Terrestrial planets Mars and Venus. Planet Mars: interesting facts about the fiery neighbor of the Earth

Within our native solar system there are a wide variety of cosmic bodies. We call them planets, but each of them has its own, unique properties. Thus, the first four, located closest to the star, are included in the category of “terrestrial planets”. They have a core, a mantle, a solid surface and an atmosphere. The next four are gas giants, having only a core covered with a wide variety of gases. But on our agenda we have Mars and Earth. Comparing these two planets will be fun and exciting, especially since they are both terrestrial planets.

Introduction

Astronomers of the past, after discovering Mars, believed that this planet was the closest relative of the Earth. The first comparisons of Mars and Earth are associated with the system of canals seen through a telescope, which surrounded the red planet. Many were sure that there was water there and, as a result, organic life. It is likely that millions of years ago this object within the solar system had conditions similar to those on Earth today. However, it has now been more than precisely established that Mars is a red desert. Nevertheless, comparisons between Earth and Mars are a favorite topic of astronomers to this day. By studying the structural features and rotation of our closest neighbor, they believe that this planet will soon be able to be colonized. But there are nuances that so far prevent humanity from taking this step. We learn about what they are and what they are by drawing an analogy on all points between our native Earth and the mysterious neighboring Mars.

Weight, size

These indicators are the most important, so we will start with Mars and Earth. Even in children's books on astronomy, we all noticed that the red planet is slightly smaller than ours, about one and a half times. Let's look at this difference in specific numbers.

• The average radius of the Earth is 6371 km, and for Mars this figure is 3396 km.
• The volume of our home planet is 1.08321 x 10 12 km 3, while the Martian volume is equal to 1.6318 × 10¹¹ km³, that is, it is 0.151 of the Earth’s volume.

The mass of Mars is also smaller compared to Earth, and this indicator is radically different from the previous one. The Earth weighs 5.97 x 10 24 kg, and the red planet is content with only 15 percent of this figure, namely 6.4185 x 10 23 kg.

Orbital features

From the same children's astronomy textbooks, we know that Mars, due to the fact that it is more distant from the Sun than the Earth, is forced to walk in a larger orbit. It is about twice as large as the Earth’s, in fact, and the year on the red planet is twice as long. From this we can conclude that this cosmic body rotates at a speed comparable to the Earth. But it is important to know this data in exact numbers. The distance of the Earth from the Sun is 149,598,261 km, but Mars is located at a distance of 249,200,000,000 km from our star, which is almost twice as much. The orbital year in the kingdom of dusty and red desert is 687 days (we remember that on earth the year lasts 365 days).

It is important to note that the sidereal rotation of the two planets is almost the same. A day on Earth is 23 hours and 56 minutes, and on Mars it is 24 hours and 40 minutes. Axial tilt cannot be ignored. For Earth, the characteristic indicator is 23 degrees, and for Mars - 25.19 degrees. It is likely that there may be seasonality on the planet.

Composition and structure

A comparison of Mars and Earth would be incomplete if the structure and density of these two planets is ignored. Their structure is identical, since both belong to the terrestrial group. At the very center is the core. In Earth it consists of nickel and metal, and the radius of its sphere is 3500 km. The Martian core has the same composition, but its spherical radius is 1800 km. Then both planets have a silicate mantle, followed by a dense crust. But the Earth's crust differs from the Martian crust in the presence of a unique element - granite, which is not present anywhere else in space. It is important to note that the depth is on average 40 km, while the Martian crust reaches a depth of up to 125 km. The average is 5.514 grams per cubic meter, and Mars is 3.93 grams per cubic meter.

Temperature and atmosphere

At this point we are faced with fundamental differences between the two neighboring planets. The thing is that in the solar system, only one Earth is equipped with a very dense air shell, which maintains a unique microclimate on the planet. So, a comparison of the atmosphere of Earth and Mars should begin with the fact that in the first the air layer has a complex, five-stage structure. We all learned in school terms like stratosphere, exosphere, etc. The Earth's atmosphere consists of 78 percent nitrogen and 21 percent oxygen. On Mars, there is only one layer, very thin, which consists of 96 percent carbon dioxide, 1.93% argon and 1.89% nitrogen.

This also caused the difference in temperature. On Earth, the average is +14 degrees. It rises to a maximum of +70 degrees, and drops to -89.2. It's much cooler on Mars. The average temperature is -46 degrees, while the minimum is 146 below zero, and the maximum is 35 with a + mark.

Gravity

This word contains the whole essence of our existence on the blue planet. It is the only one in the solar system that can provide a force of gravity acceptable for the life of people, animals and plants. We mistakenly believed that there is no gravity on other planets, but it is worth saying that there is gravity there, just not as strong as ours. The gravity on Mars is almost three times less than on Earth. If we have such an indicator as G - that is, the acceleration of gravity is equal to 9.8 m/s squared, then on the red desert planet it is equal to 3.711 m/s squared. Yes, you can walk on Mars, but, alas, you won’t be able to walk on Mars without a special suit with loads.

Satellites

The only satellite of the Earth is the Moon. It not only accompanies our planet on its mysterious cosmic path, but is also responsible for many natural processes in life, for example, tides. The Moon is also the most studied cosmic body at the moment, since it is closest to us. Escorts of Mars - The satellites were discovered in 1877 and named after the sons of the god of war Ares (translated as “fear” and “horror”). It is most likely that they were pulled by the red planet's gravity from the asteroid ring, since their composition is identical to all other rocks orbiting between Mars and Jupiter.

People have always been interested in the unknown expanses of space. The study of other planets has attracted many scientists, and even the common man is interested in the question of what is there in space? First of all, scientists pay attention to the planets of the solar system. Since they are closest to Earth and are easier to study. The mysterious red planet Mars is being especially actively studied. Let's find out which planet is larger - Mars or Earth, and try to understand why the red celestial body attracts us so much.

Brief description of the planets of the solar system. Their sizes

From Earth, all the planets of our system appear to us as small luminous points that are difficult to see with the naked eye. Mars is different from everyone else - it seems larger to us than the others and sometimes even without telescopic equipment you can see its orange light.

Which planet is bigger: Mars or Earth? Do we see Mars so well because it is huge, or is it simply closer to us? Let's look into this issue. To do this, we will sequentially consider the sizes of all planets belonging to the Solar system. They were divided into two groups.

Terrestrial group of planets

Mercury is the smallest planet. In addition, it is closest to the Sun than anyone else. Its diameter is 4878 km.

Venus is the planet next farthest from the Sun and closest to Earth. Its surface temperature reaches +5000 degrees Celsius. The diameter of Venus is 12103 km.

The earth is different in that it has an atmosphere and water reserves, which made it possible for life to arise. Its size is slightly larger than Venus and is 12,765 km .

Mars is the fourth planet from the Sun. Earth and has a diameter at the equator of 6786 km. Its atmosphere is almost 96% composed of Mars and has a more elongated orbit of rotation than Earth.

Giant planets

Jupiter is the largest of the planets in the solar system. Its diameter is 143,000 km. It consists of gas, which is in a vortex motion. Jupiter rotates around its axis very quickly; it makes a full revolution in about 10 Earth hours. It is surrounded by 16 satellites.

Saturn is a planet that can justifiably be called unique. Its structure has the lowest density. Saturn is also known for its rings, which are 115,000 km wide and 5 km thick. It is the second largest planet in the solar system. Its size is 120,000 km.

Uranus is unusual in that with a telescope it can be seen in blue-green color. This planet also consists of gases that move at a speed of 600 km/h. The diameter is just over 51,000 km.

Neptune is made up of a mixture of gases, most of which are methane. It is because of this that the planet acquired a blue color. Neptune's surface is shrouded in clouds of ammonia and water. The size of the planet is 49,528 km.

The most distant planet from the Sun is Pluto; it does not belong to any of the groups of planets in the Solar System. Its diameter is half that of Mercury and is 2320 km.

Characteristics of the planet Mars. Features of the Red Planet and comparison of its size with the size of the Earth

So we looked at the sizes of all the planets in the solar system. Now we can answer the question of which planet is larger - Mars or Earth. A simple comparison of the diameters of the planets can help with this. The sizes of Mars and Earth differ by half. The Red Planet is almost half the size of our Earth.

Mars is a very interesting space object to study. The mass of the planet is 11% of the temperature on its surface varies throughout the day from +270 to -700 degrees C. The sharp change is due to the fact that the atmosphere of Mars is not so dense and consists mainly of carbon dioxide.

The description of Mars begins with an emphasis on its rich red color. I wonder what caused this? The answer is simple - the soil composition is rich in iron oxides and the increased concentration of carbon dioxide in its atmosphere. For such a specific color, ancient people called the planet bloody and gave it a name in honor of the Roman god of war - Ares.

The surface of the planet is mostly desert, but there are also dark areas, the nature of which has not yet been studied. Mars is a plain, and the southern one is slightly raised from the average level and is dotted with craters.

Many people do not know, but on Mars there is the highest mountain in the entire solar system - Olympus. Its height from base to top is 21 km. The width of this hill is 500 km.

Is it possible

All the works of astronomers are aimed at finding signs of life in space. In order to study Mars for the presence of living cells and organisms on its surface, rovers have repeatedly visited this planet.

Numerous expeditions have already proven that water was previously present on the Red Planet. It is still there, only in the form of ice, and it is hidden under a thin layer of rock soil. The presence of water is also confirmed by photographs in which the beds of Martian rivers are clearly visible.

Many scientists want to prove that humans can adapt to life on Mars. The following facts are provided to support this theory:

1. Almost the same speed of movement of Mars and Earth.
2. Similarity of gravitational fields.
3. Carbon dioxide can be used to produce vital oxygen.

Perhaps in the future, the development of technology will allow us to easily make interplanetary travel and even settle on Mars. But first of all, humanity must preserve and protect its home planet - the Earth, so that it never has to wonder which planet is bigger - Mars or the Earth, and whether the red planet can accept all the migrants who want it.

What is bigger - Mars or Earth? Comparison of the sizes of Mars and Earth

Since ancient times, humanity has turned its gaze to the stars. But if earlier people turned to celestial bodies only as higher beings capable of influencing their lives with their miraculous properties, now these views are much more pragmatic.

Mars in ancient times

The first name given to the planet was Ares. This is how the ancient Greeks named the red planet, which reminded people of war, in honor of the god of war. At a time when no one cared which was bigger, Mars or Earth, power was everything. That is why the ancient Romans replaced the Greeks. They brought their ideas about the world, life, their names. They also renamed the star, symbolizing evil, cruelty and grief. She was named after the Roman god of war, Mars.

Many centuries have passed since then, it has long been found out that it is more, Mars or Earth, it has become clear that the planet is far from being as cruel and powerful as the ancient Greeks and Romans imagined, but interest in the planet has not disappeared, and with each century everything is only intensified.

Life on Mars

The first sketch of Mars was made public in 1659 in Naples. Francesco Fontana, a Neapolitan astronomer and lawyer, initiated a cycle of research that hit the planet over the centuries.

Giovanni Schiaparelli in 1877 surpassed Fontana's achievements by making not just a drawing, but a map of the entire planet. Taking advantage of the Great Confrontation, which allowed him to take a close look at Mars, he discovered certain channels and dark areas on our neighbor in the solar system. Without wasting time thinking about which planet is bigger: Mars or Earth, humanity decided that these were products of an alien civilization. It began to be believed that the canals were irrigation systems that the aliens directed to water the vegetation zones - those very dark areas. The water in the canals, according to most, came from the ice caps at the planet's poles.

The scientist who discovered all these geological objects did not initially have anything like this in mind. However, over time, under the influence of the enthusiasm of the majority, he believed in such a popular hypothesis. He even wrote a work “On Intelligent Life on Mars,” where he explained the ideal straightness of the channels precisely by the activities of alien farmers.

However, already in 1907, a geographer from Great Britain in his book “Is Mars Inhabited?” disproved this theory using all the research available at that time. He finally proved that life on Mars is, in principle, impossible for highly organized beings, despite the fact that Mars is larger or smaller in size than the Earth.

Video on the topic

The truth about channels

The existence of arrow-straight channels was confirmed by photographs of the planet in 1924. Surprisingly, most astronomers observing Mars have never seen this phenomenon. However, by 1939, by the time of the next Great Confrontation, about 500 channels were counted in images of the planet.

Everything was finally clarified only in 1965, when Mariner 4 flew so close to Mars that it was able to photograph it from a distance of only 10 thousand kilometers. These images showed a lifeless desert with craters. All dark zones and channels turned out to be just an illusion caused by distortion during observations through a telescope. There is nothing like this in reality on the planet.

Mars

So, what is bigger: Mars or Earth? The mass of Mars is only 10.7% of the mass of the Earth. Its diameter at the equator is almost half that of Earth - 6,794 kilometers versus 12,756 km. A year on Mars lasts 687 Earth days, a day is 37 minutes longer than ours. There is a change of seasons on the planet, but no one would rejoice at the onset of summer on Mars - this is the harshest season, winds of up to 100 m/s sweep the planet, clouds of dust cover the sky, blocking sunlight. However, the winter months also cannot please us with the weather - the temperature does not rise above minus one hundred degrees. The atmosphere consists of carbon dioxide, which lies in huge snow caps at the planet's poles during the winter months. These hats never completely melt. The density of the atmosphere is only one percent of the earth's.

But you don’t need to think that there is no water on the planet - at the foot of the largest volcanic mountain in the solar system - Olympus - huge glaciers of ordinary water have been found. Their thickness reaches one hundred meters, the total area is several thousand kilometers. In addition, formations similar to dried up river beds were found on the surface. The results of the study prove that fast flows of water once flowed along these rivers.

Research

In the 20th century, not only unmanned space stations were sent to Mars, but also rovers were launched, thanks to which it became possible to obtain soil samples of the red planet. Now we have accurate data on the chemical composition of the atmosphere and surface of the planet, on the nature of its seasons, and we have photographs of all areas of Mars. NASA's Mars rovers, reconnaissance satellite and orbiter have a busy schedule, with literally not a single free minute until 2030.

Prospects

It is no secret that humanity spends enormous, simply cosmic, funds on the study of Mars. The answer to the question of what is bigger, Mars or Earth, has long been answered, but we have not lost interest in this planet. What's the matter? What interested scientists so much that states spent such sums on studying the barren desert?

Although it is entirely possible to have rare earth elements, mining them and transporting them to Earth is simply not cost-effective. Science for science's sake? Perhaps, but not in the situation that is now developing on our own planet to waste resources on studying empty planets.

The fact is that today, when even a child will not ask the question of how much larger Mars is than the Earth, the problem of overpopulation of the blue planet is very acute. In addition to the immediate shortage of living space, the need for fresh water and food is also increasing, and the political and economic situation is deteriorating in all areas, especially environmentally favorable zones. And the more active a person lives, the faster we move towards disaster.

The idea of ​​the “Golden Billion” has long been put forward, according to which one billion people can live safely on Earth. The rest need...

And this is where Mars can come to the rescue. Whether it is larger or smaller than the Earth is not so important in this case. Its total area is approximately equal to the land area of ​​our planet. Thus, it is quite possible to settle a couple of billion people on it. The distance to Mars is not critical; the journey to it will take much less time than in ancient times it took from Rome to China. But it was regularly done by traders. Thus, all that remains is to create favorable conditions for the life of earthlings on Mars. And this will be quite possible after some time, because scientific progress is moving forward with giant steps.

And it is unknown who will win this competition, Earth and Mars: which is more suitable for life in a few decades - the answer to this question awaits us ahead.

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 notice 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...

Mars is the fourth most distant planet from the Sun and the seventh largest planet in the solar system, named after Mars, the ancient Roman god of war, corresponding to the ancient Greek Ares. Mars is sometimes called the “red planet” because of the reddish tint of its surface given by iron oxide.

Mars is a terrestrial planet with a thin atmosphere. Features of the surface relief of Mars can be considered impact craters like those on the Moon, as well as volcanoes, valleys, deserts and polar ice caps like those on Earth.

Mars has two natural satellites, Phobos and Deimos (translated from ancient Greek as “fear” and “terror” - the names of the two sons of Ares who accompanied him in battle), which are relatively small and irregular in shape. They may be asteroids captured by the gravitational field of Mars, similar to asteroid (5261) Eureka from the Trojan group.

The topography of Mars has many unique features. The Martian extinct volcano Mount Olympus is the highest mountain in the solar system, and Valles Marineris is the largest canyon. Additionally, in June 2008, three papers published in the journal Nature provided evidence for the largest known impact crater in the solar system in the northern hemisphere of Mars. Its length is 10,600 km and its width is 8,500 km, which is about four times larger than the largest impact crater previously also discovered on Mars, near its south pole. In addition to similar surface topography, Mars has a rotation period and seasonal cycles similar to Earth's, but its climate is much colder and drier than Earth's.

Until the first flyby of Mars by the Mariner 4 spacecraft in 1965, many researchers believed that there was liquid water on its surface. This opinion was based on observations of periodic changes in light and dark areas, especially in the polar latitudes, which were similar to continents and seas. Dark grooves on the surface of Mars have been interpreted by some observers as irrigation channels for liquid water. It was later proven that these grooves were an optical illusion.

Due to low pressure, water cannot exist in a liquid state on the surface of Mars, but it is likely that conditions were different in the past, and therefore the presence of primitive life on the planet cannot be ruled out. On July 31, 2008, ice water was discovered on Mars by NASA's Phoenix spacecraft.

In February 2009, the orbital exploration constellation orbiting Mars included three operational spacecraft: Mars Odyssey, Mars Express and Mars Reconnaissance Satellite, more than around any other planet except Earth. The surface of Mars has currently been explored by two rovers: Spirit and Opportunity. There are also several inactive landers and rovers on the surface of Mars that have completed exploration. The geological data they collected suggests that most of the surface of Mars was previously covered by water. Observations over the past decade have revealed weak geyser activity in some places on the surface of Mars. According to observations from NASA's Mars Global Surveyor spacecraft, parts of Mars' south polar cap are gradually retreating.

Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches −2.91m (at its closest approach to the Earth), second in brightness only to Jupiter (and not always during a great opposition) and Venus (but only in the morning or evening). Typically, during a great opposition, orange Mars is the brightest object in Earth's night sky, but this only occurs once every 15-17 years for one to two weeks.

Mars is almost half the size of Earth - its equatorial radius is 3396.9 km (53.2% of Earth's). The surface area of ​​Mars is approximately equal to the land area on Earth. The polar radius of Mars is approximately 20 km less than the equatorial radius, although the planet's rotation period is longer than that of the Earth, which suggests a change in the rotation speed of Mars over time. The planet's mass is 6.418×1023 kg (11% of the Earth's mass). The acceleration of gravity at the equator is 3.711 m/s² (0.378 Earth); the first escape velocity is 3.6 km/s and the second is 5.027 km/s. Mars rotates around its axis, inclined to the perpendicular to the orbital plane at an angle of 24°56′. The planet's rotation period is 24 hours 37 minutes 22.7 seconds. Thus, a Martian year consists of 668.6 Martian solar days (called sols). The tilt of Mars' rotation axis causes the seasons to change. In this case, the elongation of the orbit leads to large differences in their duration. Thus, the northern spring and summer, taken together, last 371 sols, that is, significantly more than half of the Martian year. At the same time, they occur in a section of Mars’ orbit that is distant from the Sun. Therefore, on Mars, the northern summer is long and cool, and the southern summer is short and hot.

Temperatures on the planet range from −153°C at the poles in winter to over 20°C at the equator at midday. The average temperature is −50 °C.

Atmosphere of Mars.

The atmosphere of Mars, consisting mainly of carbon dioxide, is very thin. The pressure at the surface of Mars is 160 times less than on Earth - 6.1 mbar at the average surface level. Due to the large difference in altitude on Mars, the pressure at the surface varies greatly. The maximum value reaches 10-12 mbar in the Hellas basin at a depth of 8 km. Unlike Earth, the mass of the Martian atmosphere varies greatly throughout the year due to the melting and freezing of the polar caps containing carbon dioxide.

The atmosphere consists of 95% carbon dioxide; it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 0.1% water vapor, 0.07% carbon monoxide. There are traces of methane.

The Martian ionosphere extends from 110 to 130 km above the planet's surface.

There is evidence that in the past the atmosphere could have been denser, and the climate warm and humid, and there was liquid water and rain on the surface of Mars. The Mars Odyssey orbital probe has discovered that there are deposits of water ice under the surface of the red planet. Later, this assumption was confirmed by other devices, but the question of the presence of water on Mars was finally resolved in 2008, when the Phoenix probe, which landed near the planet’s north pole, received water from the Martian soil.

The climate, like on Earth, is seasonal. During the cold season, even outside the polar caps, light frost can form on the surface. The Phoenix apparatus recorded snowfall, but the snowflakes evaporated before reaching the surface.

According to researchers from the Carl Sagan Center, a warming process has been underway on Mars in recent decades. Other experts believe that it is too early to draw such conclusions.

Numerous dust devils were detected by the Opportunity rover. These are air vortices that arise near the surface of the planet and lift large amounts of sand and dust into the air. They are often observed on Earth, but on Mars they can reach much larger sizes.

Two-thirds of the surface of Mars is occupied by light areas called continents, about a third are dark areas called seas. The seas are concentrated mainly in the southern hemisphere of the planet, between 10 and 40° latitude. In the northern hemisphere there are only two large seas - Acidalia and Greater Syrtis.

The nature of the dark areas is still a matter of debate. They persist despite dust storms raging on Mars. At one time, this supported the assumption that dark areas were covered with vegetation. Now it is believed that these are simply areas from which, due to their topography, dust is easily blown away. Large-scale images show that, in fact, the dark areas consist of groups of dark streaks and spots associated with craters, hills and other obstacles in the path of winds. Seasonal and long-term changes in their size and shape are apparently associated with a change in the ratio of surface areas covered with light and dark matter.

The hemispheres of Mars differ quite greatly in the nature of their surface. In the southern hemisphere, the surface is 1-2 km above the average level and is densely dotted with craters. This part of Mars resembles the lunar continents. In the north, most of the surface is below average, there are few craters, and the bulk is relatively smooth plains, probably formed by lava flooding and erosion. This hemispheric difference remains a matter of debate. The boundary between the hemispheres follows approximately a great circle inclined 30° to the equator. The boundary is wide and irregular and forms a slope towards the north. Along it are the most eroded areas of the Martian surface.

Two alternative hypotheses have been put forward to explain hemispheric asymmetry. According to one of them, at an early geological stage, lithospheric plates “moved together” (perhaps accidentally) into one hemisphere, like the continent of Pangea on Earth, and then “froze” in this position. Another hypothesis suggests a collision between Mars and a cosmic body the size of Pluto.

The large number of craters in the southern hemisphere suggests that the surface here is ancient - 3-4 billion years old. There are several types of craters: large flat-bottomed craters, smaller and younger bowl-shaped craters similar to the Moon, rimmed craters, and raised craters. The last two types are unique to Mars—rimmed craters formed where liquid ejecta flowed across the surface, and raised craters formed where a blanket of crater ejecta protected the surface from wind erosion. The largest feature of impact origin is the Hellas Plain (approximately 2100 km across).

In the area of ​​chaotic landscape near the hemispheric boundary, the surface experienced large areas of fracture and compression, sometimes followed by erosion (due to landslides or catastrophic release of groundwater), as well as flooding by liquid lava. Chaotic landscapes often lie at the head of large channels cut by water. The most acceptable hypothesis for their joint formation is the sudden melting of subsurface ice.

In the northern hemisphere, in addition to vast volcanic plains, there are two areas of large volcanoes - Tharsis and Elysium. Tharsis is a vast volcanic plain with a length of 2000 km, reaching an altitude of 10 km above the average level. There are three large shield volcanoes on it - Mount Arsia, Mount Pavlina and Mount Askrian. On the edge of Tharsis is Mount Olympus, the highest on Mars and in the solar system. Olympus reaches 27 km in height relative to its base and 25 km in relation to the average surface level of Mars, and covers an area of ​​550 km in diameter, surrounded by cliffs that in some places reach 7 km in height. The volume of Olympus is 10 times greater than the volume of the largest volcano on Earth, Mauna Kea. There are also several smaller volcanoes located here. Elysium is an elevation up to six kilometers above the average level, with three volcanoes - Hecate's Dome, Mount Elysium and Albor Dome.

The Tharsis Rise is also crossed by many tectonic faults, often very complex and extensive. The largest of them, the Valles Marineris, stretches in a latitudinal direction for almost 4000 km (a quarter of the planet’s circumference), reaching a width of 600 km and a depth of 7-10 km; This fault is comparable in size to the East African Rift on Earth. The largest landslides in the solar system occur on its steep slopes. Valles Marineris is the largest known canyon in the solar system. The canyon, which was discovered by the Mariner 9 spacecraft in 1971, could cover the entire United States, from ocean to ocean.

The appearance of Mars varies greatly depending on the time of year. First of all, the changes in the polar ice caps are striking. They wax and wane, creating seasonal patterns in the atmosphere and surface of Mars. The southern polar cap can reach a latitude of 50°, the northern one - also 50°. The diameter of the permanent part of the northern polar cap is 1000 km. As the polar cap in one hemisphere recedes in the spring, features on the planet's surface begin to darken. To an observer on Earth, the darkening wave appears to be spreading from the polar cap toward the equator, although orbiters do not detect any significant changes.

The polar caps consist of two components: seasonal - carbon dioxide and secular - water ice. According to data from the Mars Express satellite, the thickness of the caps can range from 1 m to 3.7 km. The Mars Odyssey probe discovered active geysers on the southern polar cap of Mars. According to NASA experts, jets of carbon dioxide with spring warming burst upward to great heights, taking with them dust and sand.

The spring melting of the polar caps leads to a sharp increase in atmospheric pressure and the movement of large masses of gas to the opposite hemisphere. The speed of the winds blowing in this case is 10-40 m/s, sometimes up to 100 m/s. The wind lifts large amounts of dust from the surface, leading to dust storms. Severe dust storms almost completely obscure the surface of the planet. Dust storms have a noticeable effect on the temperature distribution in the Martian atmosphere.

Data from the Mars Reconnaissance Satellite made it possible to detect a significant layer of ice under rocky screes at the foot of the mountains. The glacier, hundreds of meters thick, covers an area of ​​thousands of square kilometers, and its further study could provide information about the history of the Martian climate.

There are many geological formations on Mars that resemble water erosion, particularly dry river beds. According to one hypothesis, these channels could have been formed as a result of short-term catastrophic events and are not evidence of the long-term existence of the river system. However, recent evidence suggests that the rivers flowed over geologically significant periods of time. In particular, inverted channels (that is, channels raised above the surrounding area) were discovered. On Earth, such formations are formed due to the long-term accumulation of dense bottom sediments, followed by drying and weathering of the surrounding rocks. In addition, there is evidence of shifting channels in the river delta as the surface gradually rises.

Data from NASA's Mars rovers Spirit and Opportunity also indicate the presence of water in the past (minerals were found that could only have formed as a result of prolonged exposure to water). The Phoenix apparatus discovered ice deposits directly in the ground.

Several unusual deep wells have been discovered on the Tharsis volcanic upland. Judging by the image of the Mars Reconnaissance Satellite taken in 2007, one of them has a diameter of 150 meters, and the illuminated part of the wall goes no less than 178 meters deep. A hypothesis has been put forward about the volcanic origin of these formations.

The elemental composition of the surface layer of Martian soil, according to data from landers, is not the same in different places. The main component of the soil is silica (20-25%), containing an admixture of iron oxide hydrates (up to 15%), giving the soil a reddish color. There are significant impurities of sulfur, calcium, aluminum, magnesium, and sodium compounds (a few percent for each).

According to data from NASA's Phoenix probe (landing on Mars on May 25, 2008), the pH ratio and some other parameters of Martian soils are close to those on Earth, and it would theoretically be possible to grow plants on them. “In fact, we found that the soil on Mars meets the requirements and also contains the necessary elements for the emergence and maintenance of life both in the past, present and future.” “We were pleasantly surprised by the data obtained. This type of soil is widely represented here on Earth - any rural resident deals with it every day in their garden. A high (much more than expected) content of alkalis was noted in it, and ice crystals were found. This soil is quite suitable for growing various plants, such as asparagus. There is nothing here that makes life impossible. Quite the contrary: with each new study we find additional evidence in favor of the possibility of its existence,” said the lead chemist of the project, Sam Kuneyves.

There is also a significant amount of water ice in the ground at the landing site.

Unlike Earth, there is no movement of lithospheric plates on Mars. As a result, volcanoes can exist for a much longer time and reach gigantic sizes.

Current models of the internal structure of Mars suggest that Mars consists of a crust with an average thickness of 50 km (and a maximum thickness of up to 130 km), a silicate mantle with a thickness of 1800 km and a core with a radius of 1480 km. The density at the center of the planet should reach 8.5 g/cm³. The core is partially liquid and consists mainly of iron with an admixture of 14-17% (by mass) sulfur, and the content of light elements is twice as high as in the Earth's core. According to modern estimates, the formation of the core coincided with the period of early volcanism and lasted about a billion years. The partial melting of mantle silicates took approximately the same time. Due to the lower gravity on Mars, the pressure range in the Martian mantle is much smaller than on Earth, which means there are fewer phase transitions. It is assumed that the phase transition of olivine into the spinel modification begins at fairly large depths - 800 km (400 km on Earth). The nature of the relief and other features suggest the presence of an asthenosphere, consisting of zones of partially molten matter. A detailed geological map has been compiled for some areas of Mars.

According to observations from orbit and analysis of a collection of Martian meteorites, the surface of Mars consists mainly of basalt. There is some evidence to suggest that on parts of the Martian surface the material is more quartz-rich than ordinary basalt and may be similar to andesitic rocks on Earth. However, these same observations can be interpreted in favor of the presence of quartz glass. Much of the deeper layer consists of granular gland oxide dust.

Mars has a magnetic field, but it is weak and extremely unstable; at different points on the planet its strength can differ from 1.5 to 2 times, and the magnetic poles do not coincide with the physical ones. This suggests that the iron core of Mars is relatively immobile in relation to its crust, that is, the planetary dynamo mechanism responsible for the Earth’s magnetic field does not work on Mars. Although Mars does not have a stable planetary magnetic field, observations have shown that parts of the planetary crust are magnetized and that the magnetic poles of these parts have changed in the past. The magnetization of these parts turned out to be similar to strip magnetic anomalies in the world's oceans.

One theory, published in 1999 and retested in 2005 (with the help of the unmanned Mars Global Surveyor), these stripes show plate tectonics 4 billion years ago before the planet's dynamo ceased to function, causing a sharp weakening magnetic field. The reasons for this sharp weakening are unclear. There is an assumption that the functioning of the dynamo 4 billion. years ago is explained by the presence of an asteroid that revolved at a distance of 50-75 thousand kilometers around Mars and caused instability in its core. The asteroid then fell to the Roche limit and collapsed. However, this explanation itself contains ambiguities and is disputed in the scientific community.

Perhaps in the distant past, as a result of a collision with a large celestial body, the rotation of the core stopped, as well as the loss of the main volume of the atmosphere. The loss of the magnetic field is believed to have occurred about 4 billion years ago. Due to the weakness of the magnetic field, the solar wind penetrates almost unhindered into the Martian atmosphere, and many of the photochemical reactions under the influence of solar radiation that occur in the ionosphere and above on Earth can be observed on Mars almost at its very surface.

The geological history of Mars includes the following three eras:
Noachian Age (named after the "Noachian Land", a region of Mars): Formation of the oldest surviving surface of Mars. It continued from 4.5 billion to 3.5 billion years ago. During this era, the surface was scarred by numerous impact craters. The Tharsis plateau was probably formed during this period, with intense water flow later.
Hesperian era: from 3.5 billion years ago to 2.9 - 3.3 billion years ago. This era is marked by the formation of huge lava fields.
Amazonian Age (named after the "Amazonian Plain" on Mars): 2.9 - 3.3 billion years ago to the present day. The areas formed during this era have very few meteorite craters, but are otherwise completely different. Mount Olympus was formed during this period. At this time, lava flows were spreading in other parts of Mars.

The natural satellites of Mars are Phobos and Deimos. Both of them were discovered by American astronomer Asaph Hall in 1877. Phobos and Deimos are irregular in shape and very small in size. According to one hypothesis, they may represent asteroids like (5261) Eureka from the Trojan group of asteroids captured by the gravitational field of Mars. The satellites are named after the characters accompanying the god Ares (that is, Mars), Phobos and Deimos, personifying fear and horror who helped the god of war in battles.

Both satellites rotate around their axes with the same period as around Mars, so they always face the same side towards the planet. The tidal influence of Mars gradually slows down the movement of Phobos, and will ultimately lead to the satellite falling onto Mars (if the current trend continues), or to its disintegration. On the contrary, Deimos is moving away from Mars.

Phobos (top) and Deimos (bottom).

Both satellites have a shape approaching a triaxial ellipsoid; Phobos (26.6 × 22.2 × 18.6 km) is slightly larger than Deimos (15 × 12.2 × 10.4 km). The surface of Deimos appears much smoother due to the fact that most of the craters are covered with fine-grained material. Obviously, on Phobos, which is closer to the planet and more massive, the substance ejected during meteorite impacts either caused repeated impacts on the surface or fell on Mars, while on Deimos it remained in orbit around the satellite for a long time, gradually settling and hiding uneven terrain.

The popular idea that Mars was inhabited by intelligent Martians became widespread at the end of the 19th century. Schiaparelli's observations of the so-called canals, combined with Percival Lowell's book on the same topic, popularized the idea of ​​a planet whose climate was becoming drier, colder, dying and in which there existed an ancient civilization carrying out irrigation works.

Numerous other sightings and announcements by famous people have given rise to the so-called “Mars Fever” around this topic. In 1899, while studying atmospheric interference in radio signals using receivers at the Colorado Observatory, inventor Nikola Tesla observed a repeating signal. He then suggested that it could be a radio signal from other planets, such as Mars. In a 1901 interview, Tesla said that he had the idea that interference could be caused artificially. Although he could not decipher their meaning, it was impossible for him that they arose completely by chance. In his opinion, this was a greeting from one planet to another.

Tesla's theory attracted the enthusiastic support of Lord Kelvin, who, visiting the United States in 1902, said that he believed Tesla had picked up a signal from the Martians sent to the United States. However, Kelvin then began to strongly deny this statement before leaving America: “In fact, I said that the inhabitants of Mars, if they existed, could certainly see New York, especially the light from electricity.”

Today, the presence of liquid water on its surface is considered a condition for the development and maintenance of life on the planet. There is also a requirement that the planet's orbit be in the so-called habitable zone, which for the Solar System begins behind Venus and ends with the semimajor axis of the orbit of Mars. During perihelion, Mars is inside this zone, but a thin atmosphere with low pressure prevents the appearance of liquid water over a large area for a long period. Recent evidence suggests that any water on the surface of Mars is too salty and acidic to support permanent Earth-like life.

The lack of a magnetosphere and the extremely thin atmosphere of Mars are also a challenge to supporting life. There is a very weak movement of heat flows on the surface of the planet; it is poorly insulated from bombardment by solar wind particles; in addition, when heated, water instantly evaporates, bypassing the liquid state due to low pressure. Mars is also on the threshold of the so-called. "geological death". The end of volcanic activity apparently stopped the circulation of minerals and chemical elements between the surface and interior of the planet.

Evidence suggests that the planet was previously much more prone to supporting life than it is now. However, to date, no remains of organisms have been found on it. The Viking program, carried out in the mid-1970s, conducted a series of experiments to detect microorganisms in Martian soil. It has produced positive results, such as a temporary increase in CO2 emissions when soil particles are placed in water and growing medium. However, this evidence of life on Mars was then disputed by some scientists. This led to their lengthy dispute with NASA scientist Gilbert Levin, who claimed that Viking had discovered life. After re-evaluating the Viking data in light of current scientific knowledge about extremophiles, it was determined that the experiments conducted were not advanced enough to detect these life forms. Moreover, these tests could even kill the organisms even if they were contained in the samples. Tests conducted as part of the Phoenix program showed that the soil has a very alkaline pH and contains magnesium, sodium, potassium and chloride. There are enough nutrients in the soil to support life, but life forms must be protected from intense ultraviolet light.

It is interesting that in some meteorites of Martian origin formations were found that are shaped like the simplest bacteria, although they are inferior in size to the smallest terrestrial organisms. One such meteorite is ALH 84001, found in Antarctica in 1984.

Based on observations from Earth and data from the Mars Express spacecraft, methane was discovered in the atmosphere of Mars. Under Mars conditions, this gas decomposes quite quickly, so there must be a constant source of replenishment. Such a source could be either geological activity (but no active volcanoes have been found on Mars) or the activity of bacteria.

After the landing of automatic vehicles on the surface of Mars, it became possible to conduct astronomical observations directly from the surface of the planet. Due to the astronomical position of Mars in the solar system, the characteristics of the atmosphere, the orbital period of Mars and its satellites, the picture of the night sky of Mars (and astronomical phenomena observed from the planet) differs from that on Earth and in many ways appears unusual and interesting.

During sunrise and sunset, the Martian sky at the zenith has a reddish-pink color, and in the immediate vicinity of the solar disk - from blue to violet, which is completely opposite to the picture of earthly dawns.

At noon, the sky of Mars is yellow-orange. The reason for such differences from the colors of the earth's sky is the properties of the thin, rarefied, dust-containing atmosphere of Mars. On Mars, Rayleigh scattering of rays (which on Earth is the reason for the blue color of the sky) plays an insignificant role, its effect is weak. Presumably, the yellow-orange color of the sky is also caused by the presence of 1% magnetite in dust particles constantly suspended in the Martian atmosphere and raised by seasonal dust storms. Twilight begins long before sunrise and lasts long after sunset. Sometimes the color of the Martian sky takes on a purple hue as a result of light scattering on microparticles of water ice in the clouds (the latter is a rather rare phenomenon).

The Earth is an inner planet to Mars, just as Venus is to the Earth. Accordingly, from Mars, the Earth is observed as a morning or evening star, rising before dawn or visible in the evening sky after sunset.

The maximum elongation of the Earth in the sky of Mars will be 38 degrees. To the naked eye, the Earth will be visible as a bright (maximum visible magnitude about −2.5) greenish star, next to which the yellowish and fainter (about 0.9) star of the Moon will be easily visible. Through a telescope, both objects will show the same phases. The revolution of the Moon around the Earth will be observed from Mars as follows: at the maximum angular distance of the Moon from the Earth, the naked eye can easily separate the Moon and the Earth: after a week, the “stars” of the Moon and Earth will merge into a single star, inseparable by the eye; after another week, the Moon will again be visible at its maximum distance, but on the other side from the Earth. From time to time, an observer on Mars will be able to see the passage (transit) of the Moon across the Earth's disk or, conversely, the covering of the Moon by the Earth's disk. The maximum apparent distance of the Moon from the Earth (and their apparent brightness) when observed from Mars will vary significantly depending on the relative positions of the Earth and Mars, and, accordingly, the distance between the planets. In eras of opposition it will be about 17 minutes of arc, at the maximum distance between Earth and Mars - 3.5 minutes of arc. The Earth, like other planets, will be observed in the band of Zodiac constellations. An astronomer on Mars will also be able to observe the passage of the Earth across the disk of the Sun, the closest one occurring on November 10, 2084.

The angular size of the Sun observed from Mars is smaller than that visible from Earth and is 2/3 of the latter. Mercury from Mars will be virtually inaccessible to observation with the naked eye due to its extreme proximity to the Sun. The brightest planet in the sky of Mars is Venus, Jupiter is in second place (its four largest satellites can be observed without a telescope), and Earth is in third place.

Phobos, when observed from the surface of Mars, has an apparent diameter of about 1/3 of the disk of the Moon in the Earth's sky and an apparent magnitude of about −9 (approximately the same as the Moon in its first quarter phase). Phobos rises in the west and sets in the east, only to rise again 11 hours later, thus crossing the Martian sky twice a day. The movement of this fast moon across the sky will be easily noticeable throughout the night, as will the changing phases. The naked eye will be able to discern the largest relief feature of Phobos - the Stickney crater. Deimos rises in the east and sets in the west, appears as a bright star without a noticeable visible disk, magnitude about −5 (slightly brighter than Venus in Earth's sky), slowly crossing the sky over the course of 2.7 Martian days. Both satellites can be observed in the night sky at the same time, in this case Phobos will move towards Deimos.

Both Phobos and Deimos are bright enough for objects on the surface of Mars to cast clear shadows at night. Both satellites have a relatively low orbital inclination to the equator of Mars, which precludes their observation in the high northern and southern latitudes of the planet: for example, Phobos never rises above the horizon north of 70.4° N. w. or south of 70.4° S. sh.; for Deimos these values ​​are 82.7° N. w. and 82.7° S. w. On Mars, an eclipse of Phobos and Deimos can be observed as they enter the shadow of Mars, as well as an eclipse of the Sun, which is only annular due to the small angular size of Phobos compared to the solar disk.

The North Pole on Mars, due to the tilt of the planet's axis, is located in the constellation Cygnus (equatorial coordinates: right ascension 21h 10m 42s, declination +52° 53.0′ and is not marked by a bright star: the closest to the pole is a dim sixth magnitude star BD +52 2880 (others its designations are HR 8106, HD 201834, SAO 33185).The south celestial pole (coordinates 9h 10m 42s and −52° 53.0) is located a couple of degrees from the star Kappa Parus (apparent magnitude 2.5) - its, in principle, , can be considered the South Pole Star of Mars.

The zodiacal constellations of the Martian ecliptic are similar to those observed from Earth, with one difference: when observing the annual movement of the Sun among the constellations, it (like other planets, including the Earth), leaving the eastern part of the constellation Pisces, will pass for 6 days through the northern part of the constellation Cetus in front of how to re-enter western Pisces.

Due to the proximity of Mars to Earth, its colonization in the foreseeable future is an important task for humanity. Natural conditions relatively close to those on Earth make this task easier. In particular, there are places on Earth that have been explored by man, in which the natural conditions are in many ways similar to those on Mars. Atmospheric pressure at an altitude of 34,668 meters - the record high point reached by a balloon with a crew on board (May 1961) - approximately corresponds to the pressure on the surface of Mars. The extremely low temperatures in the Arctic and Antarctica are comparable to even the lowest temperatures on Mars, and the equator of Mars in the summer months is as warm (+30 °C) as on Earth. There are also deserts on Earth that are similar in appearance to the Martian landscape.

However, there are several significant differences between Earth and Mars. In particular, Mars' magnetic field is approximately 800 times weaker than Earth's. Together with the rarefied atmosphere, this increases the amount of ionizing radiation reaching its surface. Radiation measurements carried out by the American unmanned spacecraft The Mars Odyssey showed that the background radiation in Mars orbit is 2.2 times higher than the background radiation on the International Space Station. The average dose was approximately 220 millirads per day (2.2 milligrays per day or 0.8 grays per year). The amount of radiation received as a result of being in such a background for three years is approaching the established safety limits for astronauts. On the surface of Mars, the background radiation will most likely be somewhat lower and can vary significantly depending on the terrain, altitude and local magnetic fields.

Mars has some economic potential for colonization. In particular, the southern hemisphere of Mars was not subject to melting, unlike the entire surface of the Earth - therefore, the rocks of the southern hemisphere inherited the quantitative composition of the non-volatile component of the protoplanetary cloud. According to calculations, it should be enriched with those elements (relative to the Earth) that on Earth “sank” into its core during the melting of the planet: copper, iron and platinum group metals, tungsten, rhenium, uranium. The export of rhenium, platinum metals, silver, gold and uranium to Earth (if its prices rise to the level of silver prices) has good prospects, but for its implementation it requires the presence of a surface reservoir with liquid water for enrichment processes.

The flight time from Earth to Mars (with current technologies) is 259 days in a semi-ellipse and 70 days in a parabola. To communicate with potential colonies, radio communication can be used, which has a delay of 3-4 minutes in each direction during the closest approach of the planets (the opposition of Mars, from an earthly point of view, which repeats every 780 days), and about 20 minutes. at the maximum distance of the planets (conjunction of Mars with the Sun); see Configuration (astronomy).

However, to date, no practical steps have been taken towards the colonization of Mars.

The exploration of Mars began a long time ago, 3.5 thousand years ago, in Ancient Egypt. The first detailed reports on the position of Mars were compiled by Babylonian astronomers, who developed a number of mathematical methods to predict the planet's position. Using data from the Egyptians and Babylonians, ancient Greek (Hellenistic) philosophers and astronomers developed a detailed geocentric model to explain the movement of the planets. Several centuries later, Indian and Islamic astronomers estimated the size of Mars and its distance from Earth. In the 16th century, Nicolaus Copernicus proposed a heliocentric model to describe the solar system with circular planetary orbits. His results were revised by Johannes Kepler, who introduced a more accurate elliptical orbit of Mars, coinciding with the observed one.

Topographic map of Mars.

In 1659, Francesco Fontana, looking at Mars through a telescope, made the first drawing of the planet. He depicted a black spot in the center of a clearly defined sphere. In 1660, two polar caps were added to the black spot, added by Jean Dominique Cassini. In 1888, Giovanni Schiaparelli, who studied in Russia, gave the first names to individual surface features: the seas of Aphrodite, Erythraean, Adriatic, Cimmerian; lakes Sun, Lunnoe and Phoenix.

The heyday of telescopic observations of Mars occurred at the end of the 19th - mid-20th centuries. It is largely due to public interest and well-known scientific controversies surrounding the observed Martian canals. Among the astronomers of the pre-space era who carried out telescopic observations of Mars during this period, the most famous are Schiaparelli, Percival Lovell, Slifer, Antoniadi, Barnard, Jarry-Deloge, Tikhov, Vaucouleurs. It was they who laid the foundations of areography and compiled the first detailed maps of the surface of Mars - although they turned out to be almost completely incorrect after automatic probes flew to Mars.

Orbital characteristics:
Perihelion
206.62×106 km
1.3812 a. e.
Aphelion
249.23×106 km
1.6660 a. e.
Major shaft (a)
227.92×106 km
1.5236 a. e.
Orbital eccentricity (e)
0,093315
Sidereal period of revolution
686,971 days
1.8808 Earth years
sol 668.5991
Synodic period of revolution
779.94 days
Orbital speed (v)
24.13 km/s (average)
Inclination (i)
1.85061° (relative to the ecliptic plane)
5.65° (relative to the solar equator)
Ascending Node Longitude (Ω)
49.57854°
Periapsis argument (ω)
286.46230°

Satellites:
2 (Phobos and Deimos)
physical characteristics
Flattening
0,00589
Equatorial radius
3396.2 km
Polar radius
3376.2 km
Average radius
3386.2 km
Surface area (S)
144,798,465 km²
Volume (V)
1.6318×1011 km³
0.151 Earth
Weight(m)
6.4185×1023 kg
0.107 Earth
Average density (ρ)
3.9335 g/cm³
Gravity acceleration at the equator (g)
3.711 m/s² (0.378 g)
Second escape velocity (v2)
5.027 km/s
Equatorial rotation speed
868.22 km/h
Rotation period (T)
24 hours 39 minutes and 36 seconds
Axis tilt
24.94°
Right ascension of the north pole (α)
21 h 10 min 44 s
317.68143°
North pole declination (δ)
52.88650°
Albedo
0.250 (Bond)
0.150 (geo.albedo)

Temperature:

min. avg. Max.

Across the planet 186 K 227 K 268 K

Atmosphere:
Atmosphere pressure
0.6-1.0 kPa (0.006-0.01 atm)
Compound:
95.32% Ang. gas

2.7% Nitrogen
1.6% Argon
0.2% Oxygen
0.07% Carbon monoxide
0.03% Water vapor
0.01% Nitric oxide