Questions about the earth!

The ranking of the solar system is this:

Sun | Mercury Venus Earth Mars Jupiter Uranus Neptune Pluto

The earth is composed of a concentric sphere with uneven material distribution, including the crust, mantle and core. The crust thickness varies, with an average thickness of about 17 km. The upper layer is granite and the lower layer is basalt. The temperature and pressure inside the earth increase with the increase of depth. According to the test, most rocks in the crust are less than 2 billion years old, and the earth has been formed for about 4.6 billion years, which shows that the rocks that make up the crust are not the original crust of the earth, but the materials inside the crust are formed through volcanic activities and orogenic activities.

The mantle is about 2900 kilometers thick, the upper mantle is mainly olivine, and the lower mantle is a solid material with certain plasticity. The average thickness of the core is about 3400 kilometers, and the outer core is liquid and movable. The inner core is solid, mainly composed of metal elements such as iron and nickel. The center density is13g per cubic centimeter, the highest temperature can reach about 5000℃, and the highest pressure can reach 3.7 million atmospheres.

The earth also includes the atmosphere, hydrosphere and biosphere. There is no obvious boundary between these three circles. They penetrate and influence each other, and with the participation of the sun and human life, the whole earth is full of vitality.

The ocean area of the earth accounts for 7 1% of the earth, and the land area accounts for 2 1%.

The formation of the earth: the formation of the primitive earth

Before the formation of the earth, many asteroids in the universe revolved around the sun, and these planets collided with each other to form the original earth. At that time, the earth was still a fiery fireball. With the gradual reduction of collisions, the earth began to cool slowly from the outside to the inside, resulting in a thin crust-the crust. At this time, the interior of the earth is still in a state of high temperature. A large number of gases are ejected from the earth's interior,

There is a lot of water vapor in it, forming the atmosphere around the earth. The earth is not too close to the sun to evaporate water vapor, and the earth itself has enough gravity to pull the atmosphere, so the earth will have a unique atmospheric environment.

After the formation of the atmosphere, it began to rain, forming a primitive ocean.

About 4.7 billion years ago, dust gathered in the universe, forming the earth and other planets in the solar system. At that time, the air did not contain oxygen, but it contained a lot of carbon dioxide (carbonic acid gas) and nitrogen.

The original earth is very small, but it is constantly hit by dust and small stars in the universe, and its volume is constantly increasing. Moreover, the energy and temperature accumulated during the impact process continue to rise and finally melt into liquid.

Soon, the number of star collisions decreased, and the temperature of the earth's surface decreased, forming the crust. This is the surface of the earth today. However, the magma inside the earth keeps spewing, forming a large number of volcanoes. The water vapor in volcanic ash cools and condenses into water, thus forming the ocean.

The formation of the primitive earth

Before the formation of the earth,

There are many asteroids orbiting the sun in the universe.

These planets collided with each other and formed the primitive earth.

At that time, the earth was still a fireball of moxibustion heat.

As collisions gradually decrease,

The earth began to cool slowly from the outside to the inside,

A thin shell-the earth's shell,

At this time, the interior of the earth is still in a hot state.

The formation of the atmosphere and oceans

A large number of gases are ejected from the earth's interior,

There is a lot of water vapor,

These water vapors form the atmosphere around the earth.

The distance between the earth and the sun is not so close that water vapor is evaporated by the sun.

The earth itself has enough gravity to attract the atmosphere,

This is why the earth has a unique atmospheric environment.

After the atmosphere formed, it began to rain.

And formed a primitive ocean.

Formation of Volcano: 1943 In February, people saw a rare and surprising phenomenon in a cornfield in Mexico: a volcano was forming there at that time. Three months later, a volcanic pile about 300 meters high was formed. Two towns were destroyed, and scattered ash residue destroyed a large area.

What are volcanoes made of? Below the surface, the deeper the surface, the higher the temperature. At a depth of about 32 kilometers from the ground, the temperature is high enough to melt most rocks.

When rocks melt, they expand and need more space. In some parts of the world, mountains are rising. The pressure under these rising mountains is decreasing, and a pool of lava (also known as "magma") may form under these mountains.

This substance rises along the cracks caused by the uplift. When the pressure in the lava dome is greater than the pressure on the top of the rock above it, a volcano will form outward.

When erupting, hot gas, liquid or solid substance suddenly comes out. These substances piled up around the opening to form a conical hill. "Crater" is a depression at the top of the volcanic cone, and its opening leads to the surface. This cone-shaped mountain is the product of volcanic formation. The material ejected by the volcano is mainly gas, but it also ejects a lot of volcanic rocks and solid materials such as slag and ash.

In fact, volcanic rocks are magma erupted by volcanoes. When the magma rises to a height close to the surface, its temperature and pressure begin to drop, and physical and chemical changes have taken place, and the magma becomes volcanic rock.

Number of revolutions:

Produce changes in the four seasons

Earth revolution

The earth revolves around the sun.

Characteristics of the earth's revolution

Just as the rotation of the earth has its unique regularity, so does the revolution of the earth. These laws are shown in the following aspects: the earth orbit, the angle between the earth orbit plane and the ecliptic, the period of revolution of the earth and the revolution speed of the earth.

1. The orbit and direction of the earth's revolution

During the revolution of the earth, every point on the route it passes is on the same plane and forms a closed curve. The closed curve that the earth takes in the process of revolution is called earth orbit. If we regard the earth as a particle, then the orbit of the earth actually refers to the orbit of the center of the earth.

Strictly speaking, the center of the earth's revolution is not the center of the sun, but the common center of mass of the earth and the sun. Not only the earth is rotating around this common center of mass, but also the sun is rotating around this point. However, the sun is the central celestial body in the solar system, and the earth is just an ordinary planet in the solar system. The mass of the sun is 330 thousand times that of the earth, and the center of mass of the sun and the earth is only 450 kilometers away from the center of the sun. Compared with the radius of the sun of about 700 thousand kilometers, this distance is really insignificant, even smaller than the distance between the sun and the earth of 65.438+0.5 billion kilometers. Therefore, it is very close to the actual situation to regard the revolution of the earth as the movement of the earth around the sun (center).

The shape of the earth's orbit is an ellipse close to a perfect circle, and the sun is located at a focal point of the ellipse. An ellipse has a semi-major axis, a semi-minor axis and a semi-focal length, which are denoted by A, B and C respectively, where A is the distance from both ends of the minor axis to the focus (F 1, F2).

There is such a relationship between the semi-focal length and the semi-long axis and the flat short axis:

Namely c2=a2-b2

The ratio c/a of the semi-focal length c to the semi-major axis a is the eccentricity of the ellipse, which is expressed by e, that is, e=c/a,

Eccentricity is a quantitative representation of elliptical shape, and the value of e is greater than 0 and less than 1. The closer the ellipse is to the circle, the smaller the value of e is, that is, it is close to 0; On the contrary, the flatter the ellipse, the greater the e value. It is determined that the semi-major axis A of the earth's orbit is 149600000 km, and the semi-minor axis B is 149580000 km. According to this data, the eccentricity of the earth's orbit is calculated as follows:

It can be seen that the earth's orbit is very close to a circle.

Because the earth's orbit is elliptical, as the earth rotates around the sun, the distance between the sun and the earth is constantly changing. The point on the earth's orbit closest to the sun, that is, the end of the long wheelbase of the elliptical orbit close to the sun, is called the perihelion. In modern times, the date when the earth passes the perihelion is around the beginning of 1 month every year. At this time, the distance between the earth and the sun is about 147 100000 kilometers, which is usually called the nearest distance. The point in the earth's orbit farthest from the sun, that is, the long wheelbase end of the elliptical orbit far from the sun, is called the apohelion. In modern times, the date of the perihelion of the earth is about the beginning of July every year. At this time, the earth is about 152 100000 kilometers away from the sun, which is usually called the distance from the sun. The average value of short distance and long distance is 1 49.6 million kilometers, which is the average distance from the sun to the earth, that is,1astronomical unit.

According to ellipse circumference's calculation formula:

L=2πα( 1-0.25×e2)

According to calculation, the total length of the earth's orbit is 940,000,000 kilometers.

The revolution direction of the earth is consistent with the rotation direction. Seen from the yellow North Pole, it rotates counterclockwise, that is, from west to east. This is consistent with the revolution direction of other planets and most satellites in the solar system (as shown in Figure 3- 17).

2. The annual apparent motion of the sun

The revolution of the earth is discovered from the annual apparent movement of the sun. In order to explain the annual apparent motion of the sun, we first analyze the relationship between the moving point and the fixed point.

If moving point A moves in a circle around fixed point B, the direction is as shown in Figure 3- 18. Then at the fixed point B, the trajectory of point A is a circle, and the movement direction of point A is counterclockwise. In this case, from the driving point A, the motion characteristics of the fixed point B are exactly the same, and the trajectory of the point B is also circular, and the motion direction is also counterclockwise. But the movement of A around B is true, and the movement of B around A is apparent, which is an intuitive reflection of the movement of A around B. ..

The characteristics of the earth's revolution around the sun and the apparent motion of the sun seen by observers on the earth are the same as those mentioned above. As shown in figure 3- 19, although the actual situation is that the earth revolves around the sun, as an observer on the earth, he can only feel the movement of the sun relative to the starry sky. The trajectory plane of this movement coincides with the orbital plane of the earth, and its direction, speed and period are the same as those of the earth. The motion of the sun relative to the starry sky is a kind of apparent motion, which is called solar annual apparent motion. The annual apparent motion of the sun is actually a reflection of the earth's revolution on the celestial sphere.

3. Earth's orbital plane and left and right angles.

As mentioned earlier, every point in the earth's orbit is on the same plane, and this plane is the earth's orbital plane. The orbital plane of the earth appears as the ecliptic plane on the celestial sphere, which is on the same plane as the annual apparent motion route of the sun.

The earth's rotation and revolution are simultaneous. On the celestial sphere, rotation is represented by celestial axis and celestial equator, and revolution is represented by yellow axis and ecliptic. The celestial equator is on one plane and the ecliptic is on another. The planes of these two concentric circles form an included angle of 23 26', which is called the ecliptic angle (as shown in Figure 3-20).

The existence of the ecliptic angle actually means that the axis of rotation is inclined to the earth's orbital plane during the earth's revolution around the sun. Since the earth axis is perpendicular to the equatorial plane of the celestial sphere, the intersection angle between the earth axis and the earth orbital plane should be 90-23 26', that is, 66 34'. No matter where the earth rotates, this tilt remains the same.

During the revolution of the earth, the spatial orientation of the earth axis has not changed obviously for a long time. At present, the North Pole points to Alpha Star in Ursa minor, that is, near Polaris, which

It is the position of the north pole of the celestial sphere. That is to say, the earth axis moves in parallel during the revolution, so no matter where the earth revolves, the angle between the earth axis and the earth orbit plane is constant, and the angle between yellow and red is also constant.

The existence of the ecliptic angle also shows the deviation between the ecliptic pole and the celestial pole, that is, the yellow north pole (or yellow south pole) and the celestial north pole (or celestial south pole) deviate from 23 26' on the celestial sphere.

Most of the globes we see have an inclined axis of rotation, which is inclined at an angle of 66 34' with the desktop (representing the earth's orbital plane), while the equatorial plane of the globe is at an angle of 23 26' with the desktop, which is an intuitive embodiment of the angle between the yellow and the pond.

4. Earth revolution and precession period.

The time for the earth to revolve around the sun is the period of revolution of the earth. Generally speaking, the revolutionary period is one year. Because the period of the solar annual apparent motion is the same as that of the earth's revolution, the period of the earth's revolution can be measured by the solar annual apparent motion. Observers on the earth observe that the interval between the continuous passage of the sun through a certain point on the ecliptic is one year. Because the selected reference points are different, the length of "year" is also different. The commonly used cycle units are sidereal year, tropic year and perihelion year.

The sidereal year of the earth's rotation is a sidereal year. This periodic unit is obtained with the star as the reference point. In a sidereal year, starting from the center of the sun, the center of the earth takes a star as the background, starts from a certain point, orbits the sun once, and then returns to the same point in the sky; Seen from the center of the earth, the center of the sun starts from a certain point on the ecliptic, is fixed relative to the stars, runs once, and then returns to the same point on the ecliptic. Therefore, from the perspective of the geocentric celestial sphere, the length of a sidereal year is the time interval when the sun center passes the same star twice in succession on the ecliptic.

The sidereal year is obtained with a star as the reference point, so it is the time when the earth rotates 360 degrees, and it is also the real period of the earth's revolution. In days, its length is 365.2564 days, that is, 365 days, 6 hours and 9 minutes 10 second.

The vernal equinox period of the earth's revolution is the Tropic of Cancer. This periodic unit is obtained with vernal equinox as the reference point. In a tropical year, starting from the sun center, the center of the earth has arrived in vernal equinox twice in a row; Seen from the center of the earth, the sun center has reached the vernal equinox twice in a row. From the point of view of the geocentric celestial sphere, the length of a tropic year is the time interval between two consecutive vernal equinoxes, which depends on the ecliptic.

The vernal equinox is the intersection of the ecliptic and the celestial equator. Its position on the ecliptic is not fixed, and it moves 50 ″ .29 to the west every year. In other words, the vernal equinox is a moving point in a year, and its moving direction is from east to west, which is clockwise. The direction of the sun on the ecliptic is from west to east, that is, counterclockwise. These two directions are opposite. Therefore, depending on the center of the sun, the angle taken by the vernal equinox for two consecutive times is not 360, but 360-50.29, that is, 359 59' 9.71,which is the angle of the earth's revolution in a tropic year. Therefore, the tropic year is not the real cycle of the earth's revolution, but only the time required for the earth to rotate at an angle of 359 59' 9 ".71,that is, 365.2422 days, that is, 365 days, 5 hours, 48 minutes and 46 seconds.

The perihelion period of the earth's revolution is perihelion year. This periodic unit is obtained by taking the perihelion of Earth orbit as the reference point. In a perihelion year, the center of the earth (or the apparent sun center) passes through the perihelion of the earth's orbit twice in a row. Because perihelion is a moving point, its moving direction on the ecliptic is from west to east, that is, it is the same as the direction of the earth's revolution (or the direction of the apparent motion of the solar year), and the annual moving amount is11÷÷, so the perihelion year is not the real cycle of the earth's revolution, and the angle of the earth's revolution in a perihelion year is 360+65430.

Only the sidereal year is the real cycle of the earth's revolution. In the following chapters, we will learn that the tropic year is the cycle of the earth's cold and heat, that is, the cycle of the four seasons, which is closely related to human life and production. The tropical year is slightly shorter than the sidereal year, 20 minutes and 24 seconds shorter each year, which is called precession in astronomy.

Why does vernal equinox move westward by 50.29 every year, leading to precession? This is the result of the precession of the earth axis.

The precession of the earth's axis is closely related to the rotation of the earth, the shape of the earth, the existence of the ecliptic angle and the orbital characteristics of the moon around the earth.

The precession of the earth axis is similar to the swing of the gyro shaft around the vertical line. When the tip gyro is tilted, the rotating shaft draws a conical surface around the axis perpendicular to the ground, and the gyro shaft slowly shakes. This is because the gravity of the earth tends to make it fall, and the inertia of the gyro's own rotating motion makes it unable to stay, so it slowly shakes under the action of gravity. This is the precession of the gyro.

The rotation of the earth is like a giant "top", which keeps spinning. Because of inertia, the earth has been spinning. The shape of the earth itself is similar to an ellipsoid, and the equatorial part is convex, that is, there is an equatorial uplift belt. At the same time, due to the existence of the ecliptic angle, the connection between the sun center and the earth center does not often pass through the equatorial uplift belt. Therefore, the attraction of the sun to the earth, especially to the equatorial uplift belt, is unbalanced. In addition, the orbital plane of the moon's revolution around the earth does not coincide with the ecliptic plane and the equatorial plane of the celestial sphere, but forms an angle of 5 9' with the ecliptic plane, that is to say, the connecting line between the center of the earth and the center of the moon does not often pass through the equatorial uplift zone. Therefore, the attraction of the moon to the earth, especially to the equatorial uplift belt, is also unbalanced. According to the law of universal gravitation, f 1 > F2.

This unbalanced gravity of the sun and the moon tries to make the equatorial plane coincide with the orbital plane of the earth and reach a state of balance. However, the inertia of the earth's rotation keeps it tilted. Therefore, the earth swings under the unbalanced gravity of the moon and the sun. This kind of swing is characterized by the periodic conical motion of the earth axis with the yellow axis as the axis, and the conical radius is 23 26', which is equal to the intersection angle of yellow and red. This movement of the earth axis is called precession of the earth axis. The precession direction of the earth's axis is from east to west, which is opposite to the revolution direction of the earth's rotation, while the precession direction of the gyro is consistent with the rotation direction.

This is because the gyro tends to "topple" and the earth axis tends to "stand upright".

The precession speed of the earth's axis is very slow, with an annual precession of 50.29 and a precession period of 25,800 years.

Due to the precession of the earth's axis, the tilt direction of the earth's equatorial plane in space has changed, resulting in the corresponding change of the celestial equator, which makes the intersection of the celestial equator and the ecliptic-vernal equinox and the equinox move correspondingly on the ecliptic. The movement direction is from east to west, which is opposite to the revolution direction of the earth, and the annual movement angle is 50 ″ .29. Therefore, the length of a year with spring as the reference point is slightly shorter than that with stars as the reference point, which is the reason for precession.

Due to the precession of the earth's axis, the spatial orientation of the earth's north and south poles has changed, making the celestial pole move around the yellow pole with a period of 25800 years. Therefore, the positions of the celestial north pole and the celestial south pole on the celestial sphere are also moving slowly. As shown in Figure 3-24, Polaris was once the alpha star of Draco in 3000 BC. At present, Polaris is near Alpha in Ursa minor. By the year 7000, it will be moved to the vicinity of Alpha Star in Cepheus. By the year 14000, Vega will become the North Star.

Because of the precession of the earth's axis, the celestial pole and vernal equinox move on the celestial sphere, and the celestial coordinate system based on it will inevitably change accordingly. For the equatorial coordinate system, the right ascension and declination of the star will change, and for the ecliptic coordinate system, the yellow longitude of the star will change. But the precession of the earth axis does not change the declination angle, that is, when the earth axis precesses, the included angle between the earth axis and the earth orbit plane is always 66 34'.

It should also be noted that the moving angles of the celestial pole and the vernal equinox caused by the precession of the earth's axis are relatively small, and there will be no big movement for a long time. Therefore, we can still say that the positions of the celestial pole and vernal equinox are unchanged, and the right ascension, declination and yellow longitude of stars can also be roughly considered as unchanged. Catalogs and maps based on this can still be used for a long time.

5. The rotation speed of the earth

The revolution of the earth is a periodic circular motion, so the revolution speed of the earth includes angular velocity and linear velocity. If the sidereal year is used as the period of the earth's revolution, then the average angular velocity of the earth's revolution is 360 degrees per year, that is, after 365.2564 days, the earth will revolve 360 degrees, that is, about 0.986 degrees per day, that is, about 59' 8 "per day. The total length of the earth's orbit is 940 million kilometers, so the average linear speed of the earth's revolution is 940 million kilometers per year, that is, after 365.2564 days, the earth revolves 940 million kilometers, that is, 29.7 kilometers per second, about 30 kilometers per second.

According to Kepler's second law of planetary motion, the revolution speed of the earth is related to the distance between the sun and the earth. The angular velocity and linear velocity of the earth's revolution are not fixed values, but change with the distance between the sun and the earth. When the earth passes the perihelion, the revolution speed is fast, and the angular velocity and linear velocity both exceed their average values. The angular velocity is11'1"/day, and the linear velocity is 30.3km/s; When the earth is at perihelion, the revolution speed is slow, and the angular velocity and linear velocity are lower than their average. The angular velocity is 57 ′11″/day, and the linear velocity is 29.3km/s. Every year, the earth passes through perihelion at the beginning of 65438+ 10 and apohelion at the beginning of July. Therefore, from the beginning of 65438+ 10 to the beginning of July of that year, the distance between the earth and the sun gradually increased, and the revolution speed of the earth gradually slowed down. From the beginning of July to the beginning of 65438+ 10 of the following year, the distance between the earth and the sun gradually narrowed and the revolution speed of the earth gradually accelerated.

We know that the vernal equinox and the autumnal equinox are equally divided on the ecliptic. If the revolution speed of the earth is uniform, then the time required for the sun to run from the vernal equinox to the autumnal equinox should be the same as the time required for the sun to run from the autumnal equinox to the vernal equinox, which is half of the whole year. However, the revolution speed of the earth is uneven, so the time to travel the same distance must be unequal. Depending on the sun from the vernal equinox to the summer solstice to the autumnal equinox, the earth's revolution speed is slow, which takes more than 186 days, which is longer than half of the whole year. This is the summer half year in the northern hemisphere and the winter half year in the southern hemisphere. Relying on the sun from the autumnal equinox to the vernal equinox through the winter solstice, the revolution speed of the earth is relatively fast, which takes 179 days, less than half of the whole year. This is the winter half year in the northern hemisphere and the summer half year in the southern hemisphere. It can be seen that the change of the revolution speed of the earth is the fundamental reason for the unequal length of the four seasons on the earth.

The formation of life on earth: where did life come from? Are there any aliens in the vast universe? These problems have been puzzling the scientific community. Since it has been proved that the most basic substance of life is amino acid, where did the first amino acid on earth come from?

Scientists put forward the following hypothesis: about 654.38+0.2 billion years ago, on the planet in the early days of the birth of the Milky Way, hydrogen and helium occupied the whole space. With the outbreak of early planets, the second generation of planets emerged, releasing a lot of carbon and oxygen from space, thus producing organic molecules, which provided the foundation for life.

About 4.5 billion years ago, the earth wrapped in dust and gas was born. Under the irradiation of sunlight, gases move violently and mix constantly, resulting in a series of changes, and finally form the basic substance of today's organisms-amino acids.

In order to test this hypothesis, American scientists simulated the atmosphere when there was no life on the earth, injected the mixed gas of methane, ammonia and hydrogen into a large vacuum glassware, and then simulated the original natural conditions of lightning and irradiated these mixed gases with electric sparks. After 8 days and nights of repeated actions, the originally colorless mixed gas gradually turned pale red and finally turned deep red. As a result, five important amino acids that make up protein were found in the originally lifeless glassware. That is to say, as long as there is energy radiation, some atoms that make up organic molecules in the universe can be brought together to synthesize amino acids. This great discovery opened the door to the mystery of life and became one of the most important discoveries in the 20th century.

Or where did life come from?

In this world where life and life activities are shining and thriving, everything is so beautiful, but so far, where does life come from? How did it originate? How did it evolve? This is still a mystery that has not been completely solved.

Two theories about the origin of life

There have been two completely different theories about the origin of life since ancient times.

Special creation theory, spontaneous generation theory, panspore theory

The theory of special creation means that God created life at a special moment in the history of the universe. This theory was once dominant, but it was not accepted by scientists. The theory of spontaneous occurrence holds that life can be naturally produced from nonliving matter. For example, frogs can grow out of mud and maggots can grow out of carrion. This theory can't stand scientific criticism because of experimental observation errors. Panspore theory puts forward that the germ of life comes from extraterrestrial space and then grows and develops. However, because microorganisms are attached to meteorites, it is obviously impossible to reach the earth alive, and they will be killed by ultraviolet rays or die due to space vacuum. The panspore theory only shows that life exists in a special planet in space at most, but it still fails to answer the question of the origin of life in the universe.

Chemical evolution theory

187 1 year, Darwin first imagined how life originated, and proposed that "in warm pools of ammonia and phosphate, under the conditions of light, heat and electricity, some protein compounds were formed and made more complicated changes. 1924, the Soviet biochemist A.I. Oparin proposed that life is the result of long-term evolution. 1928, Haldane of Britain put forward: "When ultraviolet rays act on the mixture of water, carbon dioxide and ammonia, various organic substances including sugars are formed. Some of these substances can form protein, which gathered together before the primitive ocean formed hot soup. "1947, bernal proposed that in the primitive ocean rich in organic matter, all kinds of activities can combine with organic matter, and described the ways and methods to make small molecules aggregate to produce life macromolecules. The ideas of the above scholars laid the foundation for the chemical evolution experiment.

The first step in exploring the origin of life

Where does life come from? How did the first life on earth come into being?

Since the myth of God's creation was shattered, there have been two schools of thought about the origin of life: one thinks that life was transplanted from another planet to the earth; Another school thinks that life is the product of the earth itself.

Urey in the United States advocates that life originates from the earth itself. He and his student Miller designed a simulated primitive atmosphere to study whether substances related to life can be produced under natural conditions. Miller uses methane, ammonia, hydrogen and water vapor as strongly reducing gases, simulates lightning strike by spark discharge, and provides energy of 6.27×103 ~ 6.27×104 kj to the gas through one-week discharge. In a typical experiment, 950 mg of methane produces about 200 mg of amino acids, which constitute the protein of life.

196 1 year, Spanish biochemist Oro added hydrogen cyanide and formaldehyde to the primitive atmosphere. The experimental results show that adenine, ribose and deoxyribose are obtained in addition to amino acids, and the parts that constitute life nucleic acid are obtained.

Both RNA and DNA are phosphates. Where does the phosphorus in the structure come from? 1982, according to the research of modern planetary chemistry, Wang Wenqing, a life chemist in China, detected the existence of PH3 in the atmosphere of Jupiter and Saturn, introduced PH3 into the simulated primitive atmosphere, and carried out spark discharge of methane, nitrogen, PH3, ammonia and water vapor, and compared it with the gas-phase discharge of the above systems without PH3. The results of gas chromatography showed that 19 amino acids were produced after discharge in PH3 system. However, under the same discharge conditions, the PH3-free system only produces 6 kinds of amino acids. Wang Wenqing's experiment discovered the catalytic role of PH3 in gas-phase discharge reaction, which was cited by American and Japanese magazines as the first step of the origin of life and an important progress in the production of amino acids by spark discharge.

Recently, Bada, a marine biologist at the University of California, put forward an organ newspaper argument: the first chance of life on earth was born under the thick ice hundreds of millions of years ago. Bada said that when chaos first opened billions of years ago, the surface of the earth was covered with ice, but the core was hot, radiating five times as much heat as today, so the bottom of the ancient ocean was still liquid water, and the seawater under the ice was a hotbed of primitive life. The ice layer plays a shielding role, which makes the organic molecules in seawater accumulate and become more and more concentrated. When a small celestial body hits the earth, the heat generated melts the thick ice layer into a big hole, which makes the organic molecules in the water contact with the atmosphere and form more complex molecules. Soon, the ice layer froze again and these new molecules were sealed. Every time the ice layer is frozen, the amino acids and bases in the "thick soup" are more abundant until life is born.

(According to China Public Science and Technology Network)

As for why the earth is round, in fact, exactly speaking, the earth is an elliptical sphere, so why it is a sphere has been said before.