Planets of the Solar System: eight and one. Internal structure of the Earth

Characteristics of the planet:

Distance from the Sun: 149.6 million km
Planet Diameter: 12,765 km
Days on the planet: 23h 56min 4s*
Year on the planet: 365 days 6h 9m 10s*
t° on the surface: global average +12°C (In Antarctica up to -85°C; in the Sahara Desert up to +70°C)
Atmosphere: 77% Nitrogen; 21% oxygen; 1% water vapor and other gases
Satellites: Moon

* period of rotation around its own axis (in Earth days)
**period of orbit around the Sun (in Earth days)

From the very beginning of the development of civilization, people were interested in the origin of the Sun, planets and stars. But the planet that is our common home, the Earth, is of most interest. Ideas about it have changed along with the development of science; the very concept of stars and planets, as we understand it now, was formed only a few centuries ago, which is negligible compared to the very age of the Earth.

Presentation: Planet Earth

The third planet from the Sun, which has become our home, has a satellite - the Moon, and is part of the group of terrestrial planets such as Mercury, Venus and Mars. The giant planets differ significantly from them in physical properties and structure. But even such a tiny planet in comparison with them, like the Earth, has an incredible mass in terms of comprehension - 5.97x1024 kilograms. It revolves around the star in an orbit at an average distance from the Sun of 149.0 million kilometers, rotating around its axis, which causes the change of days and nights. And the ecliptic of the orbit itself characterizes the seasons.

Our planet plays a unique role in the solar system, because Earth is the only planet that has life! The Earth was positioned in an extremely fortunate manner. It travels in orbit at a distance of almost 150,000,000 kilometers from the Sun, which means only one thing - It’s warm enough on Earth for water to remain in liquid form. Given hot temperatures, the water would simply evaporate, and in the cold it would turn into ice. Only on Earth is there an atmosphere in which humans and all living organisms can breathe.

The history of the origin of planet Earth

Starting from the Big Bang Theory and based on the study of radioactive elements and their isotopes, scientists have found out the approximate age of the earth's crust - it is about four and a half billion years, and the age of the Sun is about five billion years. Just like the entire galaxy, the Sun was formed as a result of the gravitational compression of a cloud of interstellar dust, and after the star, the planets included in the Solar System were formed.

As for the formation of the Earth itself as a planet, its very birth and formation lasted hundreds of millions of years and took place in several phases. During the birth phase, obeying the laws of gravity, a large number of planetesimals and large cosmic bodies fell onto its ever-growing surface, which later made up almost the entire modern mass of the earth. Under the influence of such bombardment, the planet's substance warmed up and then melted. Under the influence of gravity, heavy elements such as ferrum and nickel created the core, and lighter compounds formed the earth's mantle, crust with continents and oceans lying on its surface, and an atmosphere that was initially very different from the present one.

Internal structure of the Earth

Of the planets of its group, the Earth has the greatest mass and therefore has the greatest internal energy - gravitational and radiogenic, under the influence of which processes in the earth's crust still continue, as can be seen from volcanic and tectonic activity. Although igneous, metamorphic and sedimentary rocks have already formed, forming the outlines of landscapes that are gradually changing under the influence of erosion.

Beneath the atmosphere of our planet is a solid surface called the earth's crust. It is divided into huge pieces (slabs) of solid rock, which can move and, when moving, touch and push each other. As a result of such movement, mountains and other features of the earth's surface appear.

The earth's crust has a thickness of 10 to 50 kilometers. The crust “floats” on the liquid earth’s mantle, the mass of which is 67% of the mass of the entire Earth and extends to a depth of 2890 kilometers!

The mantle is followed by an outer liquid core, which extends into the depths for another 2260 kilometers. This layer is also mobile and capable of emitting electric currents, which create the planet’s magnetic field!

At the very center of the Earth is the inner core. It is very hard and contains a lot of iron.

Atmosphere and surface of the Earth

The Earth is the only one of all the planets in the solar system that has oceans - they cover more than seventy percent of its surface. Initially, water in the atmosphere in the form of steam played a big role in the formation of the planet - the greenhouse effect raised the temperature on the surface by those tens of degrees necessary for the existence of water in the liquid phase, and in combination with solar radiation gave rise to the photosynthesis of living matter - organic matter.

From space, the atmosphere appears as a blue border around the planet. This thin dome consists of 77% nitrogen, 20% oxygen. The rest is a mixture of various gases. Earth's atmosphere contains much more oxygen than any other planet. Oxygen is vital for animals and plants.

This unique phenomenon can be regarded as a miracle or considered an incredible coincidence of chance. It was the ocean that gave rise to the origin of life on the planet, and, as a consequence, the emergence of homo sapiens. Surprisingly, the oceans still hold many secrets. Developing, humanity continues to explore space. Entering low-Earth orbit has made it possible to gain a new understanding of many of the geoclimatic processes occurring on Earth, the mysteries of which are still to be further studied by more than one generation of people.

Earth's satellite - Moon

Planet Earth has its only satellite - the Moon. The first to describe the properties and characteristics of the Moon was the Italian astronomer Galileo Galilei, he described the mountains, craters and plains on the surface of the Moon, and in 1651 the astronomer Giovanni Riccioli wrote a map of the visible side of the lunar surface. In the 20th century, on February 3, 1966, the Luna-9 lander landed on the Moon for the first time, and a few years later, on July 21, 1969, a person set foot on the surface of the Moon for the first time.

The Moon always faces planet Earth with only one side. On this visible side of the Moon, flat “seas”, chains of mountains and multiple craters of various sizes are visible. The other side, invisible from Earth, has a large cluster of mountains and even more craters on the surface, and the light reflecting from the Moon, thanks to which at night we can see it in a pale lunar color, is weakly reflected rays from the Sun.

Planet Earth and its satellite the Moon are very different in many properties, while the ratio of stable oxygen isotopes of planet Earth and its satellite the Moon is the same. Radiometric studies have shown that the age of both celestial bodies is the same, approximately 4.5 billion years. These data suggest the origin of the Moon and the Earth from the same substance, which gives rise to several interesting hypotheses about the origin of the Moon: from the origin of the same protoplanetary cloud, the capture of the Moon by the Earth, and the formation of the Moon from a collision of the Earth with a large object.

Earth is the third planet in the solar system. Find out the description of the planet, mass, orbit, size, interesting facts, distance to the Sun, composition, life on Earth.

Of course we love our planet. And not only because this is our home, but also because this is a unique place in the solar system and the Universe, because so far we only know life on Earth. It lives in the inner part of the system and occupies a place between Venus and Mars.

Planet Earth also called the Blue Planet, Gaia, World and Terra, which reflects its role for each people in historical terms. We know that our planet is rich in many different forms of life, but how exactly did it manage to become so? First, consider interesting facts about the Earth.

Interesting facts about planet Earth

Rotation gradually slows down

For earthlings, the entire process of slowing down the rotation of the axis occurs almost imperceptibly - 17 milliseconds per 100 years. But the nature of the speed is not uniform. This results in an increase in the length of the day. After 140 million years, a day will cover 25 hours.

The earth was believed to be the center of the universe

Ancient scientists could observe celestial objects from the position of our planet, so it seemed that all objects in the sky were moving relative to us, and we remained at one point. As a result, Copernicus stated that the Sun (the heliocentric system of the world) is at the center of everything, although now we know that this does not correspond to reality, if we take the scale of the Universe.

Endowed with a powerful magnetic field

The Earth's magnetic field is created by the nickel-iron planetary core, which rotates rapidly. The field is important because it protects us from the influence of the solar wind.

Has one satellite

If you look at the percentage, the Moon is the largest satellite in the system. But in reality it is in 5th position in size.

The only planet not named after a deity

Ancient scientists named all 7 planets in honor of the gods, and modern scientists followed the tradition when discovering Uranus and Neptune.

First in density

Everything is based on the composition and specific part of the planet. So the core is represented by metal and bypasses the crust in density. The average density of the earth is 5.52 grams per cm 3.

Size, mass, orbit of planet Earth

With a radius of 6371 km and a mass of 5.97 x 10 24 kg, the Earth ranks 5th in size and massiveness. It is the largest terrestrial planet, but it is smaller in size than the gas and ice giants. However, in terms of density (5.514 g/cm3) it ranks first in the Solar System.

Polar compression	0,0033528
Equatorial	6378.1 km
Polar radius	6356.8 km
Average radius	6371.0 km
Great circle circumference	40,075.017 km (equator) (meridian)
Surface area	510,072,000 km²
Volume	10.8321 10 11 km³
Weight	5.9726 10 24 kg
Average density	5.5153 g/cm³
Acceleration free falls at the equator	9.780327 m/s²
First escape velocity	7.91 km/s
Second escape velocity	11.186 km/s
Equatorial speed rotation	1674.4 km/h
Rotation period	(23 h 56 m 4,100 s)
Axis tilt	23°26’21",4119
Albedo	0.306 (Bond) 0.367 (geom.)

There is a slight eccentricity in the orbit (0.0167). The distance from the star at perihelion is 0.983 AU, and at aphelion – 1.015 AU.

One passage around the Sun takes 365.24 days. We know that due to the existence of leap years, we add a day every 4 passes. We are used to thinking that a day lasts 24 hours, but in reality this time takes 23 hours 56 minutes and 4 seconds.

If you observe the rotation of the axis from the poles, you can see that it occurs counterclockwise. The axis is inclined at 23.439281° from the perpendicular to the orbital plane. This affects the amount of light and heat.

If the North Pole is turned towards the Sun, then summer occurs in the northern hemisphere, and winter in the southern hemisphere. At a certain time, the Sun does not rise at all over the Arctic Circle, and then night and winter last there for 6 months.

Composition and surface of planet Earth

The shape of planet Earth is like a spheroid, flattened at the poles and with a convexity at the equatorial line (diameter - 43 km). This is due to rotation.

The structure of the Earth is represented by layers, each of which has its own chemical composition. It differs from other planets in that our core has a clear distribution between the solid inner (radius - 1220 km) and the liquid outer (3400 km).

Next comes the mantle and crust. The first deepens to 2890 km (the densest layer). It is represented by silicate rocks with iron and magnesium. The crust is divided into lithosphere (tectonic plates) and asthenosphere (low viscosity). You can carefully examine the structure of the Earth in the diagram.

The lithosphere breaks down into solid tectonic plates. These are rigid blocks that move relative to each other. There are points of connection and break. It is their contact that leads to earthquakes, volcanic activity, the creation of mountains and ocean trenches.

There are 7 main plates: Pacific, North American, Eurasian, African, Antarctic, Indo-Australian and South American.

Our planet is notable for the fact that approximately 70.8% of its surface is covered with water. The bottom map of the Earth shows tectonic plates.

The earth's landscape is different everywhere. The submerged surface resembles mountains and has underwater volcanoes, oceanic trenches, canyons, plains and even oceanic plateaus.

During the development of the planet, the surface was constantly changing. Here it is worth considering the movement of tectonic plates, as well as erosion. It also affects the transformation of glaciers, the creation of coral reefs, meteorite impacts, etc.

Continental crust is represented by three varieties: magnesium rocks, sedimentary and metamorphic. The first is divided into granite, andesite and basalt. Sedimentary makes up 75% and is created by burying accumulated sediment. The latter is formed during the icing of sedimentary rock.

From the lowest point, the surface height reaches -418 m (at the Dead Sea) and rises to 8848 m (the top of Everest). The average height of the land above sea level is 840 m. The mass is also divided between the hemispheres and continents.

The outer layer contains soil. This is a certain line between the lithosphere, atmosphere, hydrosphere and biosphere. Approximately 40% of the surface is used for agricultural purposes.

Atmosphere and temperature of planet Earth

There are 5 layers of the earth's atmosphere: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The higher you rise, the less air, pressure and density you will feel.

The troposphere is located closest to the surface (0-12 km). Contains 80% of the mass of the atmosphere, with 50% located within the first 5.6 km. It consists of nitrogen (78%) and oxygen (21%) with admixtures of water vapor, carbon dioxide and other gaseous molecules.

In the interval of 12-50 km we see the stratosphere. It is separated from the first tropopause - a line with relatively warm air. This is where the ozone layer is located. The temperature rises as the layer absorbs ultraviolet light. The atmospheric layers of the Earth are shown in the figure.

This is a stable layer and is practically free from turbulence, clouds and other weather formations.

At an altitude of 50-80 km there is the mesosphere. This is the coldest place (-85°C). It is located near the mesopause, extending from 80 km to the thermopause (500-1000 km). The ionosphere lives within the range of 80-550 km. Here the temperature increases with altitude. In the photo of the Earth you can admire the northern lights.

The layer is devoid of clouds and water vapor. But it is here that auroras form and the International Space Station is located (320-380 km).

The outermost sphere is the exosphere. This is a transition layer to outer space, devoid of an atmosphere. Represented by hydrogen, helium and heavier molecules with low density. However, the atoms are so scattered that the layer does not behave like a gas, and particles are constantly being removed into space. Most of the satellites live here.

This mark is influenced by many factors. The Earth makes an axial revolution every 24 hours, which means one side always experiences night and lower temperatures. In addition, the axis is tilted, so the northern and southern hemispheres alternately move away and move closer.

All this creates seasonality. Not every part of the earth experiences sharp drops and rises in temperatures. For example, the amount of light entering the equatorial line remains virtually unchanged.

If we take the average, we get 14°C. But the maximum was 70.7°C (Lut Desert), and the minimum of -89.2°C was reached at the Soviet Vostok station on the Antarctic plateau in July 1983.

Moon and asteroids of the Earth

The planet has only one satellite, which affects not only the physical changes of the planet (for example, the ebb and flow of tides), but is also reflected in history and culture. To be precise, the Moon is the only celestial body on which a person has walked. This happened on July 20, 1969 and the right to take the first step went to Neil Armstrong. Overall, 13 astronauts landed on the satellite.

The Moon appeared 4.5 billion years ago due to the collision of the Earth and a Martian-sized object (Theia). We can be proud of our satellite, because it is one of the largest moons in the system, and also ranks second in density (after Io). It is in gravitational locking (one side always faces the Earth).

The diameter covers 3474.8 km (1/4 of the Earth), and the mass is 7.3477 x 10 22 kg. The average density is 3.3464 g/cm3. In terms of gravity it reaches only 17% of the Earth's. The moon influences the earth's tides, as well as the activity of all living organisms.

Don't forget that there are lunar and solar eclipses. The first happens when the Moon falls into the Earth's shadow, and the second happens when a satellite passes between us and the Sun. The satellite's atmosphere is weak, causing temperatures to fluctuate greatly (from -153°C to 107°C).

Helium, neon and argon can be found in the atmosphere. The first two are created by the solar wind, and argon is due to the radioactive decay of potassium. There is also evidence of frozen water in craters. The surface is divided into different types. There is Maria - flat plains that ancient astronomers mistook for seas. Terras are lands, like highlands. Even mountainous areas and craters can be seen.

The Earth has five asteroids. Satellite 2010 TK7 resides at L4, and asteroid 2006 RH120 approaches the Earth-Moon system every 20 years. If we talk about artificial satellites, there are 1265 of them, as well as 300,000 pieces of debris.

Formation and evolution of planet Earth

In the 18th century, humanity came to the conclusion that our terrestrial planet, like the entire solar system, emerged from a nebulous cloud. That is, 4.6 billion years ago, our system resembled a circumstellar disk, represented by gas, ice and dust. Then most of it approached the center and, under pressure, transformed into the Sun. The remaining particles created the planets we know.

The primordial Earth appeared 4.54 billion years ago. From the very beginning, it was molten due to volcanoes and frequent collisions with other objects. But 4-2.5 billion years ago, solid crust and tectonic plates appeared. Degassing and volcanoes created the first atmosphere, and ice arriving on comets formed the oceans.

The surface layer did not remain frozen, so the continents converged and moved apart. About 750 million years ago, the very first supercontinent began to break apart. Pannotia was created 600-540 million years ago, and the last one (Pangea) collapsed 180 million years ago.

The modern picture was created 40 million years ago and took hold 2.58 million years ago. The last ice age, which began 10,000 years ago, is currently underway.

It is believed that the first hints of life on Earth appeared 4 billion years ago (Archean eon). Due to chemical reactions, self-replicating molecules appeared. Photosynthesis created molecular oxygen, which, together with ultraviolet rays, formed the first ozone layer.

Then various multicellular organisms began to appear. Microbial life arose 3.7-3.48 billion years ago. 750-580 million years ago, most of the planet was covered with glaciers. Active reproduction of organisms began during the Cambrian explosion.

Since that time (535 million years ago), history includes 5 major extinction events. The last one (the death of dinosaurs from a meteorite) occurred 66 million years ago.

They were replaced by new species. The African ape-like animal stood on its hind legs and freed its forelimbs. This stimulated the brain to use different tools. Then we know about the development of agricultural crops, socialization and other mechanisms that led us to modern man.

Reasons for the habitability of planet Earth

If a planet meets a number of conditions, then it is considered potentially habitable. Now the Earth is the only lucky one with developed life forms. What is needed? Let's start with the main criterion - liquid water. In addition, the main star must provide enough light and heat to maintain the atmosphere. An important factor is location in the habitat zone (the distance of the Earth from the Sun).

We should understand how lucky we are. After all, Venus is similar in size, but due to its close location to the Sun, it is a hellishly hot place with acid rain. And Mars, which lives behind us, is too cold and has a weak atmosphere.

Planet Earth Research

The first attempts to explain the origin of the Earth were based on religion and myths. Often the planet became a deity, namely a mother. Therefore, in many cultures, the history of everything begins with the mother and the birth of our planet.

There are also a lot of interesting things in the form. In ancient times, the planet was considered flat, but different cultures added their own characteristics. For example, in Mesopotamia, a flat disk floated in the middle of the ocean. The Mayans had 4 jaguars that held up the heavens. For the Chinese it was generally a cube.

Already in the 6th century BC. e. scientists sewed it onto a round shape. Surprisingly, in the 3rd century BC. e. Eratosthenes even managed to calculate the circle with an error of 5-15%. The spherical shape became established with the advent of the Roman Empire. Aristotle spoke about changes in the earth's surface. He believed that it happens too slowly, so a person is not able to catch it. This is where attempts to understand the age of the planet arise.

Scientists are actively studying geology. The first catalog of minerals was created by Pliny the Elder in the 1st century AD. In 11th century Persia, explorers studied Indian geology. The theory of geomorphology was created by the Chinese naturalist Shen Guo. He identified marine fossils located far from the water.

In the 16th century, understanding and exploration of the Earth expanded. We should thank the heliocentric model of Copernicus, which proved that the Earth is not the universal center (previously they used the geocentric system). And also Galileo Galilei for his telescope.

In the 17th century, geology became firmly established among other sciences. They say that the term was coined by Ulysses Aldvandi or Mikkel Eschholt. The fossils discovered at that time caused serious controversy in the age of the earth. All the religious people insisted on 6000 years (as the Bible said).

This debate ended in 1785 when James Hutton declared that the Earth was much older. It was based on the erosion of rocks and the calculation of the time required for this. In the 18th century, scientists were divided into 2 camps. The former believed that the rocks were deposited by floods, while the latter complained about the fiery conditions. Hutton stood in firing position.

The first geological maps of the Earth appeared in the 19th century. The main work is “Principles of Geology”, published in 1830 by Charles Lyell. In the 20th century, age calculations became much easier thanks to radiometric dating (2 billion years). However, the study of tectonic plates has already led to the modern mark of 4.5 billion years.

The future of planet Earth

Our life depends on the behavior of the Sun. However, each star has its own evolutionary path. It is expected that in 3.5 billion years it will increase in volume by 40%. This will increase the flow of radiation, and the oceans may simply evaporate. Then the plants will die, and in a billion years all living things will disappear, and the constant average temperature will be fixed at around 70°C.

In 5 billion years, the Sun will transform into a red giant and shift our orbit by 1.7 AU.

If you look at the entire earth's history, then humanity is just a fleeting blip. However, the Earth remains the most important planet, home and unique place. One can only hope that we will have time to populate other planets outside our system before the critical period of solar development. Below you can explore a map of the Earth's surface. In addition, our website contains many beautiful high-resolution photos of the planet and places on Earth from space. Using online telescopes from the ISS and satellites, you can observe the planet for free in real time.

Click on the image to enlarge it

On March 13, 1781, English astronomer William Herschel discovered the seventh planet of the solar system - Uranus. And on March 13, 1930, American astronomer Clyde Tombaugh discovered the ninth planet of the solar system - Pluto. By the beginning of the 21st century, it was believed that the solar system included nine planets. However, in 2006, the International Astronomical Union decided to strip Pluto of this status.

There are already 60 known natural satellites of Saturn, most of which were discovered using spacecraft. Most of the satellites consist of rocks and ice. The largest satellite, Titan, discovered in 1655 by Christiaan Huygens, is larger than the planet Mercury. The diameter of Titan is about 5200 km. Titan orbits Saturn every 16 days. Titan is the only moon to have a very dense atmosphere, 1.5 times larger than Earth's, consisting primarily of 90% nitrogen, with moderate methane content.

The International Astronomical Union officially recognized Pluto as a planet in May 1930. At that moment, it was assumed that its mass was comparable to the mass of the Earth, but later it was found that Pluto’s mass is almost 500 times less than the Earth’s, even less than the mass of the Moon. Pluto's mass is 1.2 x 10.22 kg (0.22 Earth's mass). Pluto's average distance from the Sun is 39.44 AU. (5.9 to 10 to 12 degrees km), radius is about 1.65 thousand km. The period of revolution around the Sun is 248.6 years, the period of rotation around its axis is 6.4 days. Pluto's composition is believed to include rock and ice; the planet has a thin atmosphere consisting of nitrogen, methane and carbon monoxide. Pluto has three moons: Charon, Hydra and Nix.

At the end of the 20th and beginning of the 21st centuries, many objects were discovered in the outer solar system. It has become obvious that Pluto is only one of the largest Kuiper Belt objects known to date. Moreover, at least one of the belt objects - Eris - is a larger body than Pluto and is 27% heavier. In this regard, the idea arose to no longer consider Pluto as a planet. On August 24, 2006, at the XXVI General Assembly of the International Astronomical Union (IAU), it was decided to henceforth call Pluto not a “planet”, but a “dwarf planet”.

At the conference, a new definition of a planet was developed, according to which planets are considered bodies that revolve around a star (and are not themselves a star), have a hydrostatically equilibrium shape and have “cleared” the area in the area of their orbit from other, smaller objects. Dwarf planets will be considered objects that orbit a star, have a hydrostatically equilibrium shape, but have not “cleared” the nearby space and are not satellites. Planets and dwarf planets are two different classes of objects in the Solar System. All other objects orbiting the Sun that are not satellites will be called small bodies of the Solar System.

Thus, since 2006, there have been eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. The International Astronomical Union officially recognizes five dwarf planets: Ceres, Pluto, Haumea, Makemake, and Eris.

On June 11, 2008, the IAU announced the introduction of the concept of "plutoid". It was decided to call celestial bodies revolving around the Sun in an orbit whose radius is greater than the radius of Neptune’s orbit, whose mass is sufficient for gravitational forces to give them an almost spherical shape, and which do not clear the space around their orbit (that is, many small objects revolve around them) ).

Since it is still difficult to determine the shape and thus the relationship to the class of dwarf planets for such distant objects as plutoids, scientists recommended temporarily classifying all objects whose absolute asteroid magnitude (brilliance from a distance of one astronomical unit) is brighter than +1 as plutoids. If it later turns out that an object classified as a plutoid is not a dwarf planet, it will be deprived of this status, although the assigned name will be retained. The dwarf planets Pluto and Eris were classified as plutoids. In July 2008, Makemake was included in this category. On September 17, 2008, Haumea was added to the list.

The material was prepared based on information from open sources

The solar system is a planetary system that includes the central star - the Sun - and all the natural objects of space revolving around it. It was formed by gravitational compression of a gas and dust cloud approximately 4.57 billion years ago. We will find out which planets are part of the solar system, how they are located in relation to the Sun and their brief characteristics.

Brief information about the planets of the solar system

The number of planets in the Solar System is 8, and they are classified in order of distance from the Sun:

Inner planets or terrestrial planets- Mercury, Venus, Earth and Mars. They consist mainly of silicates and metals
Outer planets– Jupiter, Saturn, Uranus and Neptune are the so-called gas giants. They are much more massive than the terrestrial planets. The largest planets in the solar system, Jupiter and Saturn, consist mainly of hydrogen and helium; The smaller gas giants, Uranus and Neptune, contain methane and carbon monoxide in their atmospheres, in addition to hydrogen and helium.

Rice. 1. Planets of the Solar System.

The list of planets in the Solar System, in order from the Sun, looks like this: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. By listing the planets from largest to smallest, this order changes. The largest planet is Jupiter, followed by Saturn, Uranus, Neptune, Earth, Venus, Mars and finally Mercury.

All planets orbit the Sun in the same direction as the Sun's rotation (counterclockwise when viewed from the Sun's north pole).

Mercury has the highest angular velocity - it manages to complete a full revolution around the Sun in just 88 Earth days. And for the most distant planet - Neptune - the orbital period is 165 Earth years.

Most of the planets rotate around their axis in the same direction as they revolve around the Sun. The exceptions are Venus and Uranus, with Uranus rotating almost “lying on its side” (axis tilt is about 90 degrees).

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Table. The sequence of planets in the solar system and their features.

*Planet*	*Distance from the Sun*	*Circulation period*	*Rotation period*	*Diameter, km.*	*Number of satellites*	*Density g / cu. cm.*
Mercury

Terrestrial planets (inner planets)

The four planets closest to the Sun consist predominantly of heavy elements, have a small number of satellites, and have no rings. They are largely composed of refractory minerals such as silicates, which form their mantle and crust, and metals, such as iron and nickel, which form their core. Three of these planets—Venus, Earth, and Mars—have atmospheres.

Mercury- is the closest planet to the Sun and the smallest planet in the system. The planet has no satellites.
Venus- is close in size to the Earth and, like the Earth, has a thick silicate shell around an iron core and an atmosphere (because of this, Venus is often called the “sister” of the Earth). However, the amount of water on Venus is much less than on Earth, and its atmosphere is 90 times denser. Venus has no satellites.

Venus is the hottest planet in our system, its surface temperature exceeds 400 degrees Celsius. The most likely reason for such high temperatures is the greenhouse effect, which occurs due to a dense atmosphere rich in carbon dioxide.

Rice. 2. Venus is the hottest planet in the solar system

Earth- is the largest and most dense of the terrestrial planets. The question of whether life exists anywhere other than Earth remains open. Among the terrestrial planets, the Earth is unique (primarily due to its hydrosphere). The Earth's atmosphere is radically different from the atmospheres of other planets - it contains free oxygen. The Earth has one natural satellite - the Moon, the only large satellite of the terrestrial planets of the Solar System.
Mars smaller than Earth and Venus. It has an atmosphere consisting mainly of carbon dioxide. There are volcanoes on its surface, the largest of which, Olympus, exceeds the size of all terrestrial volcanoes, reaching a height of 21.2 km.

Outer Solar System

The outer region of the Solar System is home to gas giants and their satellites.

Jupiter- has a mass 318 times that of Earth, and 2.5 times more massive than all other planets combined. It consists mainly of hydrogen and helium. Jupiter has 67 moons.
Saturn- Known for its extensive ring system, it is the least dense planet in the solar system (its average density is less than that of water). Saturn has 62 satellites.

Rice. 3. Planet Saturn.

Uranus- the seventh planet from the Sun is the lightest of the giant planets. What makes it unique among other planets is that it rotates “lying on its side”: the inclination of its rotation axis to the ecliptic plane is approximately 98 degrees. Uranus has 27 moons.
Neptune- the last planet in the solar system. Although slightly smaller than Uranus, it is more massive and therefore denser. Neptune has 14 known moons.

What have we learned?

One of the interesting topics in astronomy is the structure of the solar system. We learned what names the planets of the solar system are, in what sequence they are located in relation to the Sun, what are their distinctive features and brief characteristics. This information is so interesting and educational that it will be useful even for 4th grade children.

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