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Now most people take it for granted that the sun is at the center of the solar system, but the heliocentric concept did not appear immediately. In the II century AD. Claudius Ptolemy proposed a model with the Earth in the center (geocentric). According to his model, the Earth and other planets are stationary, and the sun revolves around them in an elliptical orbit. The Ptolemaic system was considered correct by astronomers and religion for several hundred years. It wasn't until the 17th century that Nicolaus Copernicus developed a model for the structure of the solar system, in which the sun was at the center instead of the Earth. The new model was rejected by the church but gradually gained ground because it provided a better explanation for the observed phenomena. Oddly enough, Copernicus' initial measurements were no more accurate than Ptolemy's, only they made a lot more sense.
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SOLAR SYSTEM The solar system is a group of astronomical bodies, including the Earth, orbiting and gravitationally bound to a star called the Sun. The Sun's retinue includes nine planets, approximately 50 satellites, more than 1000 observed comets, and thousands of smaller bodies known as asteroids and meteorites).
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The Sun The Sun is the central celestial body of the solar system. This star is a hot ball - I myself am close to the Earth. Its diameter is 109 times the diameter of the Earth. It is located at a distance of 150 million km from the Earth. The temperature inside it reaches 15 million degrees. The mass of the Sun is 750 times greater than the mass of all the planets moving around it combined.
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Jupiter Jupiter is the fifth planet from the Sun and the largest planet in the solar system. Jupiter has 16 satellites, as well as a ring about 6 thousand km wide, almost adjacent to the planet. Jupiter does not have a solid surface, scientists suggest that it is liquid or even gaseous. Due to the great distance from the Sun, the temperature on the surface of this planet is -130 degrees.
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Mercury Mercury is the closest planet to the Sun. The surface of Mercury, covered with basalt-type material, is rather dark, very similar to the surface of the Moon. Along with craters (generally less deep than on the Moon), there are hills and valleys. The height of the mountains can reach 4 km. Above the surface of Mercury there are traces of a very rarefied atmosphere containing, in addition to helium, also hydrogen, carbon dioxide, carbon, oxygen and noble gases (argon, neon). The proximity of the Sun causes the surface of the planet to heat up to +400 degrees.
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Saturn Saturn, the sixth planet from the Sun, the second largest planet in the solar system after Jupiter; refers to the giant planets, consists mainly of gases. Nearly 100% of its mass is made up of hydrogen and helium gas. The surface temperature is approaching -170 degrees. The planet does not have a clear solid surface, optical observations are hampered by the opacity of the atmosphere. Saturn has a record number of satellites, about 30 are now known. It is believed that the rings are formed by various particles, potassium, blocks of various sizes, covered with ice, snow, and frost.
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Venus Venus, the second planet from the Sun, is Earth's twin in the solar system. The two planets have approximately the same diameter, mass, density and soil composition. On the surface of Venus, craters, faults, and other signs of intense tectonic processes were found. Venus is the only planet in the solar system whose own rotation is opposite to the direction of its revolution around the sun. Venus has no satellites. In the sky, it shines brighter than all the stars and is clearly visible to the naked eye. The temperature on the surface is +5000, because an atmosphere composed mostly of CO2
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Uranus Uranus, the seventh planet from the Sun, is one of the giant planets. For many centuries, Earth astronomers knew only five "wandering stars" - planets. 1781 was marked by the discovery of another planet, named Uranus, which was the first to be discovered using a telescope. Uranus has 18 moons. The atmosphere of Uranus is mainly composed of hydrogen, helium and methane.
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Earth is the third planet from the Sun. Earth is the only planet in the solar system with an oxygen-rich atmosphere. Thanks to its unique natural conditions in the Universe, it has become a place where organic life originated and developed. According to modern concepts, the Earth was formed approximately 4.6–4.7 billion years ago from a protoplanetary cloud captured by the attraction of the Sun. The formation of the first, most ancient of the studied rocks took 100–200 million years. ____
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Based on seismic studies, the Earth is conventionally divided into three regions: crust, mantle and core (in the center). The outer layer (crust) has an average thickness of about 35 km. To a depth of about 35 to 2885 km, the Earth's mantle extends, which is also called the silicate shell. It is separated from the bark by a sharp border. Another boundary between the mantle and the outer core detected by seismic methods is located at a depth of 2775 km. Finally, at depths above 5120 km there is a solid inner core, which accounts for 1.7% of the Earth's mass.
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The Earth rotates around its own axis in 23 hours 56 minutes 4.1 seconds. The linear velocity of the Earth's surface at the equator is about 465 m/s. The axis of rotation is inclined to the plane of the ecliptic at an angle of 66 ° 33 "22". This tilt and the annual revolution of the Earth around the Sun determine the change of seasons, which is extremely important for the Earth's climate, and its own rotation - the change of day and night.
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Neptune Neptune is the eighth planet from the Sun. It has a magnetic field. Astronomers believe that below the atmosphere, at a depth of about 10,000 km, Neptune is an "ocean" made up of water, methane and ammonia. There are 8 satellites moving around Neptune. The largest of them is Triton. This planet is named after the ancient Roman god of the sea. The location of Neptune was calculated by scientists, and only then it was discovered with a telescope in 1864.
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Mars Mars is the fourth planet from the Sun. A qualitatively new level of exploration of Mars began in 1965, when spacecraft began to be used for these purposes, which first circled the planet, and then (since 1971) descended to its surface. The mantle of Mars is enriched in iron sulfide, appreciable amounts of which have also been found in the investigated surface rocks. The planet got its name in honor of the ancient Roman god of war. The change of seasons is noticeable on the planet. Has two satellites.
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Pluto Pluto is the ninth largest planet from the Sun in the solar system. In 1930, Clyde Thombaug discovered Pluto close to one of the regions predicted by theoretical calculations. Pluto's mass, however, is so small that the discovery was made by accident as a consequence of intensive exploration of the part of the sky to which the predictions had drawn attention. Pluto is about 40 times farther from the Sun than Earth. Pluto spends almost 250 Earth years per revolution around the Sun. Since the discovery, he has not yet managed to make a single complete revolution.
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The most, most, most ... Mercury is the planet closest to the sunPluto is the planet farthest from the sunOn Venus the highest surface temperatureOnly on Earth there is lifeOn Venus, a day is longer than a yearJupiter is the largest planetSaturn has the largest number of satellites Pluto is the smallest planetJupiter is the coldest » The planet Saturn has the most unusual and colorful appearance.
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Test questions What is the largest planet? What is the smallest planet? The planet closest to the sun? The planet on which life exists? The planet that was first discovered with a telescope? Which planet was named after the god of war? Which planet has the brightest rings? A celestial body that radiates light and heat? What planet was named after the goddess of war and beauty? A planet that was discovered “on the tip of a pen”
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Abstract on the topic
"Earth is a planet in the solar system"
1. The structure and composition of the solar system. Two groups of planets
2. Terrestrial planets. Earth-Moon system
3. Earth
4. Ancient and modern explorations of the Earth
5. Exploring the Earth from space
6. Origin of life on earth
7. Earth's only satellite is the Moon
Conclusion
1. The structure and composition of the solar system. two groups of planets.
Our Earth is one of the 8 major planets revolving around the Sun. It is in the Sun that the main part of the matter of the solar system is concentrated. The mass of the Sun is 750 times the mass of all the planets and 330,000 times the mass of the Earth. Under the influence of the force of its attraction, the planets and all other bodies of the solar system move around the sun.
The distances between the Sun and the planets are many times greater than their size, and it is almost impossible to draw such a diagram that would observe a single scale for the Sun, planets and the distances between them. The diameter of the Sun is 109 times larger than the Earth, and the distance between them is about the same number of times the diameter of the Sun. In addition, the distance from the Sun to the last planet of the solar system (Neptune) is 30 times greater than the distance to the Earth. If we depict our planet as a circle with a diameter of 1 mm, then the Sun will be at a distance of about 11 m from the Earth, and its diameter will be approximately 11 cm. The orbit of Neptune will be shown as a circle with a radius of 330 m. drawing from the book of Copernicus "On the circulation of the celestial circles" with other, very approximate proportions.
According to physical characteristics, large planets are divided into two groups. One of them - the planets of the terrestrial group - is the Earth and similar Mercury, Venus and Mars. The second includes the giant planets: Jupiter, Saturn, Uranus and Neptune. Until 2006, Pluto was considered the largest planet farthest from the Sun. Now, together with other objects of similar size - long-known large asteroids (see § 4) and objects discovered on the outskirts of the solar system - it is among the dwarf planets.
The division of the planets into groups can be traced by three characteristics (mass, pressure, rotation), but most clearly by density. Planets belonging to the same group differ insignificantly in density, while the average density of terrestrial planets is about 5 times greater than the average density of giant planets (see Table 1).
Most of the mass of the terrestrial planets is in solid matter. The Earth and other planets of the terrestrial group consist of oxides and other compounds of heavy chemical elements: iron, magnesium, aluminum and other metals, as well as silicon and other non-metals. The four most abundant elements in the solid shell of our planet (lithosphere) - iron, oxygen, silicon and magnesium - account for over 90% of its mass.
The low density of the giant planets (for Saturn it is less than the density of water) is explained by the fact that they consist mainly of hydrogen and helium, which are predominantly in gaseous and liquid states. The atmospheres of these planets also contain hydrogen compounds - methane and ammonia. Differences between the planets of the two groups arose already at the stage of their formation (see § 5).
Of the giant planets, Jupiter is best studied, on which, even in a small school telescope, numerous dark and light stripes are visible, stretching parallel to the planet's equator. This is what cloud formations look like in its atmosphere, the temperature of which is only -140 ° C, and the pressure is about the same as at the surface of the Earth. The reddish-brown color of the bands is apparently due to the fact that, in addition to the ammonia crystals that form the basis of the clouds, they contain various impurities. The images taken by spacecraft show traces of intense and sometimes persistent atmospheric processes. So, for over 350 years, an atmospheric vortex, called the Great Red Spot, has been observed on Jupiter. In the earth's atmosphere, cyclones and anticyclones exist on average for about a week. Atmospheric currents and clouds have been recorded by spacecraft on other giant planets, although they are less developed than on Jupiter.
Structure. It is assumed that as it approaches the center of the giant planets, due to an increase in pressure, hydrogen should pass from a gaseous to a gaseous state, in which its gaseous and liquid phases coexist. At the center of Jupiter, the pressure is millions of times higher than the atmospheric pressure that exists on Earth, and hydrogen acquires the properties characteristic of metals. In the depths of Jupiter, metallic hydrogen, together with silicates and metals, forms a core, which is approximately 1.5 times larger in size and 10–15 times larger in mass than the Earth.
Weight. Any of the giant planets exceeds in mass all the terrestrial planets combined. The largest planet in the solar system - Jupiter is larger than the largest planet of the terrestrial group - the Earth by 11 times in diameter and more than 300 times in mass.
Rotation. The differences between the planets of the two groups are also manifested in the fact that the giant planets rotate faster around the axis, and in the number of satellites: there are only 3 satellites for 4 terrestrial planets, more than 120 for 4 giant planets. All these satellites consist of the same substances, like the planets of the terrestrial group - silicates, oxides and sulfides of metals, etc., as well as water (or water-ammonia) ice. In addition to numerous craters of meteorite origin, tectonic faults and cracks in their crust or ice cover have been found on the surface of many satellites. The discovery of about a dozen active volcanoes on the closest satellite to Jupiter, Io, turned out to be the most surprising. This is the first reliable observation of terrestrial-type volcanic activity outside our planet.
In addition to satellites, giant planets also have rings, which are clusters of small bodies. They are so small that they cannot be seen individually. Due to their circulation around the planet, the rings appear to be continuous, although both the surface of the planet and the stars shine through the rings of Saturn, for example. The rings are located in close proximity to the planet, where large satellites cannot exist.
2. Planets of the terrestrial group. Earth-Moon system
Due to the presence of a satellite, the Moon, the Earth is often called a double planet. This emphasizes both the commonality of their origin and the rare ratio of the masses of the planet and its satellite: the Moon is only 81 times smaller than the Earth.
Sufficiently detailed information will be given about the nature of the Earth in subsequent chapters of the textbook. Therefore, here we will talk about the rest of the planets of the terrestrial group, comparing them with ours, and about the Moon, which, although it is only a satellite of the Earth, by its nature belongs to planetary-type bodies.
Despite the common origin, the nature of the moon is significantly different from the earth, which is determined by its mass and size. Due to the fact that the force of gravity on the surface of the Moon is 6 times less than on the surface of the Earth, it is much easier for gas molecules to leave the Moon. Therefore, our natural satellite is devoid of a noticeable atmosphere and hydrosphere.
The absence of an atmosphere and slow rotation around the axis (a day on the Moon is equal to an Earth month) lead to the fact that during the day the surface of the Moon heats up to 120 ° C, and cools down to -170 ° C at night. Due to the absence of an atmosphere, the lunar surface is subject to constant “bombardment” by meteorites and smaller micrometeorites that fall on it at cosmic speeds (tens of kilometers per second). As a result, the entire Moon is covered with a layer of finely divided substance - regolith. As described by American astronauts who have been on the Moon, and as photographs of the traces of lunar rovers show, in terms of its physical and mechanical properties (particle sizes, strength, etc.), regolith is similar to wet sand.
When large bodies fall on the surface of the Moon, craters up to 200 km in diameter are formed. Craters meter and even centimeter in diameter are clearly visible in the panoramas of the lunar surface obtained from spacecraft.
Under laboratory conditions, samples of rocks delivered by our automatic stations "Luna" and American astronauts who visited the Moon on the Apollo spacecraft were studied in detail. This made it possible to obtain more complete information than in the analysis of the rocks of Mars and Venus, which was carried out directly on the surface of these planets. Lunar rocks are similar in composition to terrestrial rocks such as basalts, norites, and anorthosites. The set of minerals in lunar rocks is poorer than in terrestrial, but richer than in meteorites. Our satellite does not have and never had a hydrosphere or an atmosphere of the same composition as on Earth. Therefore, there are no minerals that can be formed in the aquatic environment and in the presence of free oxygen. Lunar rocks are depleted in volatile elements compared to terrestrial ones, but they are distinguished by an increased content of iron and aluminum oxides, and in some cases titanium, potassium, rare earth elements and phosphorus. No signs of life, even in the form of microorganisms or organic compounds, have been found on the Moon.
The light areas of the Moon - the "continents" and the darker ones - the "seas" differ not only in appearance, but also in relief, geological history and the chemical composition of the substance covering them. On the younger surface of the "seas", covered with solidified lava, there are fewer craters than on the older surface of the "continents". In various parts of the Moon, such relief forms as cracks are noticeable, along which the crust is shifted vertically and horizontally. In this case, only fault-type mountains are formed, and there are no folded mountains, so typical for our planet, on the Moon.
The absence of erosion and weathering processes on the Moon allows us to consider it a kind of geological reserve, where for millions and billions of years all the landforms that have arisen during this time have been preserved. Thus, the study of the Moon makes it possible to understand the geological processes that took place on Earth in the distant past, of which no traces remain on our planet.
3. Earth.
Earth is the third planet from the Sun in the solar system. It revolves around the star at an average distance of 149.6 million km over a period of 365.24 days.
The Earth has a satellite - the Moon, which revolves around the Sun at an average distance of 384,400 km. The inclination of the earth's axis to the plane of the ecliptic is 66033`22``. The period of rotation of the planet around its axis is 23 hours 56 minutes 4.1 seconds. Rotation around its axis causes the change of day and night, and the tilt of the axis and circulation around the Sun - the change of seasons. The shape of the Earth is a geoid, approximately a triaxial ellipsoid, a spheroid. The average radius of the Earth is 6371.032 km, equatorial - 6378.16 km, polar - 6356.777 km. The surface area of the globe is 510 million km², the volume is 1.083 * 1012 km², the average density is 5518 kg / m³. The mass of the Earth is 5976 * 1021 kg.
The earth has magnetic and electric fields. The gravitational field of the Earth determines its spherical shape and the existence of the atmosphere. According to modern cosmogonic concepts, the Earth was formed about 4.7 billion years ago from the gaseous matter scattered in the protosolar system. As a result of the differentiation of matter, the Earth, under the influence of its gravitational field, under the conditions of heating of the earth's interior, arose and developed different in chemical composition, state of aggregation and physical properties of the shell - the geosphere: core (in the center), mantle, earth's crust, hydrosphere, atmosphere, magnetosphere. The composition of the Earth is dominated by iron (34.6%), oxygen (29.5%), silicon (15.2%), magnesium (12.7%). The earth's crust, mantle and inner part of the core are solid (the outer part of the core is considered liquid). From the surface of the Earth to the center, pressure, density and temperature increase.
The pressure in the center of the planet is 3.6 * 1011 Pa, the density is about 12.5 * 103 kg / m³, the temperature ranges from 50000ºС to 60000ºС.
The main types of the earth's crust are continental and oceanic; in the transition zone from the mainland to the ocean, an intermediate crust is developed.
Most of the Earth is occupied by the World Ocean (361.1 million km²; 70.8%), the land is 149.1 million km² (29.2%), and forms six continents and islands. It rises above the world ocean level by an average of 875 m (the highest height is 8848 m - Mount Chomolungma), mountains occupy more than 1/3 of the land surface. Deserts cover about 20% of the land surface, forests - about 30%, glaciers - over 10%. The average depth of the world ocean is about 3800 m (the greatest depth is 11020 m - the Mariana Trench (trough) in the Pacific Ocean). The volume of water on the planet is 1370 million km³, the average salinity is 35 g/l. The atmosphere of the Earth, the total mass of which is 5.15 * 1015 tons, consists of air - a mixture of mainly nitrogen (78.08%) and oxygen (20.95%), the rest is water vapor, carbon dioxide, as well as inert and other gases. The maximum land surface temperature is 570º-580º C (in the tropical deserts of Africa and North America), the minimum is about -900º C (in the central regions of Antarctica). The formation of the Earth and the initial stage of its development belong to pregeological history. The absolute age of the most ancient rocks is over 3.5 billion years. The geological history of the Earth is divided into two unequal stages: the Precambrian, which occupies approximately 5/6 of the entire geological chronology (about 3 billion years) and the Phanerozoic, covering the last 570 million years.
About 3-3.5 billion years ago, as a result of the natural evolution of matter, life arose on Earth, and the development of the biosphere began. The totality of all living organisms inhabiting it, the so-called living matter of the Earth, had a significant impact on the development of the atmosphere, hydrosphere and sedimentary shell. A new factor that has a powerful influence on the biosphere is the production activity of man, who appeared on Earth less than 3 million years ago. The high growth rate of the Earth's population (275 million people in 1000, 1.6 billion people in 1900 and approximately 6.3 billion people in 1995) and the increasing influence of human society on the natural environment have put forward the problems of the rational use of all natural resources and nature protection.
4. Ancient and modern studies of the Earth.
For the first time, the ancient Greek mathematician and astronomer Eratosthenes managed to obtain fairly accurate dimensions of our planet in the 1st century BC (an accuracy of about 1.3%). Eratosthenes discovered that at noon on the longest day of summer, when the Sun is at its highest in the sky of Aswan and its rays fall vertically, in Alexandria at the same time the Sun's zenith distance is 1/50 of a circle. Knowing the distance from Aswan to Alexandria, he was able to calculate the radius of the Earth, which, according to his calculations, was 6290 km. An equally significant contribution to astronomy was made by the Muslim astronomer and mathematician Biruni, who lived in the 10th-11th century AD. e. Despite the fact that he used the geocentric system, he was able to quite accurately determine the size of the Earth and the inclination of the equator to the ecliptic. The sizes of the planets, although they were determined by him, but with a big error; the only size he determined relatively accurately is the size of the moon.
In the 15th century, Copernicus put forward the heliocentric theory of the structure of the world. The theory, as is known, had no development for quite a long time, as it was persecuted by the church. The system was finally refined by I. Kepler at the end of the 16th century. Kepler also discovered the laws of planetary motion and calculated the eccentricities of their orbits, theoretically created a model of a telescope. Galileo, who lived somewhat later than Kepler, constructed a telescope with a magnification of 34.6 times, which allowed him to estimate even the height of the mountains on the moon. He also discovered a characteristic difference when observing stars and planets through a telescope: the clarity of the appearance and shape of the planets was much greater, and he also discovered several new stars. For almost 2000 years, astronomers believed that the distance from the Earth to the Sun is equal to 1200 Earth distances, i.e. making a mistake about 20 times! For the first time, these data were specified only at the end of the 17th century as 140 million km, i.e. with an error of 6.3% by the astronomers Cassini and Richet. They also determined the speed of light as 215 km / s, which was a significant breakthrough in astronomy, since they previously believed that the speed of light was infinite. Around the same time, Newton discovered the law of universal gravitation, and the decomposition of light into a spectrum, which marked the beginning of spectral analysis several centuries later.
The Earth seems to us so huge, so reliable and means so much to us that we do not notice her secondary position in the family of planets. The only weak consolation is that the Earth is the largest of the terrestrial planets. In addition, it has an atmosphere of medium power, a significant part of the earth's surface is covered with a thin heterogeneous layer of water. And around it revolves a majestic satellite, the diameter of which is equal to a quarter of the earth's diameter. However, these arguments are hardly sufficient to support our cosmic conceit. Tiny in astronomical terms, the Earth is our home planet and therefore deserves the most careful study. After the painstaking and hard work of dozens of generations of scientists, it was irrefutably proven that the Earth is not at all the “center of the universe”, but the most ordinary planet, i.e. cold ball moving around the sun. According to Kepler's laws, the Earth revolves around the Sun at a variable speed in a slightly elongated ellipse. It is closest to the sun in early January, when winter reigns in the Northern Hemisphere, and farthest away in early July, when we have summer. The difference in the distance of the Earth from the Sun between January and July is about 5 million km. Therefore, winters in the northern hemisphere are slightly warmer than in the southern, and summers, on the contrary, are slightly cooler. This is most clearly felt in the Arctic and Antarctica. The ellipticity of the Earth's orbit has only an indirect and very insignificant influence on the nature of the seasons. The reason for the change of seasons lies in the tilt of the earth's axis. The axis of rotation of the Earth is located at an angle of 66.5º to the plane of its movement around the Sun. For most practical problems, it can be assumed that the Earth's axis of rotation always moves in space parallel to itself. In fact, the axis of rotation of the Earth describes a small circle on the celestial sphere, making one complete revolution in 26 thousand years. In the next hundreds of years, the north pole of the world will be located not far from the Polar Star, then it will begin to move away from it, and the name of the last star in the handle of the Ursa Minor bucket - Polaris - will lose its meaning. In 12 thousand years, the celestial pole will approach the brightest star in the northern sky - Vega from the constellation Lyra. The described phenomenon is called the precession of the Earth's axis of rotation. The phenomenon of precession was already discovered by Hipparchus, who compared the positions of the stars in the catalog with the star catalog of Aristillus and Timocharis compiled long before him. Comparison of catalogs indicated to Hipparchus the slow movement of the axis of the world.
There are three outer shells of the Earth: the lithosphere, hydrosphere and atmosphere. The lithosphere is understood as the upper solid cover of the planet, which serves as the bed of the ocean, and on the continents coincides with the land. The hydrosphere is groundwater, the waters of rivers, lakes, seas and, finally, the oceans. Water covers 71% of the entire surface of the Earth. The average depth of the World Ocean is 3900 m.
5. Exploring the Earth from space
Man first appreciated the role of satellites in monitoring the state of agricultural land, forests and other natural resources of the Earth only a few years after the onset of the space age. The beginning was laid in 1960, when with the help of meteorological satellites "Tiros" map-like outlines of the globe were obtained, lying under the clouds. These first black-and-white TV images gave very little insight into human activity, and yet it was a first step. Soon new technical means were developed that made it possible to improve the quality of observations. Information was extracted from multispectral images in the visible and infrared (IR) regions of the spectrum. The first satellites designed to make the most of these opportunities were the Landsat. For example, the Landsat-D satellite, the fourth in a series, observed the Earth from an altitude of more than 640 km using advanced sensitive instruments, which allowed consumers to receive much more detailed and timely information. One of the first areas of application of images of the earth's surface was cartography. In the pre-satellite era, maps of many areas, even in the developed regions of the world, were inaccurate. The Landsat images have corrected and updated some of the existing maps of the United States. In the mid-1970s, NASA and the US Department of Agriculture decided to demonstrate the capabilities of the satellite system in forecasting the most important agricultural crop, wheat. Satellite observations, which turned out to be extremely accurate, were later extended to other agricultural crops. The use of satellite information has revealed its undeniable advantages in assessing the volume of timber in the vast territories of any country. It became possible to manage the process of deforestation and, if necessary, to give recommendations on changing the contours of the deforestation area from the point of view of the best preservation of the forest. Satellite images also made it possible to quickly assess the boundaries of forest fires, especially the “crown-shaped” ones that are characteristic of the western regions of North America, as well as the regions of Primorye and southern regions of Eastern Siberia in Russia.
Of great importance for humanity as a whole is the ability to observe almost continuously over the expanses of the World Ocean. It is above the depths of ocean water that monstrous forces are born of hurricanes and typhoons, bringing numerous victims and destruction to the inhabitants of the coast. Early warning to the public is often critical to saving the lives of tens of thousands of people. Determining the stocks of fish and other seafood is also of great practical importance. Ocean currents often curve, change course and size. For example, El Nino, a warm current in a southerly direction off the coast of Ecuador in some years can spread along the coast of Peru up to 12º S. When this happens, plankton and fish die in huge numbers, causing irreparable damage to the fisheries of many countries, including Russia. Large concentrations of unicellular marine organisms increase the mortality of fish, possibly due to the toxins they contain. Satellite observation helps to identify the “whims” of such currents and provide useful information to those who need it. According to some estimates by Russian and American scientists, the fuel savings, combined with the "extra catch" due to the use of information from satellites obtained in the infrared range, yields an annual profit of $ 2.44 million. The use of satellites for survey purposes has facilitated the task of plotting the course of ships .
6. The emergence of life on Earth
The emergence of living matter on Earth was preceded by a rather long and complex evolution of the chemical composition of the atmosphere, which ultimately led to the formation of a number of organic molecules. These molecules later served as a kind of “bricks” for the formation of living matter. According to modern data, the planets are formed from a primary gas-dust cloud, the chemical composition of which is similar to the chemical composition of the Sun and stars, their initial atmosphere consisted mainly of the simplest compounds of hydrogen - the most common element in space. Most of all there were molecules of hydrogen, ammonia, water and methane. In addition, the primary atmosphere should have been rich in inert gases - primarily helium and neon. At present, there are few noble gases on Earth, since they once dissipated (evaporated) into interplanetary space, like many hydrogen-containing compounds. However, a decisive role in establishing the composition of the earth's atmosphere was played by plant photosynthesis, in which oxygen is released. It is possible that a certain, and perhaps even significant, amount of organic matter was brought to Earth during the fall of meteorites and, possibly, even comets. Some meteorites are quite rich in organic compounds. It is estimated that over 2 billion years meteorites could bring to Earth from 108 to 1012 tons of such substances. Also, organic compounds can occur in small quantities as a result of volcanic activity, meteorite impacts, lightning, due to the radioactive decay of some elements. There are fairly reliable geological data indicating that already 3.5 billion years ago the Earth's atmosphere was rich in oxygen. On the other hand, the age of the earth's crust is estimated by geologists at 4.5 billion years. Life must have originated on Earth before the atmosphere became rich in oxygen, since the latter is mainly a product of the vital activity of plants. According to a recent estimate by the American specialist in planetary astronomy Sagan, life on Earth arose 4.0-4.4 billion years ago. The mechanism of the complication of the structure of organic substances and the appearance in them of the properties inherent in living matter has not yet been sufficiently studied. But it is already clear that such processes last for billions of years.
Any complex combination of amino acids and other organic compounds is not yet a living organism. It can, of course, be assumed that under some exceptional circumstances, somewhere on Earth, a certain “praDNA” arose, which served as the beginning of all living things. This is hardly the case if the hypothetical “praDNA” was similar to the modern one. The fact is that modern DNA itself is completely helpless. It can function only in the presence of enzyme proteins. To think that purely by chance, by “shaking up” individual proteins - polyatomic molecules, such a complex machine as “praDNA” and the complex of protein-enzymes necessary for its functioning could arise - this means believing in miracles. However, it can be assumed that DNA and RNA molecules originated from a more primitive molecule. For the first primitive living organisms formed on the planet, high doses of radiation can be a mortal danger, since mutations will occur so quickly that natural selection will not keep up with them.
The following question deserves attention: why does life on Earth not arise from non-living matter in our time? This can only be explained by the fact that the previously arisen life will not give an opportunity for a new birth of life. Microorganisms and viruses will literally eat the first sprouts of new life. We cannot completely exclude the possibility that life on Earth arose by chance. There is another circumstance that may be worth paying attention to. It is well known that all “living” proteins consist of 22 amino acids, while more than 100 amino acids are known in total. It is not entirely clear how these acids differ from their other “brothers”. Is there some deep connection between the origin of life and this amazing phenomenon? If life on Earth arose by chance, then life in the Universe is a rare phenomenon. For a given planet (like, for example, our Earth), the emergence of a special form of highly organized matter, which we call "life", is an accident. But in the vast expanses of the universe, life arising in this way should be a natural phenomenon. It should be noted once again that the central problem of the emergence of life on Earth - the explanation of the qualitative leap from "non-living" to "living" - is still far from clear. No wonder one of the founders of modern molecular biology, Professor Crick, at the Byurakan Symposium on the Problem of Extraterrestrial Civilizations in September 1971, said: “We do not see a path from the primordial soup to natural selection. It can be concluded that the origin of life is a miracle, but this only testifies to our ignorance.”
8. The only satellite of the Earth is the Moon.
Long gone are the days when people believed that the mysterious forces of the moon had an impact on their daily lives. But the Moon does have a variety of influences on the Earth, which are due to the simple laws of physics and, above all, dynamics. The most amazing feature of the motion of the Moon is that the speed of its rotation around its axis coincides with the average angular velocity of revolution around the Earth. Therefore, the Moon always faces the Earth with the same hemisphere. Since the Moon is the nearest celestial body, its distance from the Earth is known with the greatest accuracy, up to several centimeters from measurements using lasers and laser rangefinders. The smallest distance between the centers of the Earth and the Moon is 356,410 km. The greatest distance of the Moon from the Earth reaches 406,700 km, and the average distance is 384,401 km. The Earth's atmosphere bends the rays of light to such an extent that the entire Moon (or the Sun) can be seen even before sunrise or after sunset. The fact is that the refraction of light rays entering the atmosphere from airless space is about 0,
5º, i.e. equal to the apparent angular diameter of the moon.
Thus, when the upper edge of the true Moon is just below the horizon, the entire Moon is visible above the horizon. Another surprising result was obtained from tidal experiments. It turns out that the Earth is an elastic ball. Prior to these experiments, it was commonly believed that the Earth was viscous, like molasses or molten glass; with slight distortions, it would probably have to keep them or slowly return to its original form under the action of weak restoring forces. Experiments have shown that the Earth as a whole is given tidal forces and immediately returns to its original form after the cessation of their action. Thus, the Earth is not only harder than steel, but also more resilient.
Conclusion
We got acquainted with the current state of our planet. The future of our planet, and indeed the entire planetary system, if nothing unforeseen happens, seems clear. The probability that the established order of the planets will be disturbed by some wandering star is small, even within a few billion years.
In the near future, one should not expect strong changes in the flow of solar energy. It is likely that ice ages will repeat. A person is able to change the climate, but in doing so, he can make a mistake. The continents will rise and fall in subsequent epochs, but we hope that the processes will be slow. Massive meteorite impacts are possible from time to time. But basically, the planet Earth will retain its modern appearance.
Our planet is a huge ellipsoid consisting of rocks, metals and covered with water and soil. The Earth is one of the nine planets that revolve around the Sun; ranks fifth in terms of the size of the planets. The sun, together with the planets revolving around it, forms. Our galaxy, the Milky Way, has a diameter of about 100,000 light-years (that's how long it takes for light to travel to the last point of a given space).
The planets of the solar system describe ellipses around the sun, while also rotating around their own axes. The four planets closest to the Sun (Mercury, Venus, Earth, Mars) are called internal, the rest (Jupiter, Uranus, Neptune, Pluto) are external. Recently, scientists have found many planets in the solar system that are equal to or slightly smaller than Pluto in size, so in astronomy today there are only eight planets that make up the solar system, but we will stick to the standard theory.
The Earth moves in its orbit around the Sun at a speed of 107,200 km/h (29.8 km/s). In addition, it rotates around its axis of an imaginary rod passing through the northernmost and southernmost points of the Earth. The earth's axis is inclined to the plane of the ecliptic at an angle of 66.5°. Scientists calculated that if the Earth stopped, it would instantly burn out from the energy of its own speed. The ends of the axis are called the North and South Poles.
The Earth describes its path around the Sun in one year (365.25 days). Every fourth year contains 366 days (an extra day accumulates over 4 years), it is called a leap year. Due to the fact that the earth's axis has a tilt, the northern hemisphere is most tilted towards the Sun in June, and the southern - in December. In the hemisphere that is currently most inclined towards the Sun, it is summer. This means that in the other hemisphere it is winter and it is now the least illuminated by the sun's rays.
The imaginary lines running north and south of the equator, called the Tropic of Cancer and the Tropic of Capricorn, show where the sun's rays fall vertically on the surface of the Earth at noon. In the northern hemisphere this happens in June (the Tropic of Cancer) and in the southern hemisphere in December (the Tropic of Capricorn).
The solar system consists of nine planets orbiting the Sun, their satellites, many minor planets, comets and interplanetary dust.
Earth Movement
The Earth performs 11 different movements, but of these, the daily movement around the axis and the annual revolution around the Sun have important geographical significance.
In this case, the following definitions are introduced: aphelion is the most distant point in the orbit from the Sun (152 million km). Earth passes over it on July 5th. Perihelion is the closest point in orbit from the Sun (147 million km). The earth passes over it on January 3rd. The total length of the orbit is 940 million km.
The movement of the Earth around its axis goes from west to east, a complete revolution takes 23 hours 56 minutes 4 seconds. This time is taken as a day. The daily movement has 4 consequences:
- Compression at the poles and the spherical shape of the Earth;
- Change of day and night, seasons;
- The Coriolis force (named after the French scientist G. Coriolis) is the deviation of horizontally moving bodies in the Northern Hemisphere to the left, in the Southern Hemisphere to the right, this affects the direction of movement of air masses, sea currents, etc.;
- tidal phenomena.
The Earth's orbit has several important points corresponding to the days of the equinoxes and solstices. June 22 - the day of the summer solstice, when in the Northern Hemisphere - the longest, and in the Southern
- the shortest day of the year. On the Arctic Circle and inside it on this day - the polar day, on the South Arctic Circle and inside it - the polar night. December 22 is the winter solstice, the shortest day of the year in the northern hemisphere and the longest day in the southern hemisphere. Within the Arctic Circle - the polar night. South Arctic Circle - polar day. March 21 and September 23 are the days of the spring and autumn equinoxes, since the rays of the Sun fall vertically on the equator, on the whole Earth (except for the poles) the day is equal to the night.
Tropics - parallels with latitudes of 23.5 °, in which the Sun is at its zenith only once a year. Between the Northern and Southern tropics, the Sun is at its zenith twice a year, and outside them, the Sun is never at its zenith.
The Arctic Circles (Northern and Southern) are parallels in the Northern and Southern hemispheres with latitudes of 66.5 °, on which the polar day and night last exactly a day.
The polar day and night reach their maximum duration (six months) at the poles.
Time Zones. In order to regulate the differences in time resulting from the rotation of the Earth around its axis, the globe is conventionally divided into 24 time zones. Without them, no one could answer the question: "What time is it in other parts of the world?". The boundaries of these belts approximately coincide with the lines of longitude. In each time zone, people set their clocks to their own local time, depending on the point on Earth. The gap between the belts is 15°. In 1884, Greenwich Mean Time was introduced, which is calculated from the meridian passing through the Greenwich Observatory and having a longitude of 0 °.
The 180° East and West longitude lines coincide. This common line is called the International Date Line. Time at points on the Earth located west of this line is 12 hours ahead of time at points east of this line (symmetrical with respect to the date line). The time in these neighboring zones coincides, but traveling east you find yourself in yesterday, traveling west you find yourself in tomorrow.
Earth parameters
- Equatorial radius - 6378 km
- Polar radius - 6357 km
- Compression of the earth ellipsoid - 1: 298
- Average radius - 6371 km
- Equator circumference - 40,076 km
- Meridian length - 40,008 km
- Surface - 510 million km2
- Volume - 1.083 trillion. km3
- Weight - 5.98 10 ^ 24 kg
- Free fall acceleration - 9.81 m/s^2 (Paris) Distance from the Earth to the Moon - 384,000 km Distance from the Earth to the Sun - 150 million km.
Solar system
| Planet | The duration of one revolution around the sun | Period of revolution around its axis (days) | Average orbital speed (km/s) | Orbit deviation, deg (from the plane of the Earth's surface) | Gravity (Earth value = 1) |
| Mercury | 88 days | 58,65 | 48 | 7 | 0,38 |
| Venus | 224.7 days | 243 | 34,9 | 3,4 | 0.9 |
| Earth | 365.25 days | 0,9973 | 29,8 | 0 | 1 |
| Mars | 687 days | 1,02-60 | 24 | 1,8 | 0.38 |
| Jupiter | 11.86 years old | 0,410 | 12.9 | 1,3 | 2,53 |
| Saturn | 29.46 years old | 0,427 | 9,7 | 2,5 | 1,07 |
| Uranus | 84.01 years | 0,45 | 6,8 | 0,8 | 0,92 |
| Neptune | 164.8 years | 0,67 | 5,3 | 1,8 | 1,19 |
| Pluto | 247.7 years | 6,3867 | 4,7 | 17,2 | 0.05 |
| Planet | Diameter, in km | Distance from the Sun, in million km | Number of moons | Equator diameter (km) | Mass (Earth = 1) | Density (water = 1) | Volume (Earth = 1) |
| Mercury | 4878 | 58 | 0 | 4880 | 0,055 | 5,43 | 0,06 |
| Venus | 12103 | 108 | 0 | 12104 | 0,814 | 5,24 | 0,86 |
| Earth | 12756 | 150 | 1 | 12756 | 1 | 5,52 | 1 |
| Mars | 6794 | 228 | 2 | 6794 | 0,107 | 3,93 | 0,15 |
| Jupiter | 143800 | 778 | 16 | 142984 | 317,8 | 1,33 | 1323 |
| Saturn | 120 OOO | 1429 | 17 | 120536 | 95,16 | 0,71 | 752 |
| Uranus | 52400 | 2875 | 15 | 51118 | 14,55 | 1,31 | 64 |
| Neptune | 49400 | 4504 | 8 | 49532 | 17,23 | 1,77 | 54 |
| Pluto | 1100 | 5913 | 1 | 2320 | 0,0026 | 1,1 | 0,01 |
