material by the core to the solidification of molten material on the surface. About 4.6 billion years ago, the core composed of iron-nickel material captured the molten material to form the mantle. The temperature at the contact part of the mantle and the core decreases, forming an internal transition layer. The surface temperature decreases and solidifies, forming an outer transition layer. During this geological period, a layered earth was formed.	beginning ancient universe		> 4600

Geographical features

Earth mass

Main article: Earth mass

Cavendish believes that the mass of the earth is about 5.96 × 10 ^ 24 kg

Astral body (5 photos)

The radius ra = 6378137m6378km, the polar radius rb = 6356752m6357km, the oblateness e = 1 / 298.257, the earth's non-spherical symmetry is ignored, and the average radius r = 6371km. The value of gravity acceleration at a certain sea level at the equator is ga = 9.780m / s ^ 2, the value of gravity acceleration at a certain sea level in the Arctic is gb = 9.832m / s ^ 2, and the global standard value of gravity acceleration is g = 9.807m / s ^ 2, the Earth's rotation period is 23 hours, 56 minutes, and 4 seconds (the stellar day), that is, T = 8.616 × 10 ^ 4s.

Earth temperature

The temperature on the earth's surface is affected by solar radiation. The average global surface temperature is about 15 ° C. In the depths of the ground, where the sun is not visible, the temperature is mainly affected by geothermal heat, which increases with depth. The temperature of the earth's core at the center of the earth is even higher than 6000 ° C, which is higher than the surface temperature of the solar photosphere (5778K, 5500 ° C). The hottest place on the surface of the earth appears in Basra, with a maximum temperature of 58.8 ° C. The "cold pole" of the Earth's northern hemisphere is in Oymyakon in the eastern Siberian mountains. The lowest temperature in January 1961 was -71 ° C. The world's "cold pole" is on the Antarctic continent. At the beginning of 1967, the Russians had recorded a minimum temperature of -89.2 ° C at the East Station.

Geoelectricity

Because the earth rotates from west to east, and the outer part of the geomagnetic field points from the magnetic north pole to the magnetic south pole (that is, the south pole points to the north pole), the ring current formed is opposite to the direction of the earth's rotation, so it is negatively charged.

Earth shape

Main article: Earth shape

During a lunar eclipse, careful observation will reveal that the shadow of the earth projected on the moon is always round; when traveling long distances south or north, you will find that the height of the same star in the sky is different. Some clever ancients have guessed from such clues.

Natural disasters (20 photos)

It has been detected that the earth may be spherical. Ptolemy's geocentric theory also clearly describes the view that the earth is spherical, but it was not until the 16th century that the Portuguese navigator Magellan's fleet completed the first voyage around the world in human history. Sphere.

After long-term precise measurements, scientists have discovered that the earth is not a regular sphere, but an irregular elliptical sphere with slightly flat equator and bulge at the poles. Exaggeratedly, it is a bit like a "pear", called a "pear-shaped body". The Earth's equatorial radius is about 637.8137 km long. This difference is very small compared to the average radius of the Earth. Looking at the Earth from space, it can still be regarded as a regular sphere. If a globe with a radius of 1 meter is made according to this ratio, the equatorial radius is only about 3 millimeters longer than the polar radius, which is difficult to detect by human eyes. Therefore, when making a globe, it is always made into a regular sphere. .

Earth location

This position of the earth in the universe has expanded radically in the last century. At first, Earth was considered the center of the universe, but the understanding of the universe at that time included only those planets and stars that seemed to be fixed on the celestial sphere. The heliocentric theory was widely accepted in the 17th century, and William Herschel and other astronomers later observed that the sun was located in a disk-shaped galaxy composed of stars. By the 20th century, observations of the spiral nebula showed that our Milky Way is just one of the billions of galaxies in the expanding universe. By the 21st century, observable

Earth in the universe

The overall structure of the universe is beginning to become clear-clusters of super galaxies form a huge network of large-scale fibers and voids. Super galaxy clusters, large-scale fibrous structures, and voids are probably the largest coherent structures in the universe. On a larger scale (more than a billion-second gap), the universe is homogeneous, meaning that its parts have, on average, the same density, composition, and structure.

The universe has no "center" or "boundary", so we cannot mark the absolute position of the earth in the entire universe. The earth is at the center of the observable universe because observability is determined by the distance to the earth. At various scales, we can use specific structures as reference frames to give the relative position of the earth. It is still unclear whether the universe is infinite. ^[3]

name	weft	warp
definition	A circle perpendicular to the earth's axis and orbiting the earth	A semicircle connecting the north and south poles and intersecting perpendicularly to the parallel.
Indicate direction	East-west direction.	North-south direction.
length	The length varies and the equator is the longest.	All warp lengths are equal.
shape	Except for poles, weft coils are round	All warp threads are semi-circular.
Starting and ending degrees	0 degrees (0 ° parallel is called the equator) 90 ° N / S	0 degrees (0 ° meridian is called the prime meridian) 180 °
Code	North latitudeN, south latitudeS	East longitudeE, West longitudeW
How to differentiate	Distinguish between south and north latitudes (two methods): 1. The north of the equator (0 ° latitude) is north latitude N, and the south of the equator is south latitude S; 2. Latitude increases north to N, and latitude increases south to S.	Distinguish between east and west longitude (two methods): 1. The east of the prime meridian (0 degree meridian) is east longitude E, and the west of the prime meridian is west longitude W; 2. Longitude increases eastward to east longitude E, and longitude increases westward to west longitude E.
Hemisphere division	Equator points south and north hemisphere	20 ° W and 160 ° E points east and west hemisphere

Terrain and Climate

Earth climate

Main article: Climate

Because the earth's climate has changed dramatically since ancient times and this change will continue to evolve, it is difficult to generalize the earth's climate. Earth and sky

The climate of the earth (3 photos)

Natural disasters related to climate and climate include tornadoes, typhoons, floods, and droughts.

The polar climate is separated by two regions where the temperature difference is not large: the broad tropical climate near the equator and the subtropical climate at slightly higher latitudes. The precipitation patterns also vary greatly in different regions. Areas less than one millimeter a year. ^[4]

Geomorphology

Land and sea distribution

The total area of the earth is about 510072 million square kilometers, of which about 29.2% (14894 million square kilometers) is land, and the remaining 70.8% (3611.2 million square kilometers) is water. The land is mainly in the northern hemisphere, with five continents: Eurasia, Africa, America, Australia and Antarctica, and many more islands. The oceans include the five oceans of the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean and the Southern Arctic Ocean and their ancillary waters. The coastline is 356,000 kilometers.

Extreme altitude

Lowest point on land: Dead Sea-418 m

Lowest point in the world: Mariana Trench-11,034 meters

The highest point in the world: Everest 8,844.43 meters

Earth Human Geography

Main article: World

Earth population

The world's total population is the number of human beings living on the earth in a specific time. According to estimates by the United States Census Bureau, as of January 4, 2013, there were approximately 7,058 million people worldwide. The world population continued to grow after the Black Death in the 15th century. The fastest growth rate of the world population (above 1.8%) appeared in the 1950s. According to world population projections, the world population will continue to grow until 2050.

Geopolitical area

There are 226 countries and regions in the world, 199 countries and 27 regions. Asia (48 countries), Europe (44 countries / 2 regions) Africa (53 countries / 3 regions) Oceania (14 countries / 10 regions) North America (23 countries / 13 regions) South America (12 countries / 1 region).

Earth structure

Earth review

Main article: Earth's sphere

The Earth's sphere is divided into two parts: the outer circle of the earth and the inner circle of the earth. The outer circle of the earth can be further divided into four basic layers, namely the atmosphere, hydrosphere, biosphere and lithosphere; the inner circle of the earth can be further divided into three basic layers, namely the mantle circle, outer nuclear liquid circle and solid inner circle. . In addition, there is an asthenosphere between the outer circle of the earth and the inner circle of the earth. It is a transition zone between the outer circle of the earth and the inner circle of the earth. It is located at an average depth of about 150 kilometers below the ground. In this way, the entire earth includes a total of eight spheres, of which the lithosphere, asthenosphere and the inner circle of the earth together constitute a so-called solid earth. The atmosphere, hydrosphere and biosphere in the outer circle of the earth, and the surface of the lithosphere are generally studied by direct observation and measurement methods. The inner circle of the earth is mainly studied by geophysical methods, such as inversion of seismology, gravity, and high-precision modern geodetic space observations. The distribution of the Earth's spheres has a significant feature, that is, the upper air above and above the surface of the solid earth is basically distributed parallel up and down, and near the surface of the earth, the spheres penetrate and even overlap each other. The biosphere has the most significant performance, followed by the hydrosphere.

Solid earth structure table

Earth Sphere Name				depth (Km)	earthquake P-wave velocity (Km / s)	earthquake Shear wave velocity (Km / s)	Density (g / cm3)	substance status
First level Layered	Secondary Layered		Tradition Layered
outer ball	Crust		Crust	0-33	5.6-7.0	3.4-4.2	2.6-2.9	Solid matter
	outer Over Cross Floor	Outer transition layer (on)	Upper mantle	33-980	8.1-10.1	4.4-5.4	3.2-3.6	section Molten substance
		Outer transition layer (under)	Lower mantle	980-2900	12.8-13.5	6.9-7.2	5.1-5.6	Liquid-solid matter
liquid state Floor	Liquid layer		Foreign core	2900-4700	8.0-8.2	Cannot pass	10.0-11.4	Liquid substance
Inside ball	In Level		Transition layer	4700-5100	9.5-10.3		12.3	Liquid-solid matter
	Earth core		Earth core	5100-6371	10.9-11.2		12.5	Solid matter

Earth's atmosphere

Main article: Atmospheric

The Earth's atmosphere is the outermost layer of gas in the Earth's outer circle, which surrounds the ocean and land. There is no exact upper bound on the atmosphere, and there are still thin gases and elementary particles at altitudes of 2,000 to 16,000 kilometers. Under the ground, there is also a small amount of air in the soil and some rocks, which can also be considered as a component of the atmosphere. The main components of the earth's atmosphere are nitrogen, oxygen, argon, carbon dioxide and trace gases with a proportion of less than 0.04%. The total mass of the Earth's atmosphere is approximately 5.136 × 1021 grams, which is equivalent to 0.86% of the total mass of the Earth. Due to the effect of gravity, almost all of the gas is concentrated at a height of 100 kilometers from the ground, and 75% of the atmosphere is concentrated in the troposphere from the ground to 10 kilometers. According to the distribution characteristics of the atmosphere, the troposphere can be divided into stratosphere, mesosphere, and thermostratigraphy.

Earth hydrosphere

Main article: Hydrosphere

The hydrosphere includes oceans, rivers, lakes, swamps, glaciers, and groundwater. It is a continuous but irregular layer. Looking at the earth from an altitude of tens of thousands of kilometers from the earth, we can see the white clouds formed by water vapor in the earth's atmosphere and the blue ocean covering most of the earth, which makes the earth a "blue planet." The total mass of the earth's hydrosphere is 1.66 × 10 ^ 24g, which is about 1 \ 3600 of the total mass of the earth. The mass of ocean water is about 35 times that of terrestrial water (including rivers, lakes and surface rock pores and soil). If there is no undulation in the solid part of the entire earth, the world will be evenly covered by a layer of water up to 2600 meters deep. The atmosphere and hydrosphere combine to form a fluid system on the surface.

Earth biosphere

Main article: Biosphere

Due to the existence of the earth's atmosphere, the earth's hydrosphere, and the surface minerals, a natural environment suitable for living organisms has been formed under the appropriate temperature conditions on the earth. People usually refer to living things, including living things, including plants, animals, and microorganisms. It is estimated that there are about 400,000 species of plants, 1.1 million species of animals, and at least 100,000 species of microorganisms. According to statistics, there have been about 500 to 1 billion species of organisms that have existed in the history of geology. However, during the long evolution of the earth, most of them have become extinct. Existing creatures live in the upper part of the lithosphere, the lower part of the atmosphere, and all of the hydrosphere, forming a unique layer on the earth, called the biosphere. The biosphere is a unique layer of all planets in the solar system that exists only on Earth.

Earth lithosphere

Main article: Lithosphere

The earth's lithosphere cannot be directly observed except for its surface morphology. It is mainly composed of the earth's crust and the top of the upper mantle in the mantle circle. It passes from the solid earth surface down through the first discontinuity surface (moho surface) shown by the seismic wave at nearly 33 kilometers and extends to the asthenosphere. until. The lithosphere is uneven in thickness, with an average thickness of about 100 kilometers. Because the lithosphere and its surface morphology are closely related to modern geophysics and geodynamics, the lithosphere is the most studied, detailed and thorough solid earth part in modern earth science. Since the ocean floor occupies as much as two-thirds of the total surface area of the earth, and the ocean basin accounts for about 45% of the total ocean floor area, with an average water depth of 4,000 to 5,000 meters, a large number of submarine volcanoes are distributed in the ocean basin. Surrounded by vast seabed hills. Therefore, the main surface morphology of the entire solid earth can be considered to be composed of ocean basins and continental platforms. The study of them constitutes a "global tectonics" theory that is directly related to lithosphere structure and geodynamics.

Earth Asthenosphere

Main article: Asthenosphere

In the upper mantle, about 100 kilometers below the earth's surface, there is an obvious low-velocity layer of seismic waves. This was first proposed by Gutenberg in 1926 and is called the asthenosphere. It is located in the upper part of the upper mantle, namely B Floor. Below the ocean floor, it is located below a depth of about 60 kilometers; in the continental region, it is located below a depth of about 120 kilometers, with an average depth of about 60 to 250 kilometers. Modern observations and research have confirmed the existence of this asthenosphere. It is because of the existence of this asthenosphere that the outer circle of the earth is distinguished from the inner circle of the earth.

Earth's mantle circle

Main article: Mantle circle

In addition to a significant discontinuity (referred to as the Moho) at about 33 kilometers below the ground, the seismic wave belongs to the mantle circle under the asthenosphere to the interface at a depth of about 2900 kilometers inside the earth. Because the outer core of the earth is liquid, the S wave of the seismic wave in the mantle cannot propagate through this interface in the outer core. The velocity of the P-wave curve at this interface also decreases sharply. This interface was discovered by Gutenberg in 1914, so it is also called the Gutenberg surface, and it forms the interface between the mantle circle and the outer nuclear fluid circle. The entire mantle circle consists of the upper mantle (33 to 410 km), the D layer of the lower mantle (depth of 1000 to 2700 km), and the D layer of the lower mantle (depth of 2700 to 2900 km). Geophysical studies show that D There is a strong lateral heterogeneity in the layer. The degree of heterogeneity is even comparable to that of the rock layer. It is not only a thermal boundary layer that transfers heat from the core to the mantle, but also a chemical layer with a different chemical composition from the mantle .

Extraterrestrial nuclear liquid circle

Main article: Outer nuclear fluid circle

Below the mantle circle is the so-called outer nuclear liquid circle, which is located at a depth of about 2900-5120 kilometers below the ground. The entire outer nuclear liquid circle may be basically composed of a liquid with a very low dynamic viscosity, of which the depth of 2900 to 4980 kilometers is called the E layer and is completely composed of liquid. The 4980-5120 km depth layer is called the F layer, and it is a very thin transition layer between the outer nuclear liquid circle and the solid inner core circle.

Earth solid core circle

Main article: Solid inner circle

The closest to the center of the earth's eight circles is the so-called solid core circle, which is located at the center of the earth at 5,120-6371 kilometers, also known as the G layer. According to the detection and research of seismic wave velocity, the G layer is proved to be a solid structure. The inner layer of the earth is not homogeneous. The average earth density is 5.515 g / cm3, while the density of the earth's lithosphere is only 2.6 to 3.0 g / cm3. Therefore, the density inside the earth must be much larger, and the density also changes significantly with increasing depth. The temperature inside the earth rises with depth. According to recent estimates, the temperature is 1300 ° C at a depth of 100 km, and 2000 ° C at 300 km. At the boundary between the mantle circle and the outer nuclear liquid circle, it is about 4000 ° C, and the temperature at the center of the earth is 6000 ° C the above.

Beautiful earth

Earth movement

Earth rotation

Main article: Earth rotation

The earth has a rotation from west to east about the rotation axis, and the average angular velocity is 15 degrees per hour. On Earth's equator, the linear speed of rotation is 465 meters per second. The phenomenon of various celestial bodies rising and falling in the sky is a reflection of the rotation of the earth. The earliest people used the rotation of the earth as the benchmark for measuring time. Since the 20th century, due to the development of astronomical observation technology, people have found that the rotation of the earth is uneven. In 1967, an atomic time more accurate and stable than the rotation of the earth began. Due to the establishment and adoption of atomic time, various changes in the rotation of the earth have been discovered successively. Astronomers have been aware of long-term slowing, irregular changes, and periodic changes in the Earth's rotation speed.

The cyclical changes of the earth's rotation mainly include the changes of the annual cycle, the changes of the monthly cycle, the half-month cycle, and the changes of the near-sunday and half-weekday cycles. The annual cycle change, also known as seasonal change, was discovered in the 1930s. It manifests itself as a slow earth rotation in spring and an accelerated earth rotation in autumn, with half-year cycles. The amplitude of the annual change is 20 to 25 milliseconds, which is mainly caused by seasonal changes in wind. The amplitude of the semi-annual change is 8-9 milliseconds, which is mainly caused by the solar tide. In addition, the amplitude of the monthly and half-moon cycle changes is about ± 1 millisecond, which is caused by the moon's tidal force. The earth's rotation has Sunday and semi-sunday changes that have only been discovered and confirmed in the last ten years. The amplitude is only about 0.1 milliseconds, which is mainly caused by the moon's weekly and semi-weekly tidal effects. ^[5]

Earth revolution

Main article: Earth revolution

The orbit of the earth's revolution is elliptical. The half-length diameter of the orbit is 149597870 km, the eccentricity of the orbit is 0.0167, and the average orbit velocity of the orbit is 29.79 kilometers per second. The intersection angle of the orbital plane (ecliptic plane) and the earth's equatorial plane is 23 ° 27 ', called yellow

Overlooking the Earth from the International Space Station

Chek Lap Kok. The rotation of the earth produces day and night changes on the earth. The rotation of the earth and the existence of the yellow-red intersection angle cause the alternation of the four seasons.

From the earth's perspective, the sun moves counterclockwise along the ecliptic, and there are two intersections between the ecliptic and the equator on the celestial sphere at 180 °. The point at which the sun passes the equator from south to north of the equator along the equator is called the vernal equinox, and The vernal equinox is separated by 180 ° and is called the autumn equinox. The sun passes the vernal equinox and autumn equinox each year on the vernal equinox (around March 21) and the autumn equinox (around September 23). For people living in the northern hemisphere, when the sun passes the vernal equinox and autumn equinox respectively, it means that it is spring or autumn. The point at which the sun reaches the northernmost point through the vernal equinox is called the summer solstice point, and the other point that differs by 180 ° is called the winter solstice point. The sun passes the summer solstice and winter solstice around June 22 and December 22, respectively. Similarly, for people living in the northern hemisphere, when the sun is near the summer solstice and winter solstice points, it has entered the summer and winter seasons in an astronomical sense. The above situation is exactly the opposite for people living in the southern hemisphere. ^[5]

Earth Age Division

Serial number	Prehistoric times	Till now Unit: billion years	Main event
1	Pleistocene, Cretaceous	45.7	Earth appears
2	Native generation	41.5	The first organism on the earth-bacteria
3	Bacchus	39.5	Archaea appear
4	Early Rain Haidai	38.5	Oceans and other waters appear on Earth
5	Archaean, Archaean	38	Earth's lithosphere, hydrosphere, atmosphere and life formation
6	Ancient Archean	36	Blue-green algae appear
7	Middle Archeology	32	Further development of prokaryotes
8	New Archaic	28	First ice age
9	Proterozoic, Chengtian Period	25
10	Stratified period	twenty three
11	Orogenic	20.5
12	Paleoproterozoic, consolidation	18
13	Caprock	16
14	Extension period	14
15	Middle Proterozoic, Narrow Zone	12
16	Stretching period	10	Rodinia ancient land formation
17	Ice age	8.50	Snowball event
18	Neoproterozoic, Ediacaran	6.3	Multicellular organisms emerge
19	Phanerozoic, Paleozoic, Cambrian	5.42	Cambrian life explosion
20	Ordovician	4.883	Fish emerges; marine algae flourishes
twenty one	Silurian	4.437	Terrestrial naked fern plants appear
twenty two	Devonian	4.16	Fish prosperity; amphibians appear; insects appear; gymnosperms appear; stone pine and equisetum
twenty three	Carboniferous	3.592	Insect boom; reptiles emerge; coal forest
twenty four	Permian	2.99	Permian extinction event, 95% of biological extinction on earth; Pangu continent formed
25	Mesozoic, Triassic	2.51	Dinosaurs appear; oviparous mammals appear
26	Jurassic	1.996	Marsupial mammals appear; birds appear; gymnosperms flourish; angiosperms appear
27	Cretaceous	0.996.	Prosperity and extinction of dinosaurs, Cretaceous-Tertiary extinction events, 45% of biological extinction on earth, mammals with placenta
28	Tertiary	unknown	Flora and fauna are close to modern
29	Quaternary	0.0621	Human emergence

Earth globe age

In the 21st century, scientists reconfirmed the age of the earth, thinking that the earth was born much later than the time of the solar system, with a span of about 150 million years, which is much later than the previously thought of 30-45 million years. Earlier, scientists calculated the age of the solar system by using the formula of the age of the solar system to be 5.568 billion years ago, and the age of the earth was about 3 billion to 4.5 billion years later than the solar system, about 2.548 billion years ago. In 2007, Swiss scientists revised this data and thought that the Earth would be created 62 million years after the formation of the solar system.

Scientists generally calculate the age of the earth and the moon by using two radioactive elements, thorium 182 and tungsten 182, which are isotopic elements. The decay period of thorium 182 is 9 million years after the isotope is tungsten 182, and tungsten 182 is one of the components of the earth's core. Scientists believe that when the earth was formed, almost all the elements of thorium 182 had decayed into tungsten 182. Only a very small amount exists, and it is this small amount of plutonium 182 that can help scientists estimate the true age of the earth. A professor at the Niels Institute said: "It takes 5-6 billion years for all thorium to decay completely to tungsten, and it will sink in the core of the earth, and new evidence indicates that the Earth and the lunar upper mantle contain more elements than The solar system, and the estimated time is about 150 million years "

Earth earth satellite

Main article: Earth satellite, moon

The earth has a moon, the moon is commonly known as the moon, and it is also called the overcast. It is the only natural satellite in the solar system. The moon is the most obvious example of a natural satellite. In the solar system, except for Mercury and Venus, there are natural satellites in other planets. Moon diameter about 3476

Earth (19 photos)

Kilometers are 1/4 of the earth. Its volume is only 1/49 of the earth, and its mass is about 735 billion tons, which is equivalent to 1/81 of the mass of the earth. The gravity on the surface of the moon is almost 1/6 of the gravity of the earth. ^[6]