Terrestrial planets with satellites. Earth group. Features of the terrestrial planets

There are four objects in the solar system that are commonly called planets. terrestrial group: Mercury (smallest), Venus and Mars, and Earth (largest). They are also called internal, solid-state, in contrast to the outer gas giant planets.

General characteristics

Facts about the terrestrial planets mainly concern their objective, visual characteristics, due to the fact that the physical presence of a person is still possible only on one of these space objects - Earth.

It is known that these have significant density, consist of iron and silicates, as well as oxygen, silicon, magnesium, and aluminum. The facts we know about the terrestrial planets say that all these objects have a certain structure. In the center is a core containing iron and nickel. Then there is the mantle, which includes silicates. It is covered by a crust, also consisting of silicate rocks, but enriched with other elements. Mercury has no crust, which was, as scientists suggest, the result of meteorite bombardment of a space object. Earth and Mars have satellites. Mercury and Venus do not have them.

Earth-like

Most scientists believe that the most good conditions For the emergence of biological life, they exist precisely on the planets of this group. That is why the search and comprehensive study of these space objects attracts increased attention from scientists from all countries. Example of planets earth type serve as so-called super-Earths. As of 2012, more than fifty of them were discovered. On each of them, according to scientists, the emergence of life is theoretically possible.

Facts about the terrestrial planets

But let's return to the solar system. Motherland- the third in a row from the Sun. It is the largest of the solid planets in terms of density, diameter and mass. Let's learn a few facts about our planet:

• Today this is the only known to man cosmic bodies, on which biological life has been discovered.
• The earth was formed a long time ago - over four and a half billion solar years ago. And life on our planet appeared, according to most scientists, about half a billion years after that.
• In conjunction with magnetic field ozone layer weakens harmful solar radiation. This is one of the conditions for the possibility of life on the planet.
• The Earth's crust is made up of tectonic plates moving at a speed of several centimeters per year!
• More than 70 percent of the planet's surface is occupied by water. Sushi accounts for less than 30 percent. Water is vital for all known living forms.
• The planet's poles are covered by Arctic ice and an Antarctic ice sheet.
• According to some scientists, living conditions biological organisms The earth can survive for quite a long time: more than two billion years. Unless, of course, you try to artificially violate these conditions (as a result of the harmful and thoughtless activities of man and his impact on the biosphere).
• Our planet revolves around the Sun in approximately 365.26 days, which is a sidereal year.
• The Moon, the Earth's satellite, causes the tide and also stabilizes earth's axis, gradually slowing down the rotation of our planet.
• repeatedly caused extinction various types organisms, leading to significant changes in the biosphere. These and other facts about the terrestrial planets became known thanks to the activities of scientists who are constantly studying the processes occurring in the solar system.

Mars

Venus

This celestial body also belongs to a class called “terrestrial planets.” Interesting facts about studies of its composition and surface attract the attention of many scientists at all times. Let's consider the main ones:

• Venus is the brightest of the planets. On a clear moonless night, it is capable of casting a shadow on the earth's surface.
• Venus has no satellites, like Mercury. Its sphere is almost ideal, unlike the earthly, flattened one.
• It is impossible to see the Sun due to constant clouds. There is also no change of seasons as such.
• Scientists suggest that Venus previously contained large reserves of water, but it evaporated long ago as a result of increased solar radiation.
• Life on Venus is impossible due to the very high temperature.
• A day on the planet lasts slightly less than an Earth year!

Mercury

Let's look at 2-3 more interesting facts about the terrestrial planets.

• Mercury is the smallest (as of 2006, when Pluto lost its planetary status) and closest planet to our main luminary in the Solar System.

• This body is the least studied. Thus, it was only in 2009 that scientists compiled complete maps of the surface of this celestial body.
• A day on the planet is twice as long as a year!

Here are 2-3 more interesting facts about the terrestrial planets:

• Deimos, the moon of Mars, rises and sets twice a day.
• When Mars comes close to Earth, they record greatest number UFO sightings.

This is how we can describe the terrestrial planets. All the facts about space provided by scientists have recently aroused great interest among the general public. This is connected both with the possibility of the emergence of biological life on other planets and with the ever-increasing ability of mankind to comprehend the secrets of the universe.

Information project

"Terrestrial Planets"

Completed:

11th grade students

Boykova Kristina

Rumyantseva Natalya

MBOU "Maksatikha Secondary School No. 2"

Head: Krasilnikova O.A.

2014-2015 academic year

Formulation of the problem.

Goals and objectives of the project.

Theoretical material. (Presentation)

1. Terrestrial planets.

   Main characteristics.

   Mercury.

   Venus.

   Mars.

   Earth.

Conclusion.

Problem

IN school course In grade 11 we consider basic questions in astronomy. These questions interested us very much, and we decided to make a project related to this topic. Planet Earth - the only planet, on which life has been discovered. We were interested in the terrestrial planets, including Earth, Mars, Venus and Mercury. So what are these planets? Now we will tell you about it!

Project goals and objectives

Develop knowledge about the terrestrial planets.

Introduce students to facts about the terrestrial planets.

Terrestrial planets.

Terrestrial planets - four planets of the solar system: Mercury, Venus, Earth and Mars. They are also calledinner planets , in contrast to the outer planets - giant planets. In structure and composition, some rocky asteroids, for example Vesta, are close to the terrestrial planets.

Main characteristics.

Terrestrial planets are highly dense and consist predominantly of silicates and metallic iron. The largest terrestrial planet, Earth, is more than 14 times less massive than the least massive gas planet, Uranus, but is approximately 400 times more massive than the largest known Kuiper Belt object.

Terrestrial planets consist mainly of oxygen, silicon, iron, magnesium, aluminum and other heavy elements.

All terrestrial planets have the following structure:

• In the center is a core of iron mixed with nickel.

  The mantle consists of silicates.

  Crust formed as a result of partial melting of the mantle and also consisting of silicate rocks, but enriched in incompatible elements. Of the terrestrial planets, Mercury does not have a crust, which is explained by its destruction as a result of meteorite bombardment. Earth is different from other terrestrial planets high degree chemical differentiation of matter and the wide distribution of granites in the crust.

  Two of the terrestrial planets (the farthest from the Sun - Earth and Mars) have satellites. None of them have rings.

Mercury.

The mass of the planet is 3.3 10 23 kg. AveragedensityMercury is quite large - 5.43 g/cm³. Acceleration of gravityon Mercury it is 3.70 m/s².Second escape velocity - 4,25 km/s Despite its smaller radius, Mercury still exceeds such satellites in massgiant planets like GanymedeAndTitanium. Astronomical symbolMercury is a stylized image of the winged helmet of the god Mercury with hiscaduceus.Mercury moves around the Sun along a fairly elongatedelliptical orbit ( eccentricity 0.205) at an average distance of 57.91 million km (0.387 AU).According to their own physical characteristics Mercury remindsMoon. It has no natural satellites, but has a very rarefied atmosphere. The planet has a large iron core, which is the sourcemagnetic field, the strength of which is 0.01 of the earth's. Mercury's core makes up 83% of the planet's total volume. Temperatures on the surface of Mercury range from 90 to 700TO(from −180 to +430 °C). Sunny side warms up much more than the polar regions and back side planets. The surface of Mercury also resembles in many wayslunar - she is strongcratered. The density of craters varies across different areas. The largest crater on Mercury is named after the great Dutch painterRembrandt, its diameter is 716 km. However, the similarity is incomplete - formations are visible on Mercury that are not found on the Moon. An important difference between mountainouslandscapesMercury and the Moon is the presence on Mercury of numerous jagged slopes extending for hundreds of kilometers -scarps. The presence of well-preserved large craters on the surface of Mercurysuggests that over the past 3-4 billion years there was no movement of sections of the crust there on a large scale, and there was also nosurface erosion, the latter almost completely eliminating the possibility of the existence of any significant atmosphere in the history of Mercury.

Venus.

The average distance of Venus from the Sun is 108 millionkm(0,723 ). Distance from Venus tovaries from 40 to 259 million km. Hervery close to circular -is only 0.0068. The period of revolution around the Sun is 224.7 Earth days; average orbital speed -35 km/s. Venus rotates around its axis, tilted 2° from the perpendicular to the orbital plane, from east to west, that is, in the direction opposite to the direction of rotation of most planets. One rotation around its axis takes 243.02 Earth days. Venus is quite close in size to Earth. The planet's radius is 6051.8 km (95% of Earth's), mass - 4.87 10 24 kg (81.5% earthly), average density- 5.24 g/cm. Surface layer(bark) very thin; weakened by high temperature, it weakly prevents the lava from breaking out. Impact craters are a rare element of the Venusian landscape. There are only about 1,000 craters on the entire planet. The atmosphere on Venus was discoveredM. V. Lomonosovduringtransit of Venus across the disk of the SunJune 61761 (new style). The atmosphere of Venus consists mainly of carbon dioxide(96%) and nitrogen (almost 4%). Water vapor and oxygen are contained in it in trace amounts (0.02% and 0.1%). The Venusian atmosphere contains 105 times more gas than Earth's.Pressureat the surface reaches 93 atm, temperature - 750 K (475 °C). This exceeds the surface temperature of Mercury, which is twice as close to the Sun. The reason for such high temperatures on Venus isthe greenhouse effect created by a dense carbon dioxide atmosphere. The density of the atmosphere of Venus at the surface is only 14 times less than the density of water. Despite the slow rotation of the planet, there is no temperature difference between the day and night sides of the planet - it is so great thermal inertia atmosphere.

Mars.

Mars has two natural satellites - Phobos And Deimos , which are relatively small and have an irregular shape.The mass of Mars is 10.7% of the mass of the Earth (6.423 10 23 kg versus 5.9736 10 24 kg for the Earth), volume - 0.15 of the Earth's volume, and average linear diameter - 0.53 of the Earth's diameter (6800 km). The topography of Mars has many unique features. Mars has a rotation period andchange of seasonssimilar to Earth's, but its climatemuch colder and drier than on Earth. Temperatures on the planet range from−153 °Cat the pole in winter and up to more+20 °Conequatorat noon. average temperature is −50 °C. The atmosphere of Mars, consisting mainly ofcarbon dioxide, very rarefied.Pressureat the surface of Mars it is 160 times less than on Earth - 6.1mbarat average surface level. Due to the large difference in altitude on Mars, the pressure at the surface varies greatly. The approximate thickness of the atmosphere is 110 km. Two-thirds of the surface of Mars is occupied by light areas called continents, about a third are dark areas called seas. The seas are concentrated mainly in the southern hemisphere of the planet, between 10 and 40 °latitude. There are only two large seas in the northern hemisphere -AcidalianAndGreater Sirte. The nature of the dark areas is still a matter of debate. They persist despite the rage on Marsdust storms. At one time, this served as an argument in favor of the assumption that the dark areas were covered with vegetation. Now it is believed that these are simply areas from which, due to their topography, dust is easily blown away. Large-scale images show that the dark areas actually consist of groups of dark streaks and spots associated with craters, hills and other obstacles in the path of winds. Seasonal and long-term changes in their size and shape are apparently associated with a change in the ratio of surface areas covered with light and dark matter.

Earth.

Scientific evidence indicates that the Earth was formed from solar nebula about 4.54 billion years ago and soon after that acquired your only one natural satellite - Moon. Presumably life appeared on Earth approximately 3.9 billion years ago, that is, during the first billion after its origin. Since then biosphere The earth has changed significantly atmosphere and others abiotic factors, causing quantitative growth aerobic organisms, as well as the formationozone layer, which together with Earth's magnetic field weakens solar radiation harmful to life, thereby preserving the conditions for the existence of life on Earth. Bark The earth is divided into several segments, or tectonic plates, which move along the surface at speeds of the order of several centimeters per year.It is the largest of the four terrestrial planets in the Solar System, both in size and mass. The Earth's interior is divided into layers according to chemical and physical (rheological) properties, but unlike other terrestrial planets, the Earth has a pronounced externalAndinner core. Outer layer The earth is a hard shell consisting mainly of silicates. Frommantleit is separated by a border with a sharp increase in speedslongitudinalseismic waves -Mohorovicic surface. Significant changes in the crystal structure of the mantle occur at a depth of 410-660 km below the surface, encompassing the transition zone that separates the upper and lower mantle. Under the mantle there is a liquid layer consisting of molten iron with impuritiesnickel,sulfurand silicon -Earth's core.On sea ​​levelthe atmosphere exerts on the earth's surface pressure, equal to 1 atm (101.325 kPa). Average density air at the surface - 1.22 g/l. The Earth takes an average of 23 hours 56 minutes and 4.091 seconds (sidereal day) to make one revolution around its axis. Speed rotation planets from west to east is approximately 15 degrees per hour.

Terrestrial planets Terrestrial planets 4 planets of the solar system: Mercury, Venus, Earth and Mars. In structure and composition, some stony asteroids are close to them, for example, Vesta. Terrestrial planets have a high density and... ... Wikipedia

PLANETS AND SATELLITES. The 9 large planets of the solar system are divided into terrestrial planets (Mercury... Physical encyclopedia

Planets suitable for the emergence of life Theoretical dependence of the zone of location of planets suitable for supporting life (highlighted in green) on the type of star. The orbital scale is not respected... Wikipedia

4 planets of the solar system: Jupiter, Saturn, Uranus, Neptune; located outside the ring of minor planets. Compared to the solid-state planets of the terrestrial group (inner), they are all gas planets, have large sizes, masses ... Wikipedia

Planets- Planets. PLANETS, the most massive bodies of the Solar System, moving in elliptical orbits around the Sun (see Kepler's laws). 9 planets are known. The so-called terrestrial planets (Mercury, Venus, Earth, Mars) have solid... ... Illustrated encyclopedic Dictionary

- (from the Greek planetes wandering) the most massive bodies of the Solar system, moving in elliptical orbits around the Sun (see Kepler's laws), glow by reflected sunlight. The location of the planets in the direction from the Sun: Mercury, Venus, ... ... Big Encyclopedic Dictionary

Earth Photograph of Earth from Apollo 17 Orbital characteristics Aphelion 152,097,701 km 1.0167103335 a. e... Wikipedia

For giant planets outside the solar system, see Gas planet ... Wikipedia

- (from the Greek planētēs wandering), massive celestial bodies moving around the Sun in elliptical orbits (see Kepler's laws) and glowing by reflected sunlight. The location of the planets in the direction from the Sun: Mercury, Venus, Earth, Mars... encyclopedic Dictionary

Planets of the Solar System: Jupiter, Saturn, Uranus, Neptune; located outside the ring of minor planets (See Minor planets). Compared to the terrestrial (inner) planets, they have larger sizes, masses, a lower average ... Great Soviet Encyclopedia

Books

• Space. From the Solar System deep into the Universe, Mikhail Yakovlevich Marov. The book sets out in a fairly concise and popular form modern ideas about space and the bodies inhabiting it. This is, first of all, the Sun and the Solar System, the terrestrial planets and...

Space has long attracted people's attention. Astronomers began studying the planets of the Solar System back in the Middle Ages, examining them through primitive telescopes. But a thorough classification and description of the structural features and movements of celestial bodies became possible only in the 20th century. With the advent of powerful equipment equipped with last word observatory technology and spaceships Several previously unknown objects were discovered. Now every schoolchild can list all the planets of the solar system in order. I fell for almost all of them space probe, and man has only visited the Moon so far.

What is the Solar System

The Universe is huge and includes many galaxies. Our Solar System is part of a galaxy containing more than 100 billion stars. But there are very few that are like the Sun. Basically, they are all red dwarfs, which are smaller in size and do not shine as brightly. Scientists have suggested that the solar system was formed after the emergence of the Sun. His huge field attraction captured a gas-dust cloud, from which, as a result of gradual cooling, particles formed solid. Over time, celestial bodies were formed from them. It is believed that the Sun is now in the middle of its life path, therefore, it, as well as all the celestial bodies dependent on it, will exist for several more billions of years. Near space has been studied by astronomers for a long time, and any person knows what planets of the solar system exist. Photos of them taken with space satellites, can be found on the pages of various information resources dedicated to this topic. All celestial bodies are held by the strong gravitational field of the Sun, which makes up more than 99% of the volume of the Solar System. Large celestial bodies rotate around the star and around its axis in one direction and in one plane, which is called the ecliptic plane.

Planets of the Solar System in order

In modern astronomy, it is customary to consider celestial bodies starting from the Sun. In the 20th century, a classification was created that includes 9 planets of the solar system. But recent space exploration and newest discoveries prompted scientists to revise many provisions in astronomy. And in 2006 on international congress, due to its small size (a dwarf with a diameter not exceeding three thousand km), Pluto was excluded from the number of classical planets, and there were eight of them left. Now the structure of our solar system has taken on a symmetrical, slender appearance. It includes the four terrestrial planets: Mercury, Venus, Earth and Mars, then comes the asteroid belt, followed by the four giant planets: Jupiter, Saturn, Uranus and Neptune. On the outskirts of the solar system there is also a space that scientists call the Kuiper Belt. This is where Pluto is located. These places are still little studied due to their remoteness from the Sun.

Features of the terrestrial planets

What allows us to classify these celestial bodies as one group? Let us list the main characteristics of the inner planets:

• relatively not big sizes;
• hard surface, high density and similar composition (oxygen, silicon, aluminum, iron, magnesium and other heavy elements);
• presence of atmosphere;
• identical structure: a core of iron with nickel impurities, a mantle consisting of silicates, and a crust of silicate rocks (except for Mercury - it has no crust);
• a small number of satellites - only 3 for four planets;
• rather weak magnetic field.

Features of the giant planets

As for the outer planets, or gas giants, they have the following similar characteristics:

• large sizes and weights;
• they do not have a solid surface and consist of gases, mainly helium and hydrogen (therefore they are also called gas giants);
• liquid core consisting of metallic hydrogen;
• high rotation speed;
• a strong magnetic field, which explains the unusual nature of many processes occurring on them;
• there are 98 satellites in this group, most of which belong to Jupiter;
• the most characteristic feature gas giants are the presence of rings. All four planets have them, although they are not always noticeable.

The first planet is Mercury

It is located closest to the Sun. Therefore, from its surface the star appears three times larger than from the Earth. This also explains the strong temperature changes: from -180 to +430 degrees. Mercury moves very quickly in its orbit. Maybe that's why it got such a name, because in Greek mythology Mercury is the messenger of the gods. There is practically no atmosphere here and the sky is always black, but the Sun shines very brightly. However, there are places at the poles where its rays never hit. This phenomenon can be explained by the tilt of the rotation axis. No water was found on the surface. This circumstance, as well as the abnormally high daytime temperature (as well as the low nighttime temperature) fully explain the fact of the absence of life on the planet.

Venus

If you study the planets of the solar system in order, then Venus comes second. People could observe it in the sky back in ancient times, but since it was shown only in the morning and evening, it was believed that these were 2 different objects. By the way, our Slavic ancestors called it Mertsana. It is the third brightest object in our solar system. People used to call it the morning and evening star, because it is best visible before sunrise and sunset. Venus and Earth are very similar in structure, composition, size and gravity. This planet moves very slowly around its axis, making a full revolution in 243.02 Earth days. Of course, conditions on Venus are very different from those on Earth. It is twice as close to the Sun, so it is very hot there. Heat It is also explained by the fact that thick clouds of sulfuric acid and an atmosphere of carbon dioxide create a greenhouse effect on the planet. In addition, the pressure at the surface is 95 times greater than on Earth. Therefore, the first ship that visited Venus in the 70s of the 20th century stayed there for no more than an hour. Another peculiarity of the planet is that it rotates in the opposite direction compared to most planets. Astronomers still know nothing more about this celestial object.

Third planet from the Sun

The only place in the Solar System, and indeed in the entire Universe known to astronomers, where life exists is Earth. In the terrestrial group it has the largest size. What else are her

1. The highest gravity among the terrestrial planets.
2. Very strong magnetic field.
3. High density.
4. It is the only one among all the planets that has a hydrosphere, which contributed to the formation of life.
5. It has the largest satellite compared to its size, which stabilizes its tilt relative to the Sun and influences natural processes.

The planet Mars

This is one of the smallest planets in our Galaxy. If we consider the planets of the solar system in order, then Mars is the fourth from the Sun. Its atmosphere is very rarefied, and the pressure on the surface is almost 200 times less than on Earth. For the same reason, very strong temperature changes are observed. The planet Mars has been little studied, although it has long attracted the attention of people. According to scientists, this is the only celestial body on which life could exist. After all, in the past there was water on the surface of the planet. This conclusion can be drawn from the fact that there are large ice caps at the poles, and the surface is covered with many grooves, which could be dried up river beds. In addition, there are some minerals on Mars that can only be formed in the presence of water. Another feature of the fourth planet is the presence of two satellites. What makes them unusual is that Phobos gradually slows down its rotation and approaches the planet, while Deimos, on the contrary, moves away.

What is Jupiter famous for?

The fifth planet is the largest. The volume of Jupiter would fit 1300 Earths, and its mass is 317 times that of Earth. Like all gas giants, its structure is hydrogen-helium, reminiscent of the composition of stars. Jupiter is the most interesting planet, which has many characteristic features:

• it is the third brightest celestial body after the Moon and Venus;
• Jupiter has the strongest magnetic field of any planet;
• it completes a full revolution around its axis in just 10 Earth hours - faster than other planets;
• An interesting feature of Jupiter is the large red spot - this is how an atmospheric vortex rotating counterclockwise is visible from Earth;
• like all giant planets, it has rings, although not as bright as Saturn’s;
• this planet has the largest number of satellites. He has 63 of them. The most famous are Europa, where water was found, Ganymede is the most large satellite the planets Jupiter, as well as Io and Calisto;
• Another feature of the planet is that in the shadow the surface temperature is higher than in places illuminated by the Sun.

Planet Saturn

It is the second largest gas giant, also named after the ancient god. It is composed of hydrogen and helium, but traces of methane, ammonia and water have been found on its surface. Scientists have found that Saturn is the rarest planet. Its density is less than that of water. This gas giant rotates very quickly - it makes one revolution in 10 Earth hours, as a result of which the planet is flattened from the sides. Huge speeds on Saturn and the wind - up to 2000 kilometers per hour. This is faster than the speed of sound. Saturn has another one distinctive feature- it holds 60 satellites in its field of attraction. The largest of them, Titan, is the second largest in the entire solar system. The uniqueness of this object lies in the fact that by examining its surface, scientists for the first time discovered a celestial body with conditions similar to those that existed on Earth about 4 billion years ago. But the most main feature Saturn is the presence of bright rings. They circle the planet around the equator and reflect more light than the planet itself. Four is the most amazing phenomenon in the Solar System. What's unusual is that the inner rings move faster than the outer rings.

- Uranus

So, we continue to consider the planets of the solar system in order. The seventh planet from the Sun is Uranus. It is the coldest of all - the temperature drops to -224 °C. In addition, scientists did not find metallic hydrogen in its composition, but found modified ice. Therefore, Uranus is classified as a separate category ice giants. Amazing Feature of this celestial body is that it rotates while lying on its side. The change of seasons on the planet is also unusual: as many as 42 earthly years Winter reigns there, and the Sun does not appear at all; summer also lasts 42 years, and the Sun does not set at this time. In spring and autumn, the star appears every 9 hours. Like all giant planets, Uranus has rings and many satellites. As many as 13 rings revolve around it, but they are not as bright as those of Saturn, and the planet contains only 27 satellites. If we compare Uranus with the Earth, then it is 4 times larger than it, 14 times heavier and is located at a distance from the Sun of 19 times the path to the star from our planet.

Neptune: the invisible planet

After Pluto was excluded from the number of planets, Neptune became the last from the Sun in the system. It is located 30 times further from the star than the Earth, and is not visible from our planet even with a telescope. Scientists discovered it, so to speak, by accident: observing the peculiarities of the movement of the planets closest to it and their satellites, they concluded that there must be another large celestial body beyond the orbit of Uranus. After discovery and research it became clear interesting features of this planet:

• due to the presence of a large amount of methane in the atmosphere, the color of the planet from space appears blue-green;
• Neptune's orbit is almost perfectly circular;
• the planet rotates very slowly - it makes one circle every 165 years;
• Neptune is 4 times larger than Earth and 17 times heavier, but the force of gravity is almost the same as on our planet;
• the largest of the 13 satellites of this giant is Triton. It is always turned to the planet with one side and slowly approaches it. Based on these signs, scientists suggested that it was captured by the gravity of Neptune.

Throughout the galaxy Milky Way- about one hundred billion planets. So far, scientists cannot study even some of them. But the number of planets in the solar system is known to almost all people on Earth. True, in the 21st century, interest in astronomy has faded a little, but even children know the names of the planets of the solar system.

Dwarf planets like Ceres and Pluto, as well as others large asteroids They are similar to terrestrial planets in that they have a solid surface. However, they consist more of ice materials than stone.

Terrestrial exoplanets

Most of the planets discovered outside the solar system have been gas giants because they are the easiest to detect. But since 2005, hundreds of potential terrestrial exoplanets have been discovered, thanks in large part to the Kepler space mission. Most planets became known as "super-Earths" (that is, planets with masses between Earth and Neptune).

Examples of terrestrial exoplanets, a planet with a mass of 7-9 terrestrials. This planet orbits the red dwarf star Gliese 876, located 15 light-years from Earth. The existence of three (or four) terrestrial exoplanets was also confirmed between 2007 and 2010 in the system of Gliese 581, another red dwarf approximately 20 light-years from Earth.

The smallest of them, Gliese 581 e, is only 1.9 Earth's mass, but orbits too close to the star. The other two, Gliese 581 c and Gliese 581 d, as well as the proposed fourth planet Gliese 581 g, are more massive and orbit within the "" star. If this information is confirmed, the system will become interesting for the presence of potentially habitable terrestrial planets.

The first confirmed terrestrial exoplanet, Kepler-10b, a 3-4 Earth mass planet located 460 light-years from Earth, was discovered in 2011 by the Kepler mission. That same year, the Kepler Space Observatory released a list of 1,235 exoplanetary candidates, including six “super-Earths” located within the potentially habitable zone of their star.

Since then, Kepler has discovered hundreds of planets ranging in size from the Moon to big Earth, and even more candidates outside these sizes.

Scientists have proposed several categories for classifying terrestrial planets. Silicate planets- This is the standard type of terrestrial planet in the Solar System, consisting primarily of a silicate solid mantle and a metallic (iron) core.

Iron planets is a theoretical type of terrestrial planet that is composed almost entirely of iron, and is therefore denser and has a smaller radius than other planets of comparable mass. These types of planets are thought to form in high-temperature regions close to the star, where the protoplanetary disk is rich in iron. Mercury may be an example of such a group: it formed close to the Sun and has a metallic core that is equivalent to 60-70% of the planetary mass.

Planets without a core- another theoretical type of terrestrial planets: they are composed of silicate rocks, but do not have a metallic core. In other words, planets without a core are the opposite of an iron planet. Planets without cores are thought to form further from the star, where the volatile oxidizer is more abundant. And although we do not have such planets, there are a lot of chondrites - asteroids.

Finally there is carbon planets(so-called "diamond planets"), a theoretical class of planets that consist of a metallic core surrounded primarily by carbon-based minerals. Again, there are no such planets in the Solar System, but there are an abundance of carbon-rich asteroids.

Until recently, everything that scientists knew about planets - including their formation and presence different types, - emerged from the study of our own solar system. But with the development of exoplanet research, which has seen a huge surge in the last ten years, our knowledge of the planets has increased significantly.

On the one hand, we have come to understand that the size and scale of planets is much larger than previously thought. Moreover, this is the first time we have seen many Earth-like planets (which may also be habitable) existing in other solar systems.

Who knows what we will find when we are able to send probes and manned missions to other terrestrial planets?