Message about 1 of the terrestrial planets. Differences between the terrestrial planets and other planets of the solar system. Planets are giants
Subdivided into 2 groups based on their planetary surfaces: gas giants and terrestrial planets. Terrestrial planets are characterized by a dense surface and, as a rule, consist of silicate compounds. There are only four such planets in the solar system: Mars, Earth, Venus and Mercury.
Terrestrial planets in the solar system:
Mercury
Mercury is the smallest of the four earth-like planets in the solar system with an equatorial radius of 2,439.7 ± 1.0 km. The planet is larger than satellites such as Titan. However, Mercury has the second highest density (5427 grams per cubic centimeter) among the planets in the solar system, slightly inferior in this indicator to Earth. The high density provides insight into the inner structure of the planet, which scientists believe is rich in iron. It is believed that the core of Mercury has the highest iron content of all the planets in our system. Astronomers believe that the molten core makes up 55% of the planet's total volume. The shell of the iron-rich core is the mantle, which is mainly composed of silicates. The rocky crust of the planet reaches 35 km in thickness. Mercury is 0.39 astronomical units from the Sun, making it the closest planet to our star. Due to its proximity to the Sun, the planet's surface temperature rises to over 400 ° C.
Venus
Venus is Earth's closest neighbor and one of the four terrestrial planets in the solar system. It is the second largest planet in this category with a diameter of 12,092 km; second only to the Earth. However, the thick atmosphere of Venus is considered the densest in the solar system, atmospheric pressure is 92 times higher than the atmospheric pressure on our planet. The dense atmosphere is made up of carbon dioxide, which has a greenhouse effect and causes the temperature on Venus's surface to rise to 462º C, and is. The planet is dominated by volcanic plains, covering about 80% of its surface. Venus also has numerous impact craters, some of which reach a diameter of about 280 km.
Earth
Of the four terrestrial planets, Earth is the largest with an equatorial diameter of 12,756.1 km. It is also the only planet in this group known to have a hydrosphere. The Earth is the third closest planet to the Sun, located at a distance of about 150 million km (1 astronomical unit) from it. The planet also has the highest density (5.514 grams per cubic centimeter) in the solar system. Silicate and alumina are the two compounds found in the highest concentrations in the earth's crust, accounting for 75.4% of the continental crust and 65.1% of the oceanic crust.
Mars
Mars is another terrestrial planet in the solar system, located farthest from the Sun at a distance of 1.5 astronomical units. The planet has an equatorial radius of 3396.2 ± 0.1 km, making it the second smallest planet in our system. The surface of Mars is mainly composed of basaltic rocks. The planet's crust is quite thick and ranges from 125 km to 40 km in depth.
Dwarf planets
There are other smaller dwarf planets that have some characteristics comparable to terrestrial planets, such as having a dense surface. However, the surface dwarf planets formed by ice and therefore do not belong to this group. Examples of dwarf planets in the solar system are Pluto and Ceres.
Mironova Elena 2 K. 2 gr.
The planets belonging to the terrestrial group - Mercury, Venus, Earth, Mars - are small in size and mass, the average density of these planets is several times higher than the density of water; they slowly revolve around their axes; they have few satellites (Mercury and Venus do not have them at all, Mars has two tiny ones, Earth has one). The similarity of the terrestrial planets does not exclude a significant difference. For example, Venus, unlike other planets, rotates in the direction opposite to its movement around the Sun, and is 243 times slower than the Earth (compare with the length of the year on Venus). The orbital period of Mercury (that is, the year of this planet) is only 1/3 longer than the period of its rotation around the axis (in relation to the stars). The angles of inclination of the axes to the planes of their orbits for the Earth and for Mars are approximately the same, but completely different for Mercury and Venus. And this is one of the reasons that determines the nature of the changing seasons. The seasons of the year are the same as those of the Earth, therefore, on Mars (although each season is almost twice as long as on Earth).
Similarities and differences are also found in the study of the atmospheres of the terrestrial planets. Unlike Mercury, which, like the Moon, is practically devoid of an atmosphere, Venus and Mars have it. Comparing the atmospheres of Venus and Mars with that of Earth, we see that, in contrast to the nitrogen-oxygen atmosphere of the Earth, Venus and Mars have atmospheres mainly consisting of carbon dioxide... the pressure at the surface of Venus is more than 90 times greater, and on Mars almost 150 times less than at the surface of the Earth.
Gas in the atmospheres of the terrestrial planets is in continuous motion. Often during dust storms that last for several months, a huge amount of dust rises into the atmosphere of Mars. Hurricane winds are recorded in the atmosphere of Venus at altitudes where the cloud layer is located (50 to 70 km above the planet's surface), but near the surface of this planet the wind speed reaches only a few meters per second. Thus, despite some similarities, in general, the atmospheres of the planets closest to the Earth differ sharply from the atmosphere of the Earth.
The terrestrial planets, like the Earth and the Moon, have hard surfaces. The surface of Mercury, teeming with craters, is very similar to the moon. There are fewer "seas" than on the Moon, and they are small. The rocky desert and many individual stones are visible in the first photo-television panoramas transmitted from the surface of Venus by automatic stations. The surface of Mars is also teeming with craters. There are especially many of them in the southern hemisphere of the planet. Dark areas that occupy a significant part of the planet's surface are called seas (Hellas, Argir, etc.). diameters of some seas exceed 2000 km.
[Levitan E.P. Astronomy. Textbook for grade 11, 1998]
Terrestrial planets (those that have a solid surface) are located within the asteroid belt located between the orbits of Mars and Jupiter. Therefore, they are also called the inner planets. These include Mercury, Venus, Earth, and Mars. A brief description of the terrestrial planets will be given below.
These planets, to a large extent, are composed of silicates and metallic iron, in contrast to. They also contain a lot of oxygen, magnesium, aluminum, silicon, iron and other heavy metals.
All inner planets have the same structure:
- in the very center there is a heavy and hot core. It mainly consists of iron, with an admixture of nickel;
- a mantle of silicates is located above the core;
- the uppermost layer is the crust formed due to the partial melting of the mantle. Therefore, it also consists of silicates enriched with other elements. Only Mercury has no crust - it was destroyed by strong meteorite bombardments, due to the highly discharged atmosphere. The earth's crust is very different from other planets, it is high in granite.
Two terrestrial planets have satellites (Earth and Mars).
The table below shows a sample characteristic of the terrestrial planets.
| Name of the planet | Mercury | Venus | Earth | Mars |
|---|---|---|---|---|
| Distance to the Sun, million km | 57,9 | 108,2 | 149,6 | 227,9 |
| Distance to the Sun, au | 0,24085 | 0,61521 | 1,00004 | 1,88078 |
| Orbit inclination, degrees | 7,005 | 3,395 | 0,0002 | 1,850 |
| Eccentricity | 0,20564 | 0,00676 | 0,01672 | 0,09344 |
| Period of revolution around its axis, days | 58,6 | 243,0 | 0,9973 | 1,026 |
| Orbital speed, km / s | 47,9 | 35,0 | 29,8 | 24,1 |
| Equator inclination to orbit, degree | 0,01 | 177,36 | 23,44 | 25,19 |
| Number of satellites, pcs. | - | - | 1 | 2 |
Mercury
Mercury is the smallest and closest planet to the Sun in the solar system. Its radius is 2439.7 km, weight - 3.3 10 23 kg. The average density of Mercury is slightly less than that of the Earth, and amounts to 5.43 g / cm 3. The acceleration due to gravity on the surface is 3.70 m / s 2.
Due to the highly elongated orbit of Mercury, its distance from the Sun varies from 45.9 million km. up to 69.7 million km.
Mercury, in its rotation, is a unique planet in the solar system. First of all, a day on it takes 2/3 of its own year. Those. in one Mercurian year there will only be a day and a half. This is explained by the strong tidal effect of the Sun on the planet. Another of its uniqueness lies in the fact that near perihelion (the point of the orbit closest to the Sun), during 8 Earth days, the angular velocity of movement in orbit exceeds the angular velocity of rotation of Mercury around its axis. As a result, in the Mercury sky, the Sun stops and starts moving in the opposite direction!
There are no seasons on Mercury due to the fact that the plane of its axis is almost at right angles to the plane of its own orbit. Through this fact, there are areas at the poles of the planet that sunlight does not reach.
The temperature on Mercury varies greatly, from -180 degrees (at night) to +430 degrees during the day. Because of this temperature, there is practically no atmosphere on the planet, and it is very rarefied.
Venus
It is often called the morning star. Venus can be observed with the naked eye, at dusk and dawn.
Venus is the sister of the Earth. They are very similar in size, density and mass. The radius is 6051.8 km, the mass is 4.87 10 24 kg. The average density is 5.24 g / cm 3, and the acceleration of gravity on the surface has a value of 8.87 m / s 2.
Venus has a very dense atmosphere (only 14 times less than the density of water), consisting of 96% carbon dioxide, almost 4% nitrogen, water vapor and oxygen make up 0.1%. Due to this density, the surface pressure is 93 atm. and a temperature of 475 degrees Celsius. This high temperature is due to the greenhouse effect. Moreover, the difference between day and night temperatures is not observed - the thermal inertia of the Venusian atmosphere is very high.
Earth
Our planet is truly a unique phenomenon in the solar system. The composition of its atmosphere, distance from the Sun, dimensions, periods of rotation - all this makes it possible for one of the most important elements of the existence of earthly life to exist. This is water in a liquid state.
The average radius of the Earth is 6371 km. The earth's mass is 5.9736 10 24 kg, the average density is 5.5153 g / cm 3, and the free fall speed is 9.780327 m / s 2.
The Earth's atmosphere is 78% nitrogen, 21% oxygen. The rest is occupied by carbon dioxide, argon and other elements.
The Earth has one natural satellite - the Moon.
Mars
Mars also calls the red planet, through its appearance. It's just that strong winds always blow on it and therefore, when observed, its soil gives a red tint.
The Martian radius is 3389.5 km. The mass has a value of 6.423 10 23 kg, the density is 3933 kg / m 3, and the acceleration due to gravity is 3.711 m / s 2.
Mars is home to the highest point in the solar system, the Olympus volcano, and the largest canyon in the solar system, the Mariner Valley.
The Martian atmosphere is 95% carbon dioxide, 2.7% nitrogen, 1.6% argon, oxygen only 0.13%. The pressure ranges from 0.4 kPa to 0.87 kPa.
Surface temperatures range from -85 degrees to -5 degrees Celsius.
There is a lot of controversy around Mars - does water exist there or not, was there life, or maybe it is still there? I hope that humanity will receive answers to these and other questions soon!
Mars has two natural moons - Deimos and Phobos.
This article does not provide a complete description of the terrestrial planets and each planet individually, and gives only a small idea of the above topic.
Astronomy answer book for 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 diameters of the Earth) | 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 mins | 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 in the afternoon; -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: The planets of the terrestrial group almost all have the same planes of close 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 pressure of the atmosphere of Venus atmospheric pressure near the surface of the earth? (Approximately 50 km.)
What is the temperature of the atmosphere of Venus at a given 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 due to the greenhouse effect.
A 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 clouds include droplets of sulfuric acid near the planet Venus.
Option 2.
A planet with a daily surface temperature difference of about 100 ° C is Mars.
Planets with surface temperatures above +400 ° C are Mercury and Venus.
The planet, in the atmosphere of which global dust storms often occur, is Mars.
The planet Mercury has practically no atmosphere.
The planet with the biosphere is the Earth.
5. What physical characteristics of the planet do you need to know in order to calculate its average density?
It is necessary 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.
There are four objects in the solar system, which are commonly called terrestrial planets: Mercury (the smallest), Venus and Mars, and the Earth (the largest). They are also called internal, solid, opposing the external gas giant planets.
General characteristics
The facts about the terrestrial planets mainly relate to 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 - the Earth.
It is known that these have a significant density, consist of iron and silicates, as well as oxygen, silicon, magnesium, 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 the mantle is located, which includes silicates. It is covered with a crust, which also consists of silicate rocks, but enriched with other elements. Mercury has no crust, which was, as scientists assume, the result of meteorite bombardment of a space object. Earth and Mars have satellites. Mercury and Venus do not have them.
Earthlike
Most scientists believe that the best conditions for the emergence of biological life exist precisely on the planets of this group. That is why the search and comprehensive study of these space objects is attracting increased attention of scientists from all countries. An example of terrestrial planets is the so-called super-earths. As of 2012, more than fifty of them were found. On each of them, according to scientists, the emergence of life is theoretically possible.
Facts about the terrestrial planets
But back to the solar system. Native Earth is the third from the Sun. It is the largest solid planet in terms of density, diameter, and mass. Let's learn a few facts about our planet:
- For today this is the only known to man cosmic bodies on which biological life has been found.
- 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.
- Together with magnetic field the ozone layer attenuates 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 a year!
- More than 70 percent of the planet's surface is water. Sushi accounts for less than 30 percent. Water is essential for all known living forms.
- The poles of the planet are sheltered by the Arctic ice and the Antarctic ice shield.
- According to some scientists, the Earth can maintain the conditions for the life of biological organisms for a rather long period of time: more than two billion years. Unless, of course, you do not try to artificially violate these conditions (as a result of destructive and thoughtless human activity and its impact on the biosphere).
- Our planet orbits the Sun in about 365.26 days, which is a sidereal year.
- The moon, a satellite of the Earth, causes the phenomenon of tide, and also stabilizes the earth's axis, gradually slowing down the rotation of our planet.
- repeatedly caused the extinction of various types of 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 taking place 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 have attracted 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 perfect, in contrast to the earthly, flattened one.
- Since the sun cannot be seen because of the constant clouds. Also, there is no change of seasons as such.
- Scientists suggest that Venus previously had large reserves of water, but it has long since evaporated as a result of increased solar radiation.
- Life on Venus is impossible due to the very high temperature.
- A day on the planet lasts a little less than an earthly year!
Mercury
Consider 2-3 more interesting facts about the terrestrial planets.
- Mercury is the smallest (according to data for 2006, when Pluto lost its planetary status) and the closest planet to our main luminary in the solar system.
- This body is the least studied. So, scientists only in 2009 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, a satellite of Mars, rises and sets twice a day.
- When Mars comes close to Earth, the largest number of UFO sightings is recorded.
This is how the terrestrial planets can be described. All the facts about space, provided by scientists, have recently aroused great interest among the general public. This is connected 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.