Space has attracted people's attention for a long time. planets solar system astronomers began to study in the Middle Ages, looking at them through primitive telescopes. But a thorough classification, description of the features of the structure and movement of celestial bodies became possible only in the 20th century. With the advent of powerful equipment, state-of-the-art observatories and spacecraft, several previously unknown objects have been discovered. Now each student can list all the planets of the solar system in order. Almost all of them have been landed by a space probe, and so far man has only been to the Moon.
What is the solar system
The universe is huge and includes many galaxies. Our solar system is part of a galaxy with over 100 billion stars. But there are very few that look 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. Its huge field of attraction captured a gas-dust cloud, from which, as a result of gradual cooling, particles of solid matter were formed. Over time, celestial bodies formed from them. It is believed that the Sun is now in the middle of its life path, therefore, it will exist, as well as all celestial bodies dependent on it, for several billion more 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 from space satellites, can be found on the pages of various information resources dedicated to this topic. All celestial bodies are held by the Sun's strong gravitational field, which makes up over 99% of the solar system's volume. Large celestial bodies revolve around the star and around their axis in one direction and in one plane, which is called the plane of the ecliptic.
Solar system planets in order
In modern astronomy, it is customary to consider celestial bodies, starting from the Sun. In the 20th century, a classification was created, which includes 9 planets of the solar system. But recent space exploration and the latest discoveries have prompted scientists to revise many positions in astronomy. And in 2006, at the 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 four terrestrial planets: Mercury, Venus, Earth and Mars, then comes the asteroid belt, followed by four giant planets: Jupiter, Saturn, Uranus and Neptune. On the outskirts of the solar system also passes which scientists called the Kuiper belt. This is where Pluto is located. These places are still little studied because of their remoteness from the Sun.
Features of the terrestrial planets
What makes it possible to attribute these celestial bodies to one group? We list the main characteristics of the inner planets:
- relatively small size;
- hard surface, high density and similar composition (oxygen, silicon, aluminum, iron, magnesium and other heavy elements);
- the presence of an atmosphere;
- the same 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 size and weight;
- they do not have a solid surface and are composed of gases, mainly helium and hydrogen (which is why they are also called gas giants);
- a 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 of gas giants is 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 luminary looks three times larger than from the Earth. This also explains the strong temperature fluctuations: from -180 to +430 degrees. Mercury is moving very fast in its orbit. Maybe that's why he got such a name, because in Greek mythology, Mercury is the messenger of the gods. There is almost 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 axis of rotation. No water was found on the surface. This circumstance, as well as the anomalously high daytime temperature (as well as the low nighttime temperature) fully explain the fact that there is no life on the planet.
Venus
If we study the planets of the solar system in order, then the second one is Venus. People could observe her in the sky in ancient times, but since she was shown only in the morning and in the evening, it was believed that these were 2 different objects. By the way, our Slavic ancestors called her Flicker. It is the third brightest object in our solar system. Formerly people they called it the morning and evening star, because it is best seen before sunrise and sunset. Venus and Earth are very similar in structure, composition, size and gravity. Around its axis, this planet moves very slowly, making a complete revolution in 243.02 Earth days. Of course, the conditions on Venus are very different from those on Earth. It is twice as close to the Sun, so it is very hot there. The high temperature 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 survived there for no more than an hour. A feature of the planet is also the fact that it rotates in the opposite direction, compared to most planets. Astronomers know nothing more about this celestial object yet.
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 the Earth. In the terrestrial group, it has the largest dimensions. What else is her
- The largest gravity among the terrestrial planets.
- Very strong magnetic field.
- High density.
- It is the only one among all the planets that has a hydrosphere, which contributed to the formation of life.
- It has the largest, in comparison with its size, satellite, which stabilizes its tilt relative to the Sun and affects natural processes.
The planet Mars
It 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 drops are observed. The planet Mars is 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. Such a conclusion can be drawn from the fact that there are large ice caps at the poles, and the surface is covered with many furrows, 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. Their unusualness 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. 1300 Earths would fit in the volume of Jupiter, and its mass is 317 times more than the 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 all the planets;
- it completes a full rotation around its axis in just 10 earth hours - faster than other planets;
- an interesting feature of Jupiter is a large red spot - this is how an atmospheric vortex is visible from the Earth, rotating counterclockwise;
- like all giant planets, it has rings, though not as bright as those of Saturn;
- this planet has the largest a large number of satellites. He has 63 of them. The most famous are Europa, where they found water, Ganymede - the largest satellite of the planet Jupiter, as well as Io and Calisto;
- another feature of the planet is that in the shade the surface temperature is higher than in places illuminated by the Sun.
Planet Saturn
This is the second largest gas giant, also named after the ancient god. It consists of hydrogen and helium, but traces of methane, ammonia and water have been found on its surface. Scientists have found that Saturn is the most rarefied planet. Its density is less than that of water. This gas giant rotates very quickly - it completes one revolution in 10 Earth hours, as a result of which the planet is flattened from the sides. Huge speeds on Saturn and near the wind - up to 2000 kilometers per hour. It's more than the speed of sound. Saturn has another 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, exploring its surface, scientists first 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 encircle the planet around the equator and reflect more light than itself. Four is the most amazing phenomenon in the solar system. Unusually, the inner rings move faster than the outer ones.
- 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. Because Uranus is classified as a separate category of ice giants. An 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: winter reigns there for 42 Earth years, 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 luminary 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 holds 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, in 19 times greater than the path to the luminary 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 farther from the star than the Earth, and is not visible from our planet even through 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, interesting features of this planet were revealed:
- 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 completes one circle in 165 years;
- Neptune is 4 times larger than the Earth and 17 times heavier, but the force of attraction is almost the same as on our planet;
- the largest of the 13 moons of this giant is Triton. It is always turned to the planet on one side and slowly approaches it. Based on these signs, scientists have suggested that it was captured by Neptune's gravity.
In the entire galaxy, the Milky Way is about a hundred billion planets. So far, scientists cannot even study 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 name of the planets of the solar system.
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 about 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 description.
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, are composed mainly of hydrogen and helium; smaller gas giants, Uranus and Neptune, in addition to hydrogen and helium, contain methane and carbon monoxide in their atmospheres.
Rice. 1. Planets of the solar system.
The list of planets in the solar system in order from the sun is as follows: 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 revolve around the Sun in the same direction as the Sun's rotation (counterclockwise as viewed from the north pole of the Sun).
Mercury has the highest angular velocity - it manages to make a complete revolution around the Sun in just 88 Earth days. And for the most distant planet - Neptune - the period of revolution 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, and Uranus rotates almost "lying on its side" (axis tilt is about 90 degrees).
TOP 2 articleswho read along with this
Table. The sequence of the planets in the solar system and their features.
|
Planet |
Distance from the Sun |
Period of circulation |
Rotation period |
Diameter, km. |
Number of satellites |
Density g / cu. cm. |
|
Mercury |
||||||
Terrestrial planets (inner planets)
The four planets closest to the Sun consist mainly of heavy elements, have a small number of satellites, and have no rings. They are largely composed of refractory minerals such as silicates that form their mantle and crust, and metals such as iron and nickel that form their core. Three of these planets - Venus, Earth and Mars - have an atmosphere.
- 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 the iron core and 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, with surface temperatures exceeding 400 degrees Celsius. The most likely reason for such a high temperature is the greenhouse effect due to the dense atmosphere rich in carbon dioxide.
Rice. 2. Venus is the hottest planet in the solar system
- Earth- is the largest and densest 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 the hydrosphere). 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 planets of the terrestrial group of the solar system.
- Mars – smaller than Earth and Venus. It has an atmosphere composed mainly of carbon dioxide. On its surface there are volcanoes, the largest of which, Olympus, exceeds the size of all terrestrial volcanoes, reaching a height of 21.2 km.
Outer region of the solar system
The outer region of the solar system is the location of the gas giants and their satellites.
- Jupiter- has a mass of 318 times more than the earth, and 2.5 times more massive than all the 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 moons.
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 axis of rotation to the plane of the ecliptic is approximately 98 degrees. Uranus has 27 moons.
- Neptune is 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 of astronomy is the structure of the solar system. We learned what names of the planets of the solar system are, in what order they are located in relation to the Sun, what are their distinctive features and brief characteristics. This information is so interesting and informative that it will be useful even for children in grade 4.
Topic quiz
Report Evaluation
Average rating: 4.5. Total ratings received: 886.
Questions:1. How is the name "wandering stars" translated from Greek?
2. Name the inner planets.
3. What planets are outer?
Planet - a solid body or a solid body and gas that revolve around a star.Even the ancient people in the sky noticed constantly moving stars, and the Greeks called them that "wandering stars" which is Greek for planets.
There are nine planets in the solar system: Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, Jupiter, Pluto.
inner planets- Mercury, Mars, Venus, Earth.
The planets belonging to this group are small in size and mass, the average density of these planets is several times greater than the density of water; they slowly rotate around their axes; they have few satellites Mercury and Venus they don't exist at all Mars- two, at Earth- one).
The similarity of the terrestrial planets does not exclude some differences. For example, Venus, unlike other planets, rotates in the opposite direction to its movement around the Sun, and 243 times slower than the Earth.
Period of circulation Mercury(i.e., the year of this planet) is only 1/3 more than the period of its rotation around the axis.
The angles of inclination of the axes to the planes of their orbits y Earth and at Mars roughly the same, but very different Mercury and Venus. Same as those earth, seasons are on mars, although almost twice as long as Earth.
Similarities and differences are also found in the atmospheres of the terrestrial planets. Unlike Mercury, which, like Moon, almost devoid of atmosphere Venus and Mars possess it.
Venus It has a very dense atmosphere, mainly composed of carbon dioxide and sulfur compounds. Atmosphere Mars on the contrary, it is extremely rarefied and also poor in oxygen and nitrogen. Surface pressure Venus almost 100 times more than Mars almost 150 times smaller than at the surface Earth.
outer planets include Neptune, Uranus, Saturn, Jupiter, Pluto.
GIANT PLANETS Jupiter, Saturn, Uranus and Neptune completely does not correspond to our ideas about comfort: very cold, terrible gas composition (methane, ammonia, hydrogen, etc.), there is practically no solid surface - only a dense atmosphere and an ocean of liquid gases. All this is very different from Earth. However, in the era of the origin of life, the Earth was not at all the same as it is now. Its atmosphere was more like that of Venus and Jupiter, except that it was warmer. Therefore, a search for organic compounds in the atmosphere of giant planets will certainly be carried out in the near future.
The giant planets are far from the Sun, and regardless of the nature of the change of seasons, they are always dominated by low temperatures. On the Jupiter there is no change of seasons at all, since the axis of this planet is almost perpendicular to the plane of its orbit. There is a peculiar change of seasons and on the planet Uranus, since the axis of this planet is inclined to the plane of the orbit at an angle of 8¦.
The giant planets are distinguished by a large number of satellites; Jupiter has 16 of them so far, Saturn - 17, uranium- 16 and y Neptune - 8. Interesting feature the giant planets have - these are rings that were found not only in Saturn, but also Jupiter, Uranus and Neptune.
The most important feature of the structure of the giant planets is that these planets have a solid surface. They consist mainly of light elements - hydrogen and helium.
Orbits The planets are elliptical with the Sun at one of the foci, although all except the orbits of Mercury and Pluto are nearly circular. All planetary orbits are more or less in the same plane (called ecliptic and determined by the plane of the Earth's orbit). The plane of the ecliptic is only 7 degrees off the plane of the Sun's equator. Pluto's orbit deviates the most from the plane of the ecliptic (by 17 degrees). The diagram above shows the relative sizes of the orbits of the nine planets when viewed from above on the ecliptic (hence they are not round). They all rotate in the same direction (clockwise when looking down from the Sun's north pole; all but Venus, Uranus and Pluto rotate around their axis in the same direction.
The image above shows nine planets with approximately correct relative dimensions(see other similar images and comparison of terrestrial planets or Appendix 2 for more details).
One way to imagine actual dimensions The solar system is to imagine a model in which all dimensions and distances are reduced by a billion times (1e9). Then the Earth will be about 1.3 cm in diameter (the size of a grape). The moon rotates at a distance of ~30 cm from it. The sun in this case would be 1.5 meters in diameter (about the height of a person) and located at a distance of 150 meters (about a city block) from the Earth. Jupiter is 15 cm in diameter (the size of a large grapefruit) and 5 city blocks from the Sun. Saturn - (the size of an orange) at a distance of 10 blocks; Uranus and Neptune (lemons) - 20 and 30 quarters. A person on this scale would be the size of an atom; and the nearest star is 40,000 km away.
Numerous small bodies that are in the solar system are not shown in the upper illustration: satellites of planets; big number asteroids (small rocky bodies) orbiting the Sun, mostly between Mars and Jupiter, but also elsewhere; and comets (small icy bodies) that come and go from the inner solar system in highly elevated orbits and random orientations to the ecliptic. With a few exceptions, the satellites of planets rotate in the same way as their planets and are approximately in the plane of the ecliptic, but this is not always the case for comets and asteroids.
Classification
The classification of these bodies is the subject of much debate.. Traditionally, the solar system was divided into planets(large bodies revolving around the sun), their satellites(or moons, objects of various sizes orbiting planets), asteroids(objects with low density revolving around the Sun) and comets(small icy bodies with highly eccentric orbits). Unfortunately, the solar system turned out to be more complex than expected:- there are several moons larger than Pluto and two larger than Mercury;
- there are several small satellites that are probably captured asteroids;
- comets sometimes fizzle out and become indistinguishable from asteroids;
- objects from the Kuiper Belt and others like Chiron do not fit this pattern so well;
- The Earth/Moon and Pluto/Charon systems are sometimes referred to as "double planets".
The nine bodies traditionally referred to as planets are often further classified as follows:
- by composition:
- earthly or rocky planets: Mercury, Venus, Earth, and Mars:
- The terrestrial planets consist mainly of stone and metal and have relatively high densities, do not rotate strongly, have a solid surface, do not have rings, and the number of satellites is small.
- giant planetsor gas planets: Jupiter, Saturn, Uranus, and Neptune:
- Gas planets are composed primarily of hydrogen and helium and typically have low densities, rotate rapidly, have deep atmospheres, rings, and a large number of satellites.
- Pluto.
- earthly or rocky planets: Mercury, Venus, Earth, and Mars:
- to size:
- small planets: Mercury, Venus, Earth, Mars and Pluto.
- Small planets are less than 13,000 km in diameter.
- giant planets: Jupiter, Saturn, Uranus, Neptune.
- The diameter of these planets is greater than 48,000 km.
- Mercury and Pluto are sometimes represented as least planets (do not confuse with small planets, is the official term for asteroids).
- Giant planets are sometimes also classified as gas giants.
- small planets: Mercury, Venus, Earth, Mars and Pluto.
- by location relative to the sun:
- internal solar system planets: Mercury, Venus, Earth and Mars.
- external planets of the solar system: Jupiter, Saturn, Uranus, Neptune and Pluto.
- The asteroid belt between Mars and Jupiter is the boundary between the inner and outer solar system.
- by location relative to Earth :
- internal planets: Mercury and Venus.
- closer to the sun than the earth.
- These planets, when viewed from Earth, have phases similar to those of the moon.
- Earth.
- external planets: from Mars to Pluto.
- farther from the Sun than Earth.
- These planets always seem to be full or so.
- internal planets: Mercury and Venus.
- by history:
- classical planets: Mercury, Venus, Mars, Jupiter, Saturn.
- known since prehistoric times
- visible to the naked eye
- modern planets: Uranus, Neptune, Pluto.
- are currently open
- only visible through a telescope
- Earth.
- classical planets: Mercury, Venus, Mars, Jupiter, Saturn.
Pictures
Comment: most of the images in Nine Planets do not convey the exact color of the object. Most of them were created by combining several black and white images taken through various color filters. While the colors look "real" enough, they're not exactly what you see them.- Montage of Nine Planets (large version on top) 36k jpg
- Another size comparison (from LANL) 93k gif
- Sun and major planets, comparison (from Extrema) 41k gif
- Earth and small bodies, comparison (from Extrema) 35k gif
- Voyager 1 solar system mosaic from 4 billion miles away 36k jpg ; 85k gif (caption)
- Voyager 1 image of 6 planets from 4 billion miles away 123k jpg ; 483k gif
- Pale Blue Dot, a reflection of the above images by Carl Sagan.
More general overview
- History of the discovery of the solar system
- Solar system. Introduction from LANL
- Solar System Family Portrait from NSSDC
- The Life of the Solar System, interactive information from the web.
- Our solar system from NASA Spacelink
- Notes on Far Distant Solar System Objects (from RGO)
- planetary surface temperature notes (from RGO)
- scaled models of the solar system
- Scaled Model of the Solar System Meta Page (links to others)
- Lakeview Museum Community Solar System, the world's largest scaled model of the Solar System from LPI
- Sagan Planet Walk in Ithaca, NY
- Construction of the Solar System, computation of scaled models
- Silver City, NM
- Solar System Walk in Gainesville, Florida
- PlanetTrek, a scaled model of the solar system
- Walking the Solar System, a visual size calculation for comparison from the Exploratorium
