The planets of the terrestrial group, their features and characteristics. Brief description of the terrestrial planets
> Planets of the Earth group
planets terrestrial group - the first four planets of the solar system with a photo. Find out the characteristics and description of the planets earth type, search for exoplanets, research.
Researchers have been studying the expanses of the solar system for many centuries, noting various planetary types. Since the discovery of access to exoplanets, our information base has become even wider. In addition to gas giants, we also found terrestrial objects. What is this?
Definition of terrestrial planets
terrestrial planet- a celestial body, represented by silicate rocks or metal, and has a solid surface layer. This is the main difference from gas giants filled with gases. The term is taken from the Latin word "Terra", which translates as "Earth". Below is a list of what are the terrestrial planets.
The structure and features of the planets of the Earth group
All bodies are endowed with a similar structure: a core of metal filled with iron and surrounded by a mantle of silicates. Their surface ball is covered with craters, volcanoes, mountains, canyons and other formations.
There are secondary atmospheres created by volcanic activity or the arrival of comets. They have a small number of satellites or are completely devoid of such features. Earth has the Moon, and Mars has Phobos and Deimos. Not endowed with ring systems. Let's see how the characteristics of the terrestrial planets look like, and also notice what their similarities and differences are on the example of Mercury, Venus, Earth and Mars.
Basic facts of the terrestrial planets
Mercury- the smallest planet in the system, reaching 1/3 of the earth's size. It is endowed with a thin atmospheric layer, which is why it constantly freezes and heats up. It is characterized by high density with iron and nickel. The magnetic field reaches only 1% of the earth's. Many deep crater scars and a faint layer of silicate particles are visible on the surface. In 2012, traces of organic material were noticed. These are the building blocks for life and also found water ice.
Venus similar in size to the Earth, but its atmosphere is too dense and filled with carbon monoxide. Because of this, heat is retained on the planet, making it the hottest in the system. Most of the surface has active volcanoes and deep canyons. Only a few vehicles managed to penetrate the surface and survive for a short period of time. There are few craters because meteors burn up.
Earth- the largest in the terrestrial type and has huge amount liquid water. It is necessary for life, which develops in all forms. There is a rocky surface covered with canyons and uplands, as well as a heavy metal core. Water vapor is present in the atmosphere, which contributes to the mitigation of the daily temperature regime. There are regular seasons. The greatest heating goes to areas near the equatorial line. But now the numbers are rising due to human activity.
Mars has the highest mountain in the solar system. Most of surface is represented by ancient deposits and crater formations. But you can find younger sites. There are polar caps that shrink in summer and spring periods. It is inferior to the Earth in density, and the core is solid. Researchers have not yet obtained evidence of life, but there are all hints and conditions in the past. The planet has water ice, organics and methane.
Formation and common features of the planets of the Earth group
It is believed that terrestrial planets appeared first. Initially, dust particles merged, creating large objects. They were located closer to the Sun, so volatile substances evaporated. Celestial objects grew to a kilometer size, becoming planetesimals. Then they accumulate more and more dust.
The analysis shows that at an early stage in the development of the solar system, about a hundred protoplanets could have been present, whose sizes varied between the Moon and Mars. They constantly collided, due to which they merged, throwing out garbage fragments. As a result, 4 large planets of the terrestrial group survived: Mercury, Venus, Mars and Earth.
All of them are distinguished by a high density index, and the composition is represented by silicates and metallic iron. The largest representative of the terrestrial type is the Earth. These planets are also distinguished overall structure structure, including the core, mantle and crust. Only two planets (Earth and Mars) have moons.
Current research on the Terrestrial planets
Researchers believe that terrestrial planets are the best candidates for discovering life. Of course, the conclusions are based on the fact that the only planet with life is the Earth, so its characteristics and features serve as a kind of standard.
Everything suggests that life is able to survive in extreme conditions. Therefore, it is expected to be found even on Mercury and Venus, despite their high temperatures. Most attention is paid to Mars. This is not only a prime candidate for finding life, but also a potential future colony.
If everything goes according to plan, then in the 2030s. the first batch of astronauts can be sent to the Red Planet. Now the planet is constantly rovers and orbiters looking for water and signs of life.
Earth-like exoplanets
Many exoplanets found have turned out to be gas giants because they are much easier to find. But since 2005, we began to actively capture terrestrial objects thanks to the Kepler mission. Most of it was called the super-earth class.
Among these, it is worth remembering Gliese 876d, whose mass is 7-9 times greater than the earth. It orbits a red dwarf, 15 light-years distant from us. In the Gliese 581 system, 3 terrestrial exoplanets were found with a distance of 20 light years.
The smallest is Gliese 581e. It exceeds our mass by only 1.9 times, but is located extremely close to its star. The first confirmed terrestrial exoplanet was Kepler-10b, 3-4 times our mass. It is 460 light years distant and was found in 2011. At the same time, the mission team issued a list of 1235 applicants, where 6 were of the terrestrial type and were located in the habitable zone.
super earth
Among the exoplanets managed to find many super-Earths (in size between Earth and Neptune). This species is not found in the territory of our system, so it is not yet clear whether they look more like giants or terrestrial types.
Now the scientific world is waiting for the launch of the James Webb telescope, which promises to increase the power of the search and reveal to us the depths of space.
Categories of terrestrial planets
There is a division of terrestrial planets. Silicate - typical objects of our system, represented by a stone mantle and a metal core. Iron - a theoretical variety consisting entirely of iron. This gives a greater density index, but reduces the radius. Such planets can only appear in areas with a high temperature index.
Rocky - Another theoretical species, where there is a silicate rock, but no metal core. They should form away from the star. Carbonaceous - endowed with a metal core, around which a carbon-containing mineral has accumulated.
We used to think that we had studied in detail the process of planetary formation. But the consideration of exoplanets forces us to find many gaps and start new research. This also expands the conditions for the search for life in alien worlds. Who knows what we'll see there if we can send a probe.
The terrestrial planets are the four planets of the solar system: Mercury, Venus, Earth and Mars. They are located in the inner region of the solar system, unlike the giant planets located in the outer region. According to a number of cosmogonic theories, in a significant part of extrasolar planetary systems, exoplanets are also divided into solid planets in the inner regions and gas planets in the outer ones. In terms of structure and composition, some stone asteroids, for example, Vesta, are close to the terrestrial planets.
Main characteristics
The terrestrial planets are highly dense and composed predominantly of silicates and metallic iron (unlike gaseous planets and rock-ice dwarf planets, Kuiper belt objects and the Oort cloud). The largest terrestrial planet - Earth - is more than 14 times less massive than the least massive gas planet - Uranus, but about 400 times more massive than the largest known Kuiper belt object.
The terrestrial planets are composed mainly of oxygen, silicon, iron, magnesium, aluminum and other heavy elements.
All terrestrial planets have the following structure:
- In the center is a core made of iron with an admixture of nickel.
- The mantle is composed of silicates.
- A 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. The Earth differs from other terrestrial planets by a high degree of chemical differentiation of matter and by 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 (unlike all giant planets) have rings.
Lecture: Solar system: terrestrial planets and giant planets, small bodies solar system
The solar system is made up of various kinds of bodies. The main one, of course, is the sun. But if you do not take it into account, then the planets are considered the main elements of the solar system. They are the second most important elements after the sun. The solar system itself bears this name due to the fact that the sun plays here key role because all the planets revolve around the sun.
terrestrial planets
There are currently two groups of planets in the solar system. The first group is the terrestrial planets. These include Mercury, Venus, Earth, and Mars. IN this list they are all listed based on the distance from the Sun to each of these planets. They got their name due to the fact that their properties are somewhat reminiscent of the characteristics of the planet Earth. All terrestrial planets have a solid surface. A feature of each of these planets is that they all rotate around their own axis in different ways. For example, for the Earth, one revolution of a complete rotation occurs during the day, that is, 24 hours, while for Venus, a complete rotation occurs in 243 Earth days.
Each of the terrestrial planets has its own atmosphere. It is different in terms of density and composition, but it definitely exists. For example, in Venus it is quite dense, while in Mercury it is almost invisible. In fact, at the moment there is an opinion that Mercury has no atmosphere at all, however, in fact, this is not so. All the atmospheres of the planets of the terrestrial group consist of substances whose molecules are relatively heavy. For example, the atmosphere of Earth, Venus and Mars is composed of carbon dioxide and water vapor. In turn, the atmosphere of Mercury consists mainly of helium.
In addition to the atmosphere, all terrestrial planets have approximately the same chemical composition. In particular, they consist predominantly of silicon compounds, as well as iron. However, there are other elements in the composition of these planets, but their number is not so large.
A feature of the terrestrial planets is that in their center there is a core of various masses. At the same time, all the nuclei are in a liquid state - the only exception is, presumably, only Venus.
Each of the terrestrial planets has its own magnetic fields. At the same time, on Venus their influence is almost imperceptible, while on the Earth, Mercury and Mars they are quite noticeable. As for the Earth, its magnetic fields do not stand still, but move. And although their speed is extremely small compared to human notions, scientists suggest that the movement of fields can further lead to a change in magnetic belts.
Another feature of the terrestrial planets is that they have practically no natural satellites. In particular, to date they have been found only near the Earth and Mars.
giant planets
The second group of planets is called "giant planets". These include Jupiter, Saturn, Uranus and Neptune. By their mass, they significantly exceed the mass of the planets of the terrestrial group.
The lightest giant to date is Uranus, however, its mass exceeds the mass of the earth
about 14 and a half times. And the heaviest planet in the solar system (with the exception of the Sun) is Jupiter.
None of the giant planets actually have their own surface, since they are all in a gaseous state. The gases of which these planets are composed, as they approach the center or equator, as it is called, pass into a liquid state. In this regard, one can notice the difference in the features of the rotation of the giant planets around their own axis. It should be noted that the duration of a complete rotation is a maximum of 18 hours. Meanwhile, each layer of the planet rotates around its axis at a different speed. This feature is due to the fact that the giant planets are not solid. In this regard, their individual parts, as it were, are not interconnected.
At the center of all giant planets is a solid core of small size. Most likely, one of the main substances of these planets is hydrogen, which has metallic characteristics. Thanks to this, at the moment it has been proven that the giant planets have their own magnetic field. However, in science at the moment there is very little convincing evidence and a lot of contradictions that could characterize the giant planets.
Their distinctive feature is that such planets have many natural satellites, as well as rings. Rings in this case are called small clusters of particles that rotate directly around the planet and collect various kinds of small particles flying past.
To date, science officially knows only 9 major planets. However, only eight are included in the composition of the terrestrial planets and giant planets. The ninth planet, which is Pluto, does not fit into any of the listed groups, since it is located at a very distant distance from the Sun and is practically not studied. The only thing that can be said about Pluto is that its state is close to solid. At the moment, there is an assumption that Pluto is not a planet at all. This assumption exists for more than 20 years, but the decision to exclude Pluto from the composition of the planets has not yet been made.
Small bodies of the solar system
In addition to the planets in the solar system, there are a lot of all kinds of relatively small bodies in their weight, which are called asteroids, comets, minor planets, and so on. In general, the data celestial bodies belong to the group of small celestial bodies. They differ from the planets in that they have a solid state, are relatively small in size and can move around the Sun not only in the forward but also in the opposite direction. Their size is much smaller than any of the planets discovered to date. Losing cosmic attraction, small celestial bodies of the solar system fall into the upper layers of the earth's atmosphere, where they burn out or fall in the form of meteorites. The change in the state of bodies revolving around other planets has not yet been studied.
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Reshebnik in astronomy grade 11 for lesson number 13 ( workbook) - terrestrial planets
1. Using the reference data of the textbook, fill in the table with the main physical characteristics of the terrestrial planets.
Physical characteristics of the planets | Mercury | Venus | Earth | Mars |
Mass (in Earth masses) | 0.055 | 0.815 | 1 | 0.107 |
Diameter (in Earth diameters) | 0.382 | 0.949 | 1 | 0.533 |
Density, kg/m^3 | 5440 | 5240 | 5520 | 3940 |
Rotation period | 58.6 days | 243 days | 23 h 56 min | 24 h 37 min |
Atmosphere: pressure, chemical composition | Hardly ever | 95 atm, 96.5% CO(2), 3.5% N(2), etc. | 1 atm, 78% N(2), 21% O(2), etc. | 1/150 atm, 95% CO(2), 2.5% N(2), etc. |
Surface temperature, °C | +430 during the day; -170 at night | +480 | From +60 to +17 during the day; -80 at night | From +15 to -60 during the day; -120 at night |
Number of satellites | - | - | 1 | 2 |
Satellite names | - | - | Moon | Phobos and Deimos |
Fill in the table, draw conclusions and indicate the similarities and differences between the terrestrial planets.
Conclusions: Almost all terrestrial planets have the same planes of similar masses. The terrestrial planets, except for Mercury, have an atmosphere.
2. The graphs show the dependences of pressure and temperature in the atmosphere of Venus. Based on the analysis of the graphs, answer the questions.
At what altitude is the atmospheric pressure of Venus equal to the atmospheric pressure at the Earth's surface? (Approximately 50 km.)
What is the temperature of Venus's atmosphere at this altitude? (About 330K, or +50 °C.)
3. Using the picture, describe the internal structure of the Earth.
4. Complete the sentences.
Option 1.
The planet Mercury has the largest difference between day and night surface temperatures.
high temperature The surface of Venus is caused by the greenhouse effect.
The terrestrial planet with an average surface temperature below 0 °C is Mars.
Most of the surface is covered with water near the planet Earth.
The composition of the clouds includes droplets of sulfuric acid near the planet Venus.
Option 2.
The planet with a diurnal surface temperature difference of about 100 °C is Mars.
The planets with surface temperatures above +400 °C are Mercury and Venus.
The planet in whose atmosphere global dust storms often occur is Mars.
The planet Mercury has virtually no atmosphere.
The planet that has a biosphere is Earth.
5. What physical characteristics of the planet do you need to know in order to calculate its average density?
You need to know the mass of the planet and its average radius. The average density is determined by dividing the mass by the volume of the planet.
The solar system is the only planetary structure available to us for direct study. The information obtained on the basis of research in this area of space is used by scientists to understand the processes taking place in the Universe. They make it possible to understand how our system was born and similar to it, what future awaits us all.
Classification of the planets of the solar system
Research by astrophysicists has made it possible to classify the planets of the solar system. They were divided into two types: terrestrial and gas giants. The terrestrial planets include Mercury, Venus, Earth, Mars. The gas giants are Jupiter, Saturn, Uranus and Neptune. Pluto has received status since 2006 dwarf planet and refers to the Kuiper belt objects, which differ in their features from the representatives of both named groups.
Characteristics of the terrestrial planets
Each type has a set of features associated with internal structure and composition. The high average density and the predominance of silicates and metals at all levels are the main characteristics that distinguish the terrestrial planets. Giants, in contrast, have a low density and consist primarily of gases.
All four planets have a similar internal structure: under the solid crust is a viscous mantle that envelops the core. The central structure, in turn, is divided into two levels: liquid and solid core. Its main constituents are nickel and iron. The mantle differs from the core in the predominance of manganese.
The sizes of the planets of the solar system belonging to the terrestrial group are distributed in this way (from smallest to largest): Mercury, Mars, Venus, Earth.
air shell
Earth-like planets were already surrounded by an atmosphere at the first stages of their formation. Initially, its composition was dominated by the change in the atmosphere on Earth contributed to the emergence of life. The terrestrial planets are thus space bodies surrounded by atmosphere. However, among them there is one that has lost its air shell. This which is not allowed to maintain the primary atmosphere.
closest to the sun
The smallest terrestrial planet is Mercury. Its study is hampered by its proximity to the Sun. Since data on Mercury were received only from two devices: "Mariner-10" and "Messenger". Based on them, it was possible to create a map of the planet and determine some of its features.
Mercury can indeed be recognized as the smallest planet of the terrestrial group: its radius is a little less than 2.5 thousand kilometers. Its density is close to earth. The ratio of this indicator to the size suggests that the planet is largely composed of metals.
The movement of Mercury has a number of features. Its orbit is highly elongated: at the most distant point, the distance to the Sun is 1.5 times greater than at the nearest one. The planet makes one revolution around the star in about 88 Earth days. At the same time, in such a year, Mercury has time to turn around its axis only one and a half times. Such "behavior" is not typical for other planets in the solar system. Presumably, the slowdown of the initially faster movement was caused by the tidal influence of the Sun.
Beautiful and terrible
The terrestrial planets include both identical and different cosmic bodies. Similar in structure, they all have features that make them impossible to confuse. Mercury, which is closest to the Sun, is not the hottest planet. It even has areas that are forever covered with ice. Venus, following it in close proximity to the star, is characterized by higher temperatures.
Named after the goddess of love, the planet has long been a candidate for habitable space objects. However, the very first flights to Venus refuted this hypothesis. The true essence of the planet is hidden by a dense atmosphere consisting of carbon dioxide and nitrogen. Such an air shell contributes to the development of the greenhouse effect. As a result, the temperature on the surface of the planet reaches +475 ºС. Here, therefore, there can be no life.
The second largest and farthest planet from the Sun has a number of features. Venus is the most bright dot in the night sky after the moon. Its orbit is an almost perfect circle. It moves around its axis from east to west. This direction is not typical for most planets. It completes a revolution around the Sun in 224.7 Earth days, and around the axis - in 243, that is, a year here is shorter than a day.
Third planet from the Sun
The earth is unique in many ways. It is located in the so-called zone of life, where the sun's rays are not able to turn the surface into a desert, but there is enough heat so that the planet is not covered with an ice crust. A little less than 80% of the surface is occupied by the World Ocean, which, together with rivers and lakes, forms a hydrosphere that is absent on the rest of the planets of the solar system.
The development of life contributed to the formation of a special atmosphere of the Earth, consisting mainly of nitrogen and oxygen. As a result of an increase in oxygen concentration, a ozone layer, which together with magnetic field protects the planet from the damaging effects of solar radiation.
Earth's only satellite
The moon has a rather serious impact on the Earth. Our planet has natural companion almost immediately after its formation. remains a mystery, although there are several plausible hypotheses on this score. The satellite has a stabilizing effect on the tilt earth's axis and also causes the planet to slow down. As a result, each new day becomes a little longer. The slowdown is a consequence of the tidal action of the moon, the same force that causes in the ocean.
Red Planet
When asked which planets of the terrestrial group are best studied after ours, there is always an unambiguous answer: Mars. Due to their location and climate, Venus and Mercury have been studied to a much lesser extent.
If we compare the sizes of the planets of the solar system, then Mars will be in seventh place on the list. Its diameter is 6800 km, and its mass is 10.7% of that of the Earth.
The red planet has a very rarefied atmosphere. Its surface is dotted with craters, you can also see volcanoes, valleys and glacial polar caps. Mars has two satellites. The closest to the planet - Phobos - is gradually decreasing and will be torn apart by the gravity of Mars in the future. Deimos, on the contrary, is characterized by slow removal.
The idea of the possibility of life on Mars has been around for more than a century. Latest Research, conducted in 2012, found on the red planet It was suggested that organic matter could be brought to the surface by a rover from Earth. However, studies have confirmed the origin of the substance: its source is the red planet itself. Nevertheless, an unambiguous conclusion about the possibility of life on Mars cannot be made without additional research.
The terrestrial planets are the closest space objects to us in terms of location. That is why they are better studied today. Astronomers have already discovered several exoplanets, presumably also of this type. Of course, each such discovery increases the hope of finding life outside the solar system.