In ancient times, people knew only five planets: Mercury, Venus, Mars, Jupiter and Saturn, the only ones that can be seen with the naked eye.
Uranus, Neptune and Pluto were discovered using telescopes in 1781, 1846 and 1930. For a long time, astronomers studied the planets by observing them from Earth. They determined that all the planets, except Pluto, move in circular orbits in the same plane and in the same direction, calculated the sizes of the planets and the distances from them to the Sun, formed their idea of the structure of the planets, and even assumed that Venus and Mars could be similar Earth, and there may be life on them.
The launch of automatic space stations to the planets made it possible to significantly expand, and in many ways revise, ideas about the planets: it became possible to see photographs of the surface, explore the soil and atmosphere of the planets.
Mercury.
Mercury is a small planet, slightly larger than the Moon. Its surface is also dotted with craters from collisions with meteorites. No geological processes have erased these dents from his face. Mercury is cold inside. It moves around the Sun faster than other planets, but around its axis very slowly. Having circled the Sun twice, Mercury only has time to turn around its axis three times. Because of this, the temperature on the sunny side of the planet exceeds 300 degrees, and on the unlit side there is darkness and severe cold. Mercury has virtually no atmosphere.
Venus.
Exploring Venus is not easy. It is shrouded in a thick layer of clouds, and under this serene exterior lies a real hell, the pressure is a hundred times higher than on Earth, the temperature on the surface is about 500 degrees, which is caused by the “greenhouse effect”. The Soviet automatic station “Venera - 9” for the first time managed to transmit to Earth images of a surface filled with lava and covered with stones. In the conditions of Venus, the apparatus lowered to the surface of the planet quickly breaks down, so American scientists decided to obtain data on the planet’s topography in a different way.
The Magellan robotic probe, having flown around Venus many times, probed the planet with radar, resulting in a comprehensive picture of the surface. In some places, the relief of Venus is similar to that of Earth, but mostly the landscapes are strange: high mountainous round areas surrounded by mountain ranges 250 - 300 km in diameter, the entire area of which is occupied by volcanoes; other volcanic formations resemble cakes with steep edges and a flat top. The surface of the planet is cut by channels laid by lava. Traces of active volcanic activity are visible everywhere. Meteor craters on the surface of Venus are distributed evenly, which means that its surface took shape at the same time. Scientists cannot explain how this could happen; Venus seemed to boil and be flooded with lava. Now volcanic activity is not detected on the planet.
The atmosphere of Venus is not at all similar to that of Earth; it mainly consists of carbon dioxide. The thickness of the gas shell of Venus, compared to the earth's, is monstrously large. The cloud layer reaches 20 km. The presence of a concentrated aqueous solution of sulfuric acid was detected in them. Sunlight does not reach the surface of Venus, twilight reigns there, sulfur rain falls, and the landscape is constantly illuminated by flashes of lightning. High in the planet's atmosphere, constant winds rage, driving clouds at tremendous speed; the upper layer of the Venusian atmosphere makes a complete revolution around the planet within four Earth days. The solid body of Venus, on the contrary, rotates around its axis very slowly and in a different direction than all the other planets. Venus has no satellites.
Mars.
In the 20th century, the planet Mars was chosen by science fiction writers; in their novels, the Martian civilization was incomparably higher than the earthly one. The mysterious, inaccessible Mars began to reveal its secrets when Soviet and American automatic spacecraft began to be sent to study it.
The Mariner 9 station, orbiting Mars, took photographs of all areas of the planet, which made it possible to create a detailed map of the surface relief. Researchers have discovered traces of active geological processes on the planet: huge volcanoes, the largest of them, Olympus Mons, 25 km high, and a huge fault in the Martian crust, called Valles Marineris, which crosses an eighth of the planet.
Gigantic structures grew in the same place for billions of years, unlike the Earth with its drifting continents, the surface of Mars did not move. The geological structures of the Earth, compared to those on Mars, are dwarfs. Are volcanoes active on Mars now? Scientists believe that geological activity on the planet is obviously a thing of the past.
Martian landscapes are dominated by reddish rocky deserts. Light transparent clouds float above them in the pink sky. The sky turns blue at sunset. The atmosphere of Mars is very thin. Every few years there are dust storms that cover almost the entire surface of the planet. A day on Mars lasts 24 hours 37 minutes, the inclination of the axis of rotation of Mars to the orbital plane is almost the same as that of the Earth, so the change of seasons on Mars is quite consistent with the change of seasons on Earth. The planet is poorly heated by the Sun, so its surface temperature even on a summer day does not exceed 0 degrees, and in winter, frozen carbon dioxide settles on the rocks due to the severe cold, and the Polar Caps are mainly made of it. No traces of life have yet been found.
From Earth, Mars is visible as a reddish star, which is probably why it bears the name of the god of war, Mars. His two companions were named Phobos and Deimos, which translated from ancient Greek means “fear” and “horror.” The satellites of Mars are space “rocks” of irregular shape. Phobos measures 18km x 22km, and Deimos measures 10km x 16km.
The planets are giants.
In 1977, American scientists and engineers launched an automatic interplanetary station towards Jupiter as part of the Voyager program. Once every 175 years, Jupiter, Saturn, Neptune and Pluto are positioned in such a way relative to the Earth that a launched spacecraft can examine all these planets in one flight. Scientists have calculated that, under certain conditions, a spacecraft, approaching a planet, falls into a gravitational slingshot, and the planet itself sends the apparatus further to another planet. The calculations turned out to be correct. Earthlings were able to see these distant planets and their satellites through the “eyes” of space robots, and unique information was transmitted to Earth.
Jupiter.
Jupiter is the largest planet in the solar system. It does not have a solid surface and consists mainly of hydrogen and helium. Due to the high speed of rotation around its axis, it is noticeably compressed at the poles. Jupiter has a huge magnetic field; if it became visible, it would look the size of the solar disk from Earth.
In the photographs, scientists were able to see only clouds in the planet’s atmosphere, which create stripes parallel to the equator. But they moved with great speed, bizarrely changing their shape. Numerous vortices, auroras and lightning flashes were recorded in the cloud cover of Jupiter. On the planet, wind speeds reach one hundred kilometers per hour. The most amazing formation in the atmosphere of Jupiter is a large red spot 3 times the size of the Earth. Astronomers have observed it since the 17th century. It is possible that this is the tip of a gigantic tornado. Jupiter releases more energy than it receives from the Sun. Scientists believe that in the center of the planet, gases are compressed to the state of a metallic liquid. This hot core is the power plant that generates winds and a monstrous magnetic field.
But the main surprises for scientists were not presented by Jupiter itself, but by its satellites.
Satellites of Jupiter.
There are 16 known satellites of Jupiter. The largest of them, Io, Europa, Callisto and Ganymede, were discovered by Galileo; they are visible even with strong binoculars. It was believed that the satellites of all planets are similar to the Moon - they are cold and lifeless. But Jupiter's moons surprised researchers.
And about- the size of the Moon, but it is the first celestial body other than Earth on which active volcanoes have been discovered. Io is completely covered in volcanoes. Its surface is washed by multi-colored lava flows, volcanoes emit sulfur. But what is the reason for the active volcanic activity of such a small cosmic body? Revolving around the huge Jupiter, Io either approaches it or moves away.
Under the influence of either increasing or decreasing gravitational force, Io either contracts or expands. Friction forces heated its inner layers to enormous temperatures. Io's volcanic activity is incredible, its surface changing before our eyes. Io moves in Jupiter's powerful magnetic field, so it accumulates a huge electrical charge, which is discharged onto Jupiter in the form of a continuous stream of lightning, causing storms on the planet.
Europe has a relatively smooth surface, virtually without relief. It is covered with a layer of ice, and it is likely that the ocean is hidden underneath it. Instead of molten rocks, water oozes from cracks here. This is a completely new type of geological activity.
Ganymede- the largest satellite in the solar system. Its size is almost the same as that of Mercury.
Callisto dark and cold, its surface, pockmarked with meteorite craters, has not changed for billions of years.
Saturn.
Saturn, like Jupiter, does not have a solid surface - it is a gas giant planet. It also consists of hydrogen and helium, but it is cooler, since it produces less heat itself and receives less of it from the Sun. But on Saturn the winds are faster than on Jupiter. Stripes, vortices and other formations are observed in the atmosphere of Saturn, but they are short-lived and irregular.
Naturally, scientists' attention was directed to the rings that surround the planet's equator. They were discovered by astronomers back in the 17th century, and since then scientists have been trying to understand what they are. Photos of the rings transmitted to earth by an automatic space station surprised researchers. They were able to identify several hundred rings nested inside one another, some intertwined with each other, dark stripes were found on the rings that appeared and disappeared, they were called knitting needles. Scientists were able to see the rings of Saturn from a fairly close distance, but they had more questions than answers.
In addition to the rings, 15 satellites move around Saturn. The largest of them is Titan, slightly smaller than Mercury. Titan's dense atmosphere is much thicker than Earth's and consists almost entirely of nitrogen; it did not allow us to see the surface of the satellite, but scientists suggest that the internal structure of Titan is similar to the structure of the Earth. The temperature at its surface is below minus 200 degrees.
Uranus.
Uranus differs from all other planets in that its axis of rotation lies almost in the plane of its orbit, all planets look like a toy top, and Uranus rotates as if “lying on its side.” Voyager was able to “see” little in the atmosphere of Uranus; the planet turned out to be very monotonous in appearance. There are 5 satellites orbiting Uranus.
Neptune.
It took Voyager 12 years to get to Neptune. How surprised the scientists were when, on the outskirts of the solar system, they saw a planet very similar to Earth. It was a deep blue color, with white clouds moving in different directions in the atmosphere. The winds on Neptune blow much stronger than on other planets.
There is so little energy on Neptune that the wind, once it picks up, cannot stop. Scientists have discovered a system of rings around Neptune, but they are incomplete and represent arcs; there is no explanation for this yet. Neptune and Uranus are also giant planets, but not gas, but ice.
Neptune has 3 satellites. One of them is that Triton rotates in the direction opposite to the direction of rotation of Neptune itself. Perhaps it did not form in Neptune's gravitational zone, but was pulled toward the planet when it came close to it and fell into its gravitational zone. Triton is the coldest body in the solar system, its surface temperature is slightly above absolute zero (minus 273 degrees). But nitrogen geysers were discovered on Triton, which indicates its geological activity.
Pluto
Now Pluto is officially no longer a planet. It should now be considered a "dwarf planet", one of three in the Solar System. Pluto's fate was determined in 2006 by a vote of members of the International Astronomical Society in Prague.
To avoid confusion and not clutter maps of the Solar System, the International Astronomical Union has prescribed that fairly large celestial bodies that are not among the eight previously defined planets be classified as dwarf planets. In particular, Pluto, Charon (a former satellite of Pluto), the asteroid Ceres, orbiting between the orbits of Mars and Jupiter, as well as the so-called Kuiper belt objects Xena (object UB313) and Sedna (object 90377) received a new status.
The sun holds the planets and other bodies belonging to the solar system with its gravity.
Other bodies are planets and their satellites, dwarf planets and their satellites, asteroids, meteoroids, comets and cosmic dust. But in this article we will only talk about the planets of the solar system. They make up most of the mass of objects associated with the Sun by gravity (attraction). There are only eight of them: Mercury, Venus, Earth Mars, Jupiter, Saturn, Uranus and Neptune . The planets are named in order of their distance from the Sun. Until recently, the planets of the solar system also included Pluto, the smallest planet, but in 2006 Pluto was deprived of planet status because Many objects more massive than Pluto have been discovered in the outer solar system. Following the reclassification, Pluto was added to the list of minor planets and received catalog number 134340 from the Minor Planet Center. But some scientists disagree with this and continue to believe that Pluto should be reclassified back to a planet.
Four planets - Mercury, Venus, Earth and Mars - are called terrestrial planets. They are also called inner planets, because their orbits lie inside the Earth's orbit. What the terrestrial planets have in common is that they consist of silicates (minerals) and metals.
Four other planets - Jupiter, Saturn, Uranus and Neptune - they call gas giants, because they are mainly composed of hydrogen and helium and are much more massive than the terrestrial planets. They are also called outer planets.
Look at the picture of the terrestrial planets scaled by their sizes in relation to each other: Earth and Venus are about the same size, and Mercury is the smallest planet among the terrestrial planets (from left to right: Mercury, Venus, Earth, Mars).
What unites the terrestrial planets, as we have already said, is their composition, as well as the fact that they have a small number of satellites and that they do not have rings. The three inner planets (Venus, Earth and Mars) have an atmosphere (a shell of gas around a celestial body held in place by gravity); all have impact craters, rift basins and volcanoes.
Let us now consider each of the terrestrial planets.
Mercury
It is located closest to the Sun and is the smallest planet in the solar system, its mass is 3.3 × 10 23 kg, which is 0.055 the mass of the Earth. The radius of Mercury is only 2439.7 ± 1.0 km. The average density of Mercury is quite high - 5.43 g/cm³, which is slightly less than the density of Earth. Considering that the Earth is larger in size, the density value of Mercury indicates an increased content of metals in its depths.
The planet got its name in honor of the ancient Roman god of trade, Mercury: he was fleet-footed, and the planet moves across the sky faster than other planets. Mercury has no satellites. Its only known geological features, other than impact craters, are numerous jagged escarpments extending for hundreds of kilometers. Mercury has an extremely thin atmosphere, a relatively large iron core and a thin crust, the origin of which is currently a mystery. Although there is a hypothesis: the outer layers of the planet, consisting of light elements, were torn off as a result of a giant collision, which reduced the size of the planet and also prevented the complete absorption of Mercury by the young Sun. The hypothesis is very interesting, but requires confirmation.
Mercury revolves around the Sun in 88 Earth days.
Mercury has not yet been sufficiently studied; only in 2009 was its complete map compiled based on images from the Mariner 10 and Messenger spacecraft. The planet’s natural satellites have not yet been discovered, and it is not easy to see in the sky due to its small angular distance from the Sun.
Venus
It is the second inner planet of the solar system. It orbits the Sun in 224.7 Earth days. The planet is close in size to Earth, its mass is 4.8685ˑ10 24 kg, which is 0.815 Earth's mass. Like Earth, it has a thick silicate shell around an iron core and an atmosphere. Venus is the third brightest object in the Earth's sky after the Sun and Moon. It is believed that internal geological activity occurs within the planet. The amount of water on Venus is much less than on Earth, and its atmosphere is ninety times denser. Venus has no satellites. This is the hottest planet, its surface temperature exceeds 400 °C. Astronomers consider the most likely reason for such a high temperature to be the greenhouse effect, which occurs due to a dense atmosphere rich in carbon dioxide, which is approximately 96.5%. The atmosphere on Venus was discovered by M. V. Lomonosov in 1761.
There is no evidence of geological activity on Venus, but since it has no magnetic field to prevent the depletion of its substantial atmosphere, it is assumed that its atmosphere is regularly replenished by volcanic eruptions. Venus is sometimes called " sister of the earth“- they really have a lot in common: similar sizes, gravity and composition. But there are still more differences. The surface of Venus is covered by a thick cloud of highly reflective sulfuric acid clouds, making its surface impossible to see in visible light. But radio waves were able to penetrate its atmosphere, and with their help its relief was explored. Scientists have debated for a long time about what lies under the thick clouds of Venus. And only in the 20th century, the science of planetology established that the atmosphere of Venus, consisting mainly of carbon dioxide, is explained by the fact that on Venus there is no carbon cycle and no life that could process it into biomass. Scientists believe that once upon a time, a very long time ago, oceans similar to those on Earth existed on Venus, but they completely evaporated due to the intense heating of the planet.
The atmospheric pressure on the surface of Venus is 92 times greater than on Earth. Some astronomers believe that volcanic activity on Venus continues today, but no clear evidence of this has been found. Not found yet... It is believed that Venus is a relatively young planet, by astronomical standards, of course. She is approximately only... 500 million years old.
The temperature on Venus has been calculated to be approximately +477 °C, but scientists believe that Venus is gradually losing its internal high temperature. Observations from automatic space stations have detected thunderstorms in the planet's atmosphere.
The planet got its name in honor of the ancient Roman goddess of love Venus.
Venus has been actively studied using spacecraft. The first spacecraft was the Soviet Venera 1. Then there were the Soviet Vega, the American Mariner, Pioneer Venus 1, Pioneer Venus 2, Magellan, the European Venus Express, and the Japanese Akatsuki. In 1975, the Venera 9 and Venera 10 spacecraft transmitted the first photographs of the surface of Venus to Earth, but conditions on the surface of Venus are such that none of the spacecraft worked on the planet for more than two hours. But research on Venus continues.
Earth
Our Earth is the largest and densest of the inner planets in the solar system. Among the terrestrial planets, the Earth is unique due to its hydrosphere (water shell). The Earth's atmosphere differs from the atmospheres of other planets in that it contains free oxygen. The Earth has one natural satellite - the Moon, the only large satellite of the terrestrial planets of the Solar System.
But we will have a more detailed conversation about planet Earth in a separate article. Therefore, we will continue the story about the planets of the solar system.
Mars
This planet is smaller than Earth and Venus, its mass is 0.64185·10 24 kg, which is 10.7% of the Earth's mass. Mars is also called " red planet" - due to iron oxide on its surface. Its rarefied atmosphere consists mainly of carbon dioxide (95.32%, the rest is nitrogen, argon, oxygen, carbon monoxide, water vapor, nitrogen oxide), and the pressure on the surface is 160 times less than that on Earth. Impact craters like those on the Moon, as well as volcanoes, valleys, deserts and polar ice caps like those on Earth - all this makes it possible to classify Mars as a terrestrial planet.
The planet got its name in honor of Mars, the ancient Roman god of war (which corresponds to the ancient Greek Ares). Mars has two natural, relatively small satellites - Phobos and Deimos (translated from ancient Greek - “fear” and “horror” - that was the name of the two sons of Ares, who accompanied him in battle).
Mars was studied by the USSR, the USA and the European Space Agency (ESA). The USSR/Russia, USA, ESA and Japan sent an Automatic Interplanetary Station (AIS) to Mars to study it; there were several programs to study this planet: “Mars”, “Phobos”, “Mariner”, “Viking”, “Mars Global Surveyor” and others.
It has been established that due to low pressure, water cannot exist in a liquid state on the surface of Mars, but scientists suggest that in the past conditions on the planet were different, so they do not exclude the presence of primitive life on the planet. In 2008, water in the form of ice was discovered on Mars by NASA's Phoenix spacecraft. The surface of Mars is explored by rovers. The geological data they collected suggests that most of the surface of Mars was once covered with water. On Mars, they even discovered something like geysers - sources of hot water and steam.
Mars can be seen from Earth with the naked eye.
The minimum distance from Mars to the Earth is 55.76 million km (when the Earth is exactly between the Sun and Mars), the maximum is about 401 million km (when the Sun is exactly between the Earth and Mars).
The average temperature on Mars is −50 °C. The climate, like on Earth, is seasonal.
Asteroid belt
Between Mars and Jupiter there is a belt of asteroids - small bodies of the solar system. Scientists suggest that these are remnants of the formation of the Solar System, which were unable to unite into a large body due to gravitational disturbances of Jupiter. The sizes of asteroids vary: from several meters to hundreds of kilometers.
Outer Solar System
In the outer region of the Solar System there are gas giants ( Jupiter, Saturn, Uranus and Neptune ) and their companions. The orbits of many short-period comets are also located here. Because of their greater distance from the Sun, and therefore much lower temperature, the solid objects in this region contain ices of water, ammonia and methane. In the photo you can compare their sizes (from left to right: Jupiter, Saturn, Uranus, Neptune).
Jupiter
This is a huge planet with a mass of 318 Earth masses, which is 2.5 times more massive than all other planets combined, and its equatorial radius is 71,492 ± 4 km. It consists mainly of hydrogen and helium. Jupiter is the most powerful (after the Sun) radio source in the Solar System. The average distance between Jupiter and the Sun is 778.57 million km. The presence of life on Jupiter seems unlikely due to the low concentration of water in the atmosphere, the absence of a solid surface, etc. Although scientists do not exclude the possibility of the existence of water-hydrocarbon life on Jupiter in the form of some unidentified organisms.
Jupiter has been known to people since ancient times, which is reflected in the mythology of different countries, and its name comes from the ancient Roman thunder god Jupiter.
There are 67 known moons of Jupiter, the largest of which were discovered by Galileo Galilei in 1610.
Jupiter is explored using ground-based and orbital telescopes; Since the 1970s, 8 interplanetary NASA probes have been sent to the planet: Pioneers, Voyagers, Galileo and others. Powerful storms, lightning, and aurorae, many times greater than those on Earth, have been observed on the planet.
Saturn
A planet known for its ring system. In reality, these romantic rings are just flat, concentric formations of ice and dust that lie in Saturn's equatorial plane. Saturn has a structure of atmosphere and magnetosphere somewhat similar to Jupiter, but is much smaller: 60% of the mass of Jupiter (5.6846 10 26 kg). Equatorial radius - 60,268 ± 4 km.
The planet received its name in honor of the Roman god of agriculture, Saturn, so its symbol is a sickle.
The main component of Saturn is hydrogen with admixtures of helium and traces of water, methane, ammonia and heavy elements.
Saturn has 62 satellites. Of these, the largest is Titan. It is interesting because it is larger than the planet Mercury and has the only dense atmosphere among the satellites of the Solar System.
Observations of Saturn have been going on for a long time: Galileo Galilei noted in 1610 that Saturn has “two companions” (satellites). And Huygens in 1659, using a more powerful telescope, saw the rings of Saturn and discovered its largest satellite, Titan. Then, gradually, astronomers discovered other satellites of the planet.
The modern study of Saturn began in 1979, when the US automatic interplanetary station Pioneer 11 flew near Saturn and then finally approached it. Then the American spacecraft Voyager 1 and Voyager 2, as well as Cassini-Huygens, followed to Saturn, which, after 7 years of flight, reached the Saturn system on July 1, 2004 and entered orbit around the planet. The main objectives were to study the structure and dynamics of the rings and satellites, as well as to study the dynamics of the atmosphere and magnetosphere of Saturn and a detailed study of the planet's largest satellite, Titan. In 2009, a joint American-European project between NASA and ESA appeared to launch the Titan Saturn System Mission to study Saturn and its satellites Titan and Enceladus. During it, the station will fly to the Saturn system for 7-8 years, and then become a satellite of Titan for two years. It will also launch a probe balloon into Titan's atmosphere and a landing module.
The lightest of the outer planets is 14 Earth masses (8.6832·10 25 kg). Uranus was discovered in 1781 by the English astronomer William Herschel using a telescope and named after the Greek god of the sky, Uranus. It turns out that Uranus is visible in the sky with the naked eye, but those who saw it before did not realize that it was a planet, because the light from it was very dim, and the movement was very slow.
Uranus, as well as Neptune, which is similar to it, are classified as “ ice giants", since there are many modifications of ice in their depths.
The atmosphere of Uranus is mainly hydrogen and helium, but traces of methane and solid ammonia are also present. Its atmosphere is the coldest (−224 °C).
Uranus also has a ring system, a magnetosphere, and 27 moons. The axis of rotation of Uranus lies, as it were, “on its side” relative to the plane of rotation of this planet around the Sun. As a result, the planet faces the Sun alternately with the north pole, the south, the equator, and the middle latitudes.
In 1986, the American spacecraft Voyager 2 transmitted close-range images of Uranus to Earth. The images do not show images of such storms as on Jupiter, but, according to observations from Earth, seasonal changes are occurring there, and weather activity has been noticed.
Neptune
Neptune is smaller than Uranus (equatorial radius 24,764 ± 15 km), but its mass is 1.0243·10 26 kg greater than the mass of Uranus and is 17 Earth masses.
It is the farthest planet in the solar system. Its name is associated with the name of Neptune, the Roman god of the seas, so the astronomical symbol is Neptune's trident.
Neptune is the first planet discovered through mathematical calculations rather than observations (Neptune is not visible to the naked eye), and this happened in 1846. This was done by a French mathematician who studied celestial mechanics and worked most of his life at the Paris Observatory - Urbain Jean Joseph Le Verrier.
Although Galileo Galilei observed Neptune in 1612 and 1613, he mistook the planet for a fixed star in conjunction with Jupiter in the night sky. Therefore, the discovery of Neptune is not attributed to Galileo.
Soon its satellite Triton was discovered, but the remaining 12 satellites of the planet were discovered in the 20th century.
Neptune, like Saturn and Pluto, has a ring system.
Neptune's atmosphere, like that of Jupiter and Saturn, is composed primarily of hydrogen and helium, with traces of hydrocarbons and possibly nitrogen, but contains a lot of ice. Neptune's core, like Uranus, consists mainly of ice and rock. The planet appears blue - this is due to traces of methane in the outer layers of the atmosphere.
Neptune's atmosphere has the strongest winds among the planets in the solar system.
Neptune has only been visited by one spacecraft, Voyager 2, which flew close to the planet on August 25, 1989.
This planet, like all the others, holds many mysteries. For example, for unknown reasons, the planet’s thermosphere has an abnormally high temperature. But it is too far from the Sun for it to heat up the thermosphere with ultraviolet radiation. Here's a problem for you, future astronomers. And the Universe sets a lot of such tasks, enough for everyone...
The weather on Neptune is characterized by strong storms and winds reaching almost supersonic speeds (about 600 m/s).
Other bodies of the Solar System
This comets- small bodies of the Solar System, usually only a few kilometers in size, consisting mainly of volatile substances (ices), centaurs- icy comet-like objects, trans-Neptunian objects, located in space beyond Neptune, Kuiper belt- fragments similar to the asteroid belt, but consisting mainly of ice, scattered disk…
There is no exact answer yet to the question of where exactly the solar system ends and interstellar space begins...
The solar system includes the central star and all the natural space objects orbiting it. It was formed by gravitational compression of a gas and dust cloud approximately 4.57 billion years ago. The Solar System includes 8* planets, half of which belong to the terrestrial group: Mercury, Venus, Earth and Mars. They are also called the inner planets in contrast to the outer planets - the giant planets Jupiter, Saturn, Uranus and Neptune, located outside the ring of minor planets.
1. Mercury
The planet closest to the Sun in the Solar System is named after the ancient Roman god of commerce, the fleet-footed Mercury, because it moves across the celestial sphere faster than other planets.
2. Venus
The second planet of the solar system was named in honor of the ancient Roman goddess of love Venus. It is the brightest object in the earth's sky after the Sun and Moon and the only planet in the solar system named after a female deity.
3. Earth
The third planet from the Sun and the fifth largest among all the planets in the Solar System has had its current name since 1400, but who exactly named it that is unknown. The English word Earth comes from an 8th century Anglo-Saxon word meaning earth or ground. This is the only planet in the solar system with a name that is not related to Roman mythology.
4. Mars
The seventh largest planet in the solar system has a reddish tint to its surface due to iron oxide. With such a “bloody” association, the object was named after the ancient Roman god of war, Mars.
5. Jupiter
The largest planet in the solar system is named after the ancient Roman supreme god of thunder. 6. Saturn Saturn is the slowest planet in the solar system, which is symbolically reflected in its first name: it was given in honor of the ancient Greek god of time, Kronos. In Roman mythology, the god of agriculture Saturn turned out to be the analogue of Kronos, and as a result, this name was assigned to the planet.
7. Uranus
The third largest planet in diameter and fourth largest planet in the solar system was discovered in 1781 by the English astronomer William Herschel. The tradition of naming planets was continued, and the international community named the new celestial body in honor of the father of Kronos, the Greek god of the sky, Uranus.
8. Neptune
Discovered on September 23, 1846, Neptune became the first planet discovered through mathematical calculations rather than through regular observations. The large blue giant (this color is due to the hue of the atmosphere) is named after the Roman god of the seas.
Pluto in 2006, it lost its status as a solar system planet and was classified as a dwarf planet and the largest object in the Kuiper belt. It has been the ninth planet of the solar system since its discovery in 1930. The name "Pluto" was first suggested by an eleven-year-old schoolgirl from Oxford, Venetia Bernie. She was interested not only in astronomy, but also in classical mythology, and decided that this name - an ancient Roman version of the name of the Greek god of the underworld - was best suited for a dark, distant and cold world. By voting, astronomers chose this option.
Look at the model of the solar system created in the American desert.
*Recently scientists. Since it does not yet have a full name, and research is still ongoing, we did not include it in the above list.
The planets of the Jupiter group include giant fluid planets (,), which have a powerful thermal reserve in their depths. Based on the composition of the fluid shells, the planets of the Jupiter group are divided into peripheral planets with shells of mostly water composition (Uranus, Neptune) and hydrogen planets occupying an internal position in the solar system (Jupiter, Saturn), with a composition not significantly different from the solar one.
Jupiter
Jupiter is the fifth largest planet from the Sun and the largest planet in the Solar System. Jupiter looks like a golden ball, barely flattened perpendicular to the poles. This planet is 5.2 times farther from the Sun than , and spends almost 12 years on one orbital revolution. Jupiter's equatorial diameter is 142,600 km (11 times the diameter of Earth). The period of Jupiter's revolution around its axis in the equatorial region is 9 hours 50 minutes, near the poles - 9 hours 55 minutes.
Photo of Jupiter (taken by NASA's Juno spacecraft).
Thus, Jupiter, like , does not rotate like a rigid body, since its rotation speed is not the same at different latitudes. Due to its rapid rotation, this planet is strongly compressed at the poles. Jupiter's mass is equal to 318 Earth masses. The average density of its substance is close to the density of the Sun - 1.33 g/cm 3 .
Jupiter's rotation axis is almost perpendicular to the plane of its orbit (inclination 87°). Jupiter's fluid envelope consists mainly of helium (74%) and helium (26%), as well as methane (0.1%) and small amounts of ethane, acetylene, phosphene and water vapor. The atmospheric layer is about 1000 km thick.
The planet is shrouded in a layer of clouds, but all the details on the surface of Jupiter constantly change their appearance, since violent movements occur in this layer associated with the transfer of large amounts of energy. Jupiter consists of crystals and drops of ammonia.
The most revealing feature of the planet is the Great Red Spot, which has been observed for more than 300 years. This is a huge oval formation, measuring about 35,000 x 14,000 km, located between the southern tropical and southern temperate zones. Its color is red, but undergoes changes. Probably, the Great Red Spot is supported by convective cells, through which its substance and internal heat are carried from the depths to the visible surface of Jupiter.
In 1956, radio emission from Jupiter was discovered at a wavelength of 3 cm, which corresponds to thermal radiation with a temperature of 145 K. According to measurements in the infrared range of the outer clouds of Jupiter, it was 130 K. It has already been reliably established that Jupiter emits heat, the amount of which is more than twice that thermal energy it receives from the Sun. Perhaps heat is released due to the fact that the giant planet is constantly shrinking (1 mm per year).
In the center of the planet is a huge iron-stone core that generates a powerful magnetic field. The planet’s magnetic field turned out to be complex and consists of two fields: a dipole (similar to Earth’s), extending up to 1,500,000 km from Jupiter, and a non-dipole, occupying another part of the magnetosphere. The surface magnetic field strength is 20 times greater than on Earth. In addition, Jupiter is also a source of radio bursts (sharp jumps in radiation power) at wavelengths from 4 to 85 m; they occur with a period from a fraction of a second to several minutes or even hours. Long bursts include a whole series of disturbances consisting of peculiar noise storms and thunderstorms. According to modern hypotheses, these bursts are explained by plasma oscillations in the planet’s ionosphere.
Jupiter has 15 satellites. The first 4 satellites were discovered by Galileo (Io, Europa, Ganymede, Callisto). They, as well as the inner, closest satellite Amalthea, move almost in the plane of the planet’s equator. In size, Io and Europa can be compared with the Moon, and Ganymede and Callisto are larger than Mercury, but are significantly inferior to it in mass.
The outer satellites rotate around the planet along highly elongated orbits with large inclination angles to the equator (up to 30°). These are small bodies (from 10 to 120 km), obviously of irregular shape. Jupiter's four outer satellites orbit the planet in the opposite direction. In the equatorial region, Jupiter is surrounded by a system of rings. The rings are located at a distance of 50,000 km from the surface of the planet, the width of the rings is about 1000 km.
Saturn
Saturn is the second largest, but rather light (with an average density of 0.69 g/cm 3) planet in the Solar System. The low density is explained by the fact that giant planets consist primarily of hydrogen and helium. At the same time, in the depths of Saturn the pressure does not reach such high values as on Jupiter, so the density of matter there is less. Like Jupiter, it rotates very quickly on its axis (with an orbital period of about 10 hours) and is therefore noticeably oblate.
Saturn. Photo taken by the Cassini spacecraft (NASA) Spectroscopic studies have made it possible to find some molecules in the atmosphere of Saturn. The planet's interior contains powerful heat, which it emits (2.5 times more than it receives from the Sun). The surface temperature of clouds on Saturn is close to the melting point of methane (-184 ° C), the solid particles of which are most likely contained in the cloud layer of the planet.
Saturn is surrounded by rings (about 3 km thick), which are clearly visible through a telescope in the form of “ears” on both sides of the planet’s disk. They were noticed back in 1610 by Galileo. The plane of the rings practically coincides with the plane of the planet's equator and has a constant inclination to the orbital plane of approximately 27°.
Photo of Saturn's rings taken by Cassini in 2008. The rings of Saturn are one of the most amazing and interesting formations in the solar system. A flat system of rings encircles the planet around the equator and does not touch the surface anywhere. The rings are divided into three main concentric zones, delimited by narrow gaps: the outer ring A (with a diameter of about 275 thousand km), the middle B (the brightest) and the inner ring C, which is relatively transparent. The barely visible parts of the inner ring closest to the planet are designated by the symbol D. The existence of another, almost transparent outer ring has also been discovered. The rings rotate around Saturn and the speed of movement of their inner layers is greater than the outer ones.
The rings of Saturn are a flat system of many small satellites of the planet. Saturn has 17 known moons. The largest satellite is Titan, which is also one of the largest satellites in the solar system in terms of size and mass. The Janus satellite is the closest to Saturn, located almost close to the planet. One of the satellites, Phoebe, moves in orbit with a fairly large eccentricity in the opposite direction.
Uranus
Uranus is the seventh planet from the Sun, with a diameter (with a radius of 25,650 km) almost four times larger than the Earth. Uranus is very far from the Sun and is relatively dimly illuminated. The average density of Uranus (1.58 g/cm3) is slightly greater than the density of Saturn and Jupiter, although the matter in the depths of these giants is much more compressed than on Uranus. According to spectroscopic observations, hydrogen and a small amount of methane were found in the composition of the atmosphere of Uranus; there is also, according to indirect evidence, a relatively large amount of helium. Like other giant planets, Uranus has this composition, probably almost all the way to the center.
Uranus Uranus is still poorly studied, as it is extremely difficult to examine due to its small angular dimensions in the field of view of a telescope. For the same reason, it is impossible to study the patterns of rotation of the planet. It is obvious that Uranus (unlike other planets) rotates around its axis, as if lying on its side. This tilt of the equator creates unusual lighting conditions: at the poles in a certain season, the sun's rays fall almost vertically, and the polar day and night cover (alternately) the entire surface of the planet, except for a narrow strip along the equator.
Since Uranus completes its orbit around the Sun in 84 years, the polar day at its poles lasts 42 years, then gives way to a polar night of the same duration. Only in the equatorial belt of Uranus the Sun regularly rises and sets with a periodicity equal to the axial rotation of the planet. Even in those areas where the Sun is at its zenith, the temperature on the visible surface of the clouds is about -215 ° C. Under such temperature conditions, some gases freeze.
The iron-stony core of Uranus is larger in size (about 8000 km) compared to the terrestrial planets. The generated magnetic field of Uranus is also greater than that of Earth.
An unusual feature of Uranus is a system of rings, the distance of which from the planet is from 1.6 to 1.85 of the radius of Uranus. Narrow rings that look like “thread-like” formations, consisting of many individual opaque and, apparently, very dark particles. In the region of the rings there is a whole system of radiation belts filled with high-energy particles, which are similar to the earth's radiation belts, but are distinguished by high levels of radiation.
Uranus has 6 satellites rotating in orbits whose planes practically coincide with each other. The entire system as a whole is distinguished by an extraordinary tilt - its plane is almost perpendicular to the average plane of all planetary orbits.
Neptune
Neptune is the eighth planet in the solar system and a close analogue of Uranus, but has a slightly larger mass and a slightly smaller radius. The average distance of Neptune from the Sun is 4500000000 km, its orbital period is 164 years and 288 days. Neptune's equatorial diameter is 50,200 km; average density - 2.30 g/cm3.
Neptune The characteristics of Neptune are typical of giant planets, which consist mainly of hydrogen and helium with an admixture of other chemical compounds. Neptune has a heavy core containing silicates and other terrestrial elements. The fluid (mostly water) shell of the atmosphere consists of hydrogen, helium and methane.
Neptune has a strong magnetic field, the axis of which, like that of Uranus, is inclined by about 50° to the axis of rotation and is offset from the center of the planet by about 10,000 km. Unlike the calm, freezing surface of Uranus, strong winds dominate on the surface of Neptune, causing storms from powerful jets of gases that rise from the bowels of the planet. Features on Neptune's surface are very difficult to discern.
Neptune has only two satellites. The first - Triton - is larger in size and mass than the Moon, and has the opposite direction of orbital motion. The second satellite, Nereid, unlike the first, is very small and has a highly elongated orbit. The distance from the satellite to the planet varies from 1,500,000 to 9,600,000 km. The direction of orbital motion is direct.
Pluto It is very difficult to study Pluto due to its considerable distance from the Sun and low illumination. The diameter of Pluto is approximately 3 thousand km. The surface of Pluto, heated by the Sun to -220 ° C, even in the coldest midday areas is apparently covered with snow from frozen methane.
The planet's atmosphere is rarefied and consists of methane gas with a possible admixture of inert gases. The brightness of Pluto varies with a rotation period of 6 days 9 hours. Relatively recently, it became clear that this same periodicity corresponds to the orbital motion of Pluto’s satellite, Charon. The satellite is relatively bright, but is located so close to the planet that its images in photographs merge with the image of Pluto and it looks like the “hump” of the planet. Charon, like Pluto, is an accumulation of cometary matter, that is, a mixture of ice and dust.
It was possible to calculate the mass of the Pluto-Charon system: 1.7% of the mass of the Earth. Almost all of it is concentrated in Pluto, because the diameter of the satellite, judging by its brightness, is small compared to the diameter of the planet. The average density of Pluto is approximately 0.7-1.12 g/cm 3 . Such a low density means that Pluto consists predominantly of light chemical elements and compounds, that is, its composition is similar to that of the giant planets and their satellites.
Planets of the Solar System
According to the official position of the International Astronomical Union (IAU), the organization that assigns names to astronomical objects, there are only 8 planets.
Pluto was removed from the planet category in 2006. because There are objects in the Kuiper belt that are larger/equal in size to Pluto. Therefore, even if we take it as a full-fledged celestial body, then it is necessary to add Eris to this category, which has almost the same size as Pluto.
By MAC definition, there are 8 known planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
All planets are divided into two categories depending on their physical characteristics: terrestrial planets and gas giants.
Schematic representation of the location of the planets
Terrestrial planets
Mercury
The smallest planet in the solar system has a radius of only 2440 km. The period of revolution around the Sun, equated to an earthly year for ease of understanding, is 88 days, while Mercury manages to rotate around its own axis only one and a half times. Thus, his day lasts approximately 59 Earth days. For a long time it was believed that this planet always turned the same side to the Sun, since periods of its visibility from Earth were repeated with a frequency approximately equal to four Mercury days. This misconception was dispelled with the advent of the ability to use radar research and conduct continuous observations using space stations. The orbit of Mercury is one of the most unstable; not only the speed of movement and its distance from the Sun change, but also the position itself. Anyone interested can observe this effect.
Mercury in color, image from the MESSENGER spacecraft
Its proximity to the Sun is the reason why Mercury is subject to the largest temperature changes among the planets in our system. The average daytime temperature is about 350 degrees Celsius, and the nighttime temperature is -170 °C. Sodium, oxygen, helium, potassium, hydrogen and argon were detected in the atmosphere. There is a theory that it was previously a satellite of Venus, but so far this remains unproven. It does not have its own satellites.
Venus
The second planet from the Sun, the atmosphere is almost entirely composed of carbon dioxide. It is often called the Morning Star and the Evening Star, because it is the first of the stars to become visible after sunset, just as before dawn it continues to be visible even when all the other stars have disappeared from view. The percentage of carbon dioxide in the atmosphere is 96%, there is relatively little nitrogen in it - almost 4%, and water vapor and oxygen are present in very small quantities.
Venus in the UV spectrum
Such an atmosphere creates a greenhouse effect; the temperature on the surface is even higher than that of Mercury and reaches 475 °C. Considered the slowest, a Venusian day lasts 243 Earth days, which is almost equal to a year on Venus - 225 Earth days. Many call it Earth's sister because of its mass and radius, the values of which are very close to those of Earth. The radius of Venus is 6052 km (0.85% of Earth's). Like Mercury, there are no satellites.
The third planet from the Sun and the only one in our system where there is liquid water on the surface, without which life on the planet could not have developed. At least life as we know it. The radius of the Earth is 6371 km and, unlike other celestial bodies in our system, more than 70% of its surface is covered with water. The rest of the space is occupied by continents. Another feature of the Earth is the tectonic plates hidden under the planet's mantle. At the same time, they are able to move, albeit at a very low speed, which over time causes changes in the landscape. The speed of the planet moving along it is 29-30 km/sec.
Our planet from space
One revolution around its axis takes almost 24 hours, and a complete passage through the orbit lasts 365 days, which is much longer in comparison with its closest neighboring planets. The Earth's day and year are also accepted as a standard, but this is done only for the convenience of perceiving time periods on other planets. The Earth has one natural satellite - the Moon.
Mars
The fourth planet from the Sun, known for its thin atmosphere. Since 1960, Mars has been actively explored by scientists from several countries, including the USSR and the USA. Not all exploration programs have been successful, but water found at some sites suggests that primitive life exists on Mars, or existed in the past.
The brightness of this planet allows it to be seen from Earth without any instruments. Moreover, once every 15-17 years, during the Confrontation, it becomes the brightest object in the sky, eclipsing even Jupiter and Venus.
The radius is almost half that of Earth and is 3390 km, but the year is much longer - 687 days. He has 2 satellites - Phobos and Deimos .
Visual model of the solar system
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Sun
The Sun is a star that is a hot ball of hot gases at the center of our Solar System. Its influence extends far beyond the orbits of Neptune and Pluto. Without the Sun and its intense energy and heat, there would be no life on Earth. There are billions of stars like our Sun scattered throughout the Milky Way galaxy.
Mercury
Sun-scorched Mercury is only slightly larger than Earth's satellite the Moon. Like the Moon, Mercury is practically devoid of an atmosphere and cannot smooth out the traces of impact from falling meteorites, so it, like the Moon, is covered with craters. The day side of Mercury gets very hot from the Sun, while on the night side the temperature drops hundreds of degrees below zero. There is ice in the craters of Mercury, which are located at the poles. Mercury completes one revolution around the Sun every 88 days.
Venus
Venus is a world of monstrous heat (even more than on Mercury) and volcanic activity. Similar in structure and size to Earth, Venus is covered by a thick and toxic atmosphere that creates a strong greenhouse effect. This scorched world is hot enough to melt lead. Radar images through the powerful atmosphere revealed volcanoes and deformed mountains. Venus rotates in the opposite direction from the rotation of most planets.
Earth is an ocean planet. Our home, with its abundance of water and life, makes it unique in our solar system. Other planets, including several moons, also have ice deposits, atmospheres, seasons and even weather, but only on Earth did all these components come together in a way that made life possible.
Mars
Although details of the surface of Mars are difficult to see from Earth, observations through a telescope indicate that Mars has seasons and white spots at the poles. For decades, people believed that the bright and dark areas on Mars were patches of vegetation, that Mars might be a suitable place for life, and that water existed in the polar ice caps. When the Mariner 4 spacecraft arrived at Mars in 1965, many scientists were shocked to see photographs of the murky, cratered planet. Mars turned out to be a dead planet. More recent missions, however, have revealed that Mars holds many mysteries that remain to be solved.
Jupiter
Jupiter is the most massive planet in our solar system, with four large moons and many small moons. Jupiter forms a kind of miniature solar system. To become a full-fledged star, Jupiter needed to become 80 times more massive.
Saturn
Saturn is the farthest of the five planets known before the invention of the telescope. Like Jupiter, Saturn is composed primarily of hydrogen and helium. Its volume is 755 times greater than that of the Earth. Winds in its atmosphere reach speeds of 500 meters per second. These fast winds, combined with heat rising from the planet's interior, cause the yellow and golden streaks we see in the atmosphere.
Uranus
The first planet found using a telescope, Uranus was discovered in 1781 by astronomer William Herschel. The seventh planet is so far from the Sun that one revolution around the Sun takes 84 years.
Neptune
Distant Neptune rotates almost 4.5 billion kilometers from the Sun. It takes him 165 years to complete one revolution around the Sun. It is invisible to the naked eye due to its vast distance from Earth. Interestingly, its unusual elliptical orbit intersects with the orbit of the dwarf planet Pluto, which is why Pluto is inside the orbit of Neptune for about 20 years out of 248 during which it makes one revolution around the Sun.
Pluto
Tiny, cold and incredibly distant, Pluto was discovered in 1930 and was long considered the ninth planet. But after discoveries of Pluto-like worlds that were even further away, Pluto was reclassified as a dwarf planet in 2006.
Planets are giants
There are four gas giants located beyond the orbit of Mars: Jupiter, Saturn, Uranus, Neptune. They are located in the outer solar system. They are distinguished by their massiveness and gas composition.
Planets of the solar system, not to scale
Jupiter
The fifth planet from the Sun and the largest planet in our system. Its radius is 69912 km, it is 19 times larger than the Earth and only 10 times smaller than the Sun. The year on Jupiter is not the longest in the solar system, lasting 4333 Earth days (less than 12 years). His own day has a duration of about 10 Earth hours. The exact composition of the planet's surface has not yet been determined, but it is known that krypton, argon and xenon are present on Jupiter in much larger quantities than on the Sun.
There is an opinion that one of the four gas giants is actually a failed star. This theory is also supported by the largest number of satellites, of which Jupiter has many - as many as 67. To imagine their behavior in the planet’s orbit, you need a fairly accurate and clear model of the solar system. The largest of them are Callisto, Ganymede, Io and Europa. Moreover, Ganymede is the largest satellite of the planets in the entire solar system, its radius is 2634 km, which is 8% greater than the size of Mercury, the smallest planet in our system. Io has the distinction of being one of only three moons with an atmosphere.
Saturn
The second largest planet and the sixth in the solar system. In comparison with other planets, it is most similar to the Sun in the composition of chemical elements. The radius of the surface is 57,350 km, the year is 10,759 days (almost 30 Earth years). A day here lasts a little longer than on Jupiter - 10.5 Earth hours. In terms of the number of satellites, it is not much behind its neighbor - 62 versus 67. The largest satellite of Saturn is Titan, just like Io, which is distinguished by the presence of an atmosphere. Slightly smaller in size, but no less famous are Enceladus, Rhea, Dione, Tethys, Iapetus and Mimas. It is these satellites that are the objects for the most frequent observation, and therefore we can say that they are the most studied in comparison with the others.
For a long time, the rings on Saturn were considered a unique phenomenon unique to it. Only recently it was established that all gas giants have rings, but in others they are not so clearly visible. Their origin has not yet been established, although there are several hypotheses about how they appeared. In addition, it was recently discovered that Rhea, one of the satellites of the sixth planet, also has some kind of rings.