- closest to the sun terrestrial planet. Radius - 2440 km (for comparison: the radius of the Earth - 6371 km). The surface of Mercury is similar to the surface of the Moon - it is covered with craters, there are also rocky cliffs stretching for hundreds of kilometers, and huge plateaus composed of solidified lava.

The surface of the planet is covered craters from meteorite impacts. The slopes of the craters, their flat bottom are covered with solidified lava flows.

This small planet even has an atmosphere - very rarefied, consisting of helium, hydrogen, potassium, argon, sodium, oxygen, OH, water were also detected. Helium and hydrogen are brought here from the Sun by the solar wind. Potassium and sodium are formed during the radioactive decay of rocks. Where did oxygen and water come from?

Scientists suggest that water appeared when falling on Mercury ice comets. After the fall of comets, ice, under the influence of high temperatures during the day, evaporates, and steam swirls over the planet. There is an assumption that water from the atmosphere can then settle, accumulating in the ancient craters of the north and south poles.

The average daily temperature on the surface of this small planet is almost 350 degrees Celsius. At night, the surface of the planet cools rapidly - to minus 170 degrees.

Rocky jagged cliffs and slopes formed from solidified lava, they stretch for hundreds of kilometers and are called " scarps". For example, a gigantic cliff (about 350 km long and up to 3 km high) has its own name - Discovery. Ridges, as well as faults, were formed during the compression of the planet, which took place when it cooled.

In general, the surface of Mercury is homogeneous - there are no sharp differences in relief, as on Mars or on the Moon.

So, we, as lovers of geology and mineralogy, are interested in the rocks and minerals that make up this still little-studied planet. A spectral analysis of the reflected light of the planet showed that its surface contains little calcium and aluminum (which is also characteristic of the Moon), little titanium, iron, but a lot of magnesium and sulfur.

From this, analytical conclusions were made that the composition of the rocks occupies an intermediate position between basalts(rocks of the main composition) and ultramafic rocks(like komatiites). Where did a large amount of sulfur come from (there is more of it than on other terrestrial planets) is a debatable question.

Formed on the surface of the planet during the outpouring of lava. They, like ultrabasic rocks, are very common on Earth.

On Mercury, basalt spilled over the surface many times, the layers lay one on top of the other for large areas. The surface of the planet has traces of meteorite bombardments. Due to numerous impacts of meteorites, there is a lot of debris and dust on the surface of Mercury, and the surface on the plains is loose.

The thickness of Mercury's crust ranges from 100 to 300 km. The core of Mercury is very massive, it makes up 3/4 of the planet's volume, it consists of iron and nickel, so Mercury has a magnetic field. For comparison, we can say that in terms of volume, the size of the core of this planet is equal to the moon.

What minerals can contain the bowels of Mercury? On the planets of the terrestrial terrestrial group, some conditions for the formation of minerals and rocks were the same, while others differed significantly. According to studies obtained by spacecraft, the basalts and komatiites of Mercury may contain deposits of copper, nickel, chromium, manganese, and other non-ferrous sulfides. One can confidently assume the existence of uranium deposits.

Mercury is lost in the rays of the Sun, so special conditions are needed to observe it. It is known that the famous scientist Nicolaus Copernicus never observed this planet in the sky, which he regretted very much. In January 2015, residents of the northern hemisphere can observe the parade of two planets - Venus and Mercury, this is a very rare occurrence. Mercury can be seen with binoculars, the optics of a good camera, and even with the naked eye. The pictures show photographs of Mercury and Venus taken on January 11, 2015 in the Eastern Sayan Mountains, Sayanogorsk.

Another piece of data received from the American Messenger spacecraft has allowed us to re-evaluate the size of the core of the first planet and replenish knowledge about the topography of this hot world.

The work of a Mercurial intelligence officer named Messenger was recently extended for another year. Meanwhile, at the Planetary Science Conference (43rd LPSC) in Texas, the researchers presented 57 papers on the results of the mission so far.

In particular, judging by the latest data, the core of the first from not only occupies a large proportion of the internal volume, in comparison with the cores, or Venus, but also turned out to be even larger than previous estimates. Mercury's core makes up about 85% of the planet's radius, experts said (previously estimated at about 70%).

Previous work has already shown that its core, despite the small size of the planet, has not yet cooled down and is at least partially liquid. Curious details have now been revealed.

If at the Earth we see a liquid metallic outer core and a solid inner core, then at Mercury, under the silicate crust and mantle, first there is a solid shell of iron sulfide, and then a liquid core, very rich in iron, and even deeper, perhaps again, a solid core, transmits PhysOrg.com.

This picture was obtained by analyzing the gravitational field of the planet and the parameters of its rotation, as well as subsequent modeling. Details of the work can be found in an article in Science Express.

Bright spots on radar images taken by the Arecibo telescope ( yellow), in the pictures from the Messenger exactly match the depressions that are constantly in the shadow (photo by NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington).

Another study was devoted to laser measurement of heights in the northern hemisphere of Mercury. The height difference there turned out to be much less than that of the Moon and Mars.

A characteristic feature of the hemisphere, scientists called the vast lowland in the high northern latitudes, on which there are volcanic plains. These areas have experienced significant changes since the end of the early history planet, that is, after the appearance of large impact basins and the appearance of large volcanic plains.

Interestingly, as a result of rock uplift, some areas of the terrain inside the giant (1550 km diameter) Caloris impact basin are now located above its edges.

Among other discoveries, it is worth mentioning the local gravitational anomalies found on Mercury, including candidates for mass concentrations (mascons), and the newly raised topic of ice deposits near the poles. They are evidenced by the analysis of the relief in combination with the radar images of the planet.

Mercury- the planet closest to the Sun general information about Mercury and other planets you will find in Appendix 1) - the average distance from the Sun is 57,909,176 km. However, the distance from the Sun to Mercury can vary from 46.08 to 68.86 million km. The distance of Mercury from the Earth is from 82 to 217 million km. Mercury's axis is almost perpendicular to the plane of its orbit.

Due to the slight inclination of the axis of rotation of Mercury to the plane of its orbit, there are no noticeable seasonal changes on this planet. Mercury has no satellites.

Mercury is a small planet. Its mass is a twentieth of the mass of the Earth, and the radius is 2.5 times less than the earth's.

Scientists believe that in the center of the planet there is a large iron core - it accounts for 80% of the mass of the planet, and on top - a mantle of stone rocks.

For observations from the Earth, Mercury is a difficult object, since it always has to be observed against the background of the evening or morning dawn low above the horizon, and besides, at this time the observer sees only half of its disk illuminated.

The first to explore Mercury was the American space probe Mariner-10, which in 1974-1975. flew past the planet three times. The maximum approach of this space probe to Mercury was 320 km.

The surface of the planet is like a wrinkled apple peel, it is riddled with cracks, depressions, mountain ranges, the highest of which reach 2-4 km, with sheer ledges-escarps 2-3 km high and hundreds of kilometers long. In a number of regions of the planet, valleys and craterless plains are visible on the surface. The average density of the soil is 5.43 g / cm 3.

On the studied hemisphere of Mercury there is the only flat place - the Heat Plain. It is assumed that this is a frozen lava that erupted from the depths after a collision with a giant asteroid about 4 billion years ago.

Atmosphere of Mercury

The atmosphere of Mercury has an extremely low density. It consists of hydrogen, helium, oxygen, calcium vapor, sodium and potassium (Fig. 1). The planet probably receives hydrogen and helium from the Sun, and metals evaporate from its surface. This thin shell can be called "atmosphere" only with a big stretch. The pressure at the surface of the planet is 500 billion times less than at the surface of the Earth (this is less than in modern vacuum installations on Earth).

General characteristics of the planet Mercury

The maximum surface temperature of Mercury, recorded by sensors, is +410 °C. The average temperature of the night hemisphere is -162 ° C, and the daytime +347 ° C (this is enough to melt lead or tin). Temperature differences due to the change of seasons caused by the elongation of the orbit reach 100 °C on the day side. At a depth of 1 m, the temperature is constant and equal to +75 ° C, because porous soil does not conduct heat well.

Organic life on Mercury is ruled out.

Rice. 1. The composition of the atmosphere of Mercury

Impact basin, 250 kilometers wide, image from the MESSENGER spacecraft

Mercury is a terrestrial planet, as are all the other three inner planets: Venus, Earth and Mars. It is the smallest of them and has a diameter of only 4879 km. What is its composition?

Chemical composition

It is formed by 70% metals and 30% silicate materials. The composition of Mercury is slightly less dense than Earth's with its density of 5.43 g/cm3.

Since the planets are much smaller than the Earth, its gravity does not compress the planet as much, so in fact the planet contains heavy elements in the core.

Astronomers believe that the core is very large and consists mainly of iron.

It occupies up to 42% of the total volume of the planet, while the Earth has only 17%.

The core itself is about 3600 km across. The mantle surrounding it is 600 km thick. Around the mantle is a crust, 100-200 km in size.

The crust is known to contain many mountain ranges that extend for hundreds of kilometers.

Planetary geologists believe that some of the ridges were formed when the planet began to cool, while the other part was formed due to deformations from the impact of large asteroids.

What is this reason that can explain why Mercury has such a large core, and what influenced the nascent planetesimal at the very beginning of its history? It is possible that it formed before our Sun flared up. After the start of thermonuclear fusion in the core of the star, the Sun evaporated part of the planet's surface with a powerful solar wind.

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The closest planet to the Sun is Mercury. Astronomers have spent many decades studying this planet, but there are still more questions than answers. On the other hand, a lot is also known about Mercury. For example, scientists know that the concentration of iron in the core of Mercury is higher than that of any other planet. solar system. There are several possible explanations for this fact. The generally accepted theory is that the planet closest to the Sun originally had as much metals and silicates as ordinary meteorite. At the same time, the mass of Mercury was 2.25 times greater than now.

But at the very beginning of its existence, Mercury collided with a certain large body, as a result of which most of the crust and mantle separated from the planet. Accordingly, the relative proportion of the core of Mercury has increased. This theory looks somewhat dubious after the elemental composition of the surface of Mercury was studied by the Messenger probe.

As it turned out, Mercury is rich in potassium. But this element should not be abundant on a planet that has experienced a major impact. In the course of an impact sufficient to lose part of the crust and mantle, the planet should have become very hot, and the potassium would simply have evaporated. Now scientists are trying to explain this fact. In the meantime, they are looking for an explanation, another feature of the planet has become clear: it turns out that it is still geologically active.

Astronomers have studied the latest images of the Messenger probe. The images clearly show traces of recent tectonic processes. And this indicates that geological processes are still taking place on Mercury.

"Messenger" (Mercury Surface, Space ENvironment, GEochemistry and Ranging - MESSENGER) is an American automatic interplanetary station (AMS) for the study of Mercury. This probe transmitted to Earth a large amount of data about the planet closest to the Sun. Before "Messenger" it was investigated by another device - "Mariner-10". He flew near the planet in the 70s. Then they managed to get photographs of almost half of the surface of Mercury. True, scientists did not receive data on the chemical composition or structure of the planet - this apparatus was not equipped with the necessary instruments. The technology of that time did not yet allow the creation of relatively small probes with complex scientific instruments. In order to better study Mercury, NASA launched Messenger in 2004.

This device helped fill a number of gaps in the study of the planet. For example, in 2011 it turned out that the magnetic center is not located at all in the center of the planet, as, for example, the magnetic center of the Earth. It is displaced to the north, which causes deformation and magnetic field Mercury. In addition, Messenger found traces of volcanic activity. The presence of water ice in craters at the poles of the planet is also considered proven.

Thomas Watters of the Smithsonian Institution in Washington (USA) led the study of images of the planet, which were transmitted by Messenger just before its destruction. At the end of 2014, Messenger ran out of fuel, making it impossible to correct the orbit. Gradually, the periapsis began to shift lower and lower towards the surface of Mercury. On April 30, 2015, the Messenger completed its mission by crashing into the surface of the planet.

The photographs were able to consider the surface of Mercury in detail. In particular, scientists saw many faults that divide the flat regions of the planet into polygons. Previously, these faults were considered traces of the tectonic activity of the planet in its distant past. Planetologists believed that hundreds of millions of years ago, Mercury cooled down, its size decreased, and the surface was covered with irregularities.

Messenger probe during assembly (