Closest planets to mercury. Characteristics of the planet Mercury: description, structure, photo

The surface of Mercury, in short, resembles the Moon. Vast plains and many craters indicate that geological activity on the planet stopped billions of years ago.

Surface character

The surface of Mercury (photo is given later in the article), taken by the probes "Mariner-10" and "Messenger", outwardly looked like the moon. The planet is largely dotted with craters of various sizes. The smallest ones visible in the most detailed photographs of the Mariner measure several hundred meters in diameter. The space between the large craters is relatively flat and plain. It is similar to the surface of the Moon, but takes up much more space. Such regions surround Mercury's most visible impact structure from the collision, the Heat Plain Basin (Caloris Planitia). At the meeting with Mariner-10, only half of it was illuminated, and it was completely discovered by Messenger during its first flyby of the planet in January 2008.

Craters

The most common relief structures on the planet are craters. They largely cover the surface (photos are shown below), at first glance, they look like the Moon, but on closer examination they reveal interesting differences.

The gravity on Mercury is more than double that of the Moon, in part due to the high density of its huge core, made up of iron and sulfur. The strong force of gravity tends to keep the material ejected from the crater close to the collision site. Compared to the Moon, it fell at a distance of only 65% ​​of the lunar. This may be one of the factors that contributed to the emergence of secondary craters on the planet, formed under the influence of the ejected material, in contrast to the primary ones that arose directly during a collision with an asteroid or comet. More high strength of gravity means that complex shapes and structures characteristic of large craters - central peaks, steep slopes, and a flat base - on Mercury are observed in smaller craters ( minimum diameter about 10 km) than on the Moon (about 19 km). Structures smaller than this size have simple bowl-like outlines. The craters of Mercury are different from those of Mars, although the two planets have comparable gravity. Fresh craters on the first tend to be deeper than commensurate formations on the second. This could be due to the low volatiles content of Mercury's crust or higher impact velocities (since the speed of an object in solar orbit increases as it approaches the Sun).

Craters over 100 km in diameter begin to approach the oval shape typical of such large formations. These structures - polycyclic basins - are 300 km or more in size and are the result of the most powerful collisions. Several dozen of them were found on the photographed part of the planet. Messenger imagery and laser altimetry contributed greatly to understanding these residual scars from the early asteroid bombardments of Mercury.

Plain of Heat

This impact structure extends for 1550 km. When it was initially discovered by Mariner 10, it was believed that its size was much smaller. The interior of the facility is a smooth plain covered with folded and broken concentric circles. The largest ridges are several hundred kilometers long, about 3 kilometers wide and less than 300 meters high. More than 200 kinks, comparable in size to the edges, emanate from the center of the plain; many of them are depressions bounded by furrows (grabens). Where grabens intersect with ridges, they tend to pass through them, indicating their later formation.

Surface types

The Zhary plain is surrounded by two types of terrain - its edge and the relief formed by the discarded rock. The edge is a ring of irregular mountain blocks reaching 3 km in height, which are the most high mountains found on the planet, with relatively steep slopes towards the center. The second, much smaller ring is 100-150 km from the first. Behind the outer slopes there is a zone of linear radial ridges and valleys, partially filled with plains, some of which are dotted with numerous hillocks and hills several hundred meters in length. The origin of the formations that make up the wide rings around the Heat basin is controversial. Some of the plains on the Moon were formed mainly as a result of the interaction of ejections with pre-existing surface topography, and this may also be true for Mercury. But the results of "Messenger" suggest that volcanic activity played a significant role in their formation. Not only are there few craters compared to the Heat Basin, indicating a protracted period of plain formation, but they have other features more clearly associated with volcanism than could be seen in the Mariner 10 images. Critical evidence of volcanism came from the Messenger imagery showing the vents of volcanoes, many of which are located along the outer edge of the Zhara Plain.

Raditladi crater

Caloris is one of the youngest large polycyclic plains in at least the explored part of Mercury. It probably formed at the same time as the last giant structure on the Moon - about 3.9 billion years ago. Images of the Messenger revealed another, much smaller impact crater with a visible inner ring that may have formed much later, called the Raditladi Basin.

Strange antipode

On the other side of the planet, exactly 180 ° opposite the Plain of Heat, lies a patch of strangely distorted terrain. Scientists interpret this fact by talking about their simultaneous formation by focusing seismic waves from events that affected the antipodal surface of Mercury. The hilly and dotted terrain is a vast zone of hills, which are hilly polygons 5-10 km wide and up to 1.5 km high. The pre-existing craters were turned into hills and cracks by seismic processes, as a result of which this relief was formed. Some of them had a flat bottom, but then its shape changed, which indicates their later filling.

Plains

A plain is a relatively flat or smoothly wavy surface of Mercury, Venus, Earth and Mars, which is found everywhere on these planets. It is a "canvas" on which the landscape developed. The plains are evidence of the process of breaking down rough terrain and creating a smoothed space.

There are at least three ways of "polishing", due to which the surface of Mercury was probably leveled.

One way - increasing the temperature - reduces the strength of the bark and its ability to maintain high relief. Over the course of millions of years, the mountains "sink", the bottom of the craters will rise and the surface of Mercury is leveled.

The second method involves the movement of rocks towards lower areas of the terrain under the influence of gravity. Over time, rock accumulates in the lowlands and fills in higher levels as its volume increases. this is how lava flows from the bowels of the planet behave.

The third method consists in falling rock fragments onto the surface of Mercury from above, which ultimately leads to a leveling of the rough relief. Examples of this mechanism are rock outbursts from craters and volcanic ash.

Volcanic activity

Some evidence that lends itself to the hypothesis of the influence of volcanic activity on the formation of many of the plains surrounding the Zhara Basin has already been presented. Other relatively young plains on Mercury, especially visible in regions illuminated at low angles during the first flyby of the Messenger, exhibit characteristic volcanic features. For example, several old craters were filled to the brim with lava flows, similar to those on the Moon and Mars. However, the widespread plains on Mercury are more difficult to assess. As they are older, it is obvious that volcanoes and other volcanic formations may have been eroded or otherwise destroyed, making them difficult to explain. Understanding these old plains is important as they are likely responsible for the disappearance of most of the craters 10-30 km in diameter compared to the Moon.

Escarpas

The most important landforms of Mercury, which give an idea of ​​the internal structure of the planet, are hundreds of jagged ledges. The length of these rocks varies from tens to more than thousands of kilometers, and the height - from 100 m to 3 km. When viewed from above, their edges appear to be rounded or jagged. It is clear that this is the result of cracking, when part of the soil rose and lay on the adjacent terrain. On Earth, such structures are limited in volume and arise during local horizontal compression in the earth's crust. But the entire explored surface of Mercury is covered with scarps, which means that the planet's crust has decreased in the past. From the number and geometry of the scarps, it follows that the planet has decreased in diameter by 3 km.

In addition, shrinkage must have continued until relatively recent in geologic history, as some scarps have reshaped well-preserved (and therefore relatively young) impact craters. The deceleration of the initially high speed of rotation of the planet by tidal forces produced a contraction in the equatorial latitudes of Mercury. The globally distributed escarpments, however, suggest a different explanation: the late cooling of the mantle, possibly combined with the solidification of a portion of the once completely molten core, led to the compression of the core and deformation of the cold crust. The contraction of the size of Mercury as its mantle cools should have led to more longitudinal structures than can be seen, which indicates the incompleteness of the compression process.

The surface of Mercury: what is it made of?

Scientists have tried to figure out the composition of the planet by examining sunlight reflected from different parts of it. One of the differences between Mercury and the Moon, besides the fact that the former is slightly darker, is that its surface brightness spectrum is smaller. For example, the seas of the satellite of the Earth - smooth spaces visible to the naked eye as large dark spots - are much darker than the crater-riddled highlands, and the plains of Mercury are only slightly darker. Color differences are less pronounced on the planet, although the Messenger images taken with a set of color filters showed small, very colorful areas associated with the vents of volcanoes. These features, as well as the relatively inexpressive visible and near-infrared spectrum of reflected sunlight, suggest that the surface of Mercury consists of silicate minerals, poor in iron and titanium, which are darker in color compared to the lunar seas. In particular, the rocks of the planet may have a low content of iron oxides (FeO), and this leads to the assumption that it was formed under much more reducing conditions (i.e., with a lack of oxygen) than other members of the terrestrial group.

Remote research problems

It is very difficult to determine the composition of the planet by remote sensing of sunlight and the spectrum of thermal radiation that reflects the surface of Mercury. The planet is very hot, which changes the optical properties of the mineral particles and complicates direct interpretation. However, the Messenger was equipped with several instruments that were not aboard the Mariner 10, which directly measured the chemical and mineral composition. These instruments required a long observation period while the ship remained close to Mercury, so there were no concrete results after the first three short flights. Only during the orbital mission of "Messenger" there was enough new information about the composition of the planet's surface.

Of all the planets known today Solar system Mercury is the object of least interest to the scientific community. This is explained primarily by the fact that a small star burning dimly in the night sky, in fact, turned out to be the least suitable in terms of applied science. The first planet from the Sun is a lifeless space training ground, where nature itself was clearly trained in the process of the formation of the solar system.

In fact, Mercury can be safely called a real treasure of information for astrophysicists, from which you can glean a lot of interesting data on the laws of physics and thermodynamics. Using the information received about this most interesting celestial object, you can get an idea of ​​the effect that our star has on the entire solar system.

What is the first planet of the solar system?

Today, Mercury is considered the smallest planet in the system. Since Pluto was excluded from the list of the main celestial bodies of our near space and transferred to the category dwarf planets, Mercury took the honorable first place. However, this leadership did not add points. The place that Mercury occupies in the solar system leaves it out of sight modern science... It's all to blame, close location to the Sun.

This unenviable situation leaves an imprint on the behavior of the planet. Mercury at a speed of 48 km / s. rushes in its orbit, making a complete revolution around the Sun in 88 Earth days. It rotates around its own axis rather slowly - in 58.646 days, which gave astronomers a reason for a long time to consider Mercury turned to the Sun on one side.

With a high degree of probability, it is precisely this agility of the celestial body and its proximity to the central luminary of our solar system that became the reasons to give the planet a name in honor of the ancient Roman god Mercury, who was also distinguished by its swiftness.

To the credit of the first planet of the solar system, even the ancients considered it an independent celestial body that revolves around our star. From this angle, academic data about the closest neighbor of our star are curious.

Brief characteristics and features of the planet

Of all the eight planets in the solar system, Mercury has the most unusual orbit. Due to the insignificant distance of the planet from the Sun, it has the shortest orbit, but in its shape it is a highly elongated ellipse. Compared to the orbital path of other planets, the first planet has the highest eccentricity - 0.20 e. In other words, the motion of Mercury resembles a giant cosmic swing. At perihelion, the swift neighbor of the Sun approaches it at a distance of 46 million km, heating up to red. In aphelion, Mercury is given away from our star at a distance of 69.8 million km, having time to cool down a little in the vastness of space during this time.

In the night sky, the planet has a luminosity in a wide range from −1.9m to 5.5m, but its observation is very limited due to the close location of Mercury to the Sun.

This feature of orbital flight easily explains the wide range of temperature differences on the planet, which is the most significant in the solar system. However, the main hallmark astrophysical parameters of a small planet is the displacement of the orbit relative to the position of the sun. This process in physics is called precession, and what causes it is still a mystery. In the 19th century, a table of changes in the orbital characteristics of Mercury was even compiled, but it was not possible to fully explain this behavior of a celestial body. Already in the middle of the 20th, an assumption was made about the existence of a certain planet near the Sun, which affects the position of the orbit of Mercury. Confirm this theory at the moment technical means observation with a telescope is not possible due to the close location of the investigated area to the sun.

The most appropriate explanation for this feature of the planet's orbit is to consider precession from the point of view of Einstein's theory of relativity. Previously, the orbital resonance of Mercury was estimated as 1 to 1. In fact, it turned out that this parameter has a value of 3 to 2. The axis of the planet is located at right angles to the orbital plane, and the combination of the speed of rotation of the solar neighbor around its own axis with the orbital speed leads to a curious phenomenon ... The luminary, having reached the zenith, begins to reverse, therefore, on Mercury, the rising and setting of the Sun occur in one part of the Mercury horizon.

As for the physical parameters of the planet, they are as follows and look rather modest:

• the average radius of the planet Mercury is 2439.7 ± 1.0 km;
• the mass of the planet is 3.33022 · 1023 kg;
• the density of Mercury is 5.427 g / cm³;
• the acceleration of gravity at the Mercury equator is 3.7 m / s2.

The diameter of the smallest planet is 4879 km. Among the terrestrial planets, Mercury is inferior to all three. Venus and Earth are real giants compared to small Mercury, Mars is not much larger than the size of the first planet. The solar neighbor is inferior in size even to the moons of Jupiter and Saturn, Ganymede (5262 km) and Titan (5150 km).

The first planet of the solar system occupies a different position relative to the Earth. The closest distance between the two planets is 82 million km, while the maximum distance is 217 million km. If you fly from Earth to Mercury, then spaceship can reach the planet faster than going to Mars or Venus. This is due to the fact that a small planet is more often located closer to the Earth than its neighbors.

Mercury has a very high density, and by this parameter it is closer to our planet, surpassing Mars by almost two times - 5.427 g / cm3 versus 3.91 g / cm2 for the Red Planet. However, the acceleration of gravity for both planets, Mercury and Mars, is practically the same - 3.7 m / s2. For a long time, scientists believed that the first planet of the solar system was in the past a satellite of Venus, however, obtaining accurate data on the mass and density of the planet debunked this hypothesis. Mercury is a completely independent planet, formed during the formation of the solar system.

With its modest size, only 4879 kilometers, the planet is heavier than the Moon, and in terms of density it surpasses such huge celestial bodies as the Sun, Jupiter, Saturn, Uranus and Neptune combined. However, such a high density did not provide the planet with other outstanding physical parameters, neither in terms of geology, nor in terms of the state of the atmosphere.

Internal and external structure of Mercury

All terrestrial planets are characterized by a hard surface.

This is due to the similarity of the internal structure of these planets. In terms of geology, Mercury has three classical layers:

• the Mercurian crust, the thickness of which varies in the range of 100-300 km;
• a mantle, the thickness of which is 600 km;
• iron-nickel core 3500-3600 km in diameter.

The crust of Mercury is a kind of fish scales, where the layers of rocks formed as a result of the geological activity of the planet in the early periods were layered on top of each other. These layers have formed a kind of bulge, which are the features of the relief. The rapid cooling of the surface layer led to the fact that the crust began to shrink like pebbled skin, losing its strength. Later, with the end of the planet's geological activity, the Mercurian crust was subjected to strong external influences.

The mantle looks rather thin compared to the thickness of the crust, only 600 km. Such an insignificant thickness of the Mercury mantle speaks in favor of the theory according to which part of the planetary matter of Mercury was lost as a result of the collision of the planet with a large celestial body.

As for the core of the planet, there are many controversial points. The core diameter is ¾ the diameter of the entire planet and has a semi-liquid state. Moreover, in terms of the concentration of iron in the core, Mercury is the undisputed leader among the planets of the solar system. The activity of the liquid core continues to influence the surface of the planet, forming peculiar geological formations on it - swelling.

For a long time, astronomers and scientists about the surface of the planet had scanty ideas based on data from visual observations. Only in 1974, with the help of the American space probe "Mariner-10", mankind first had the opportunity to see the surface of its solar neighbor at close range. From the obtained images, it was possible to find out what the surface of the planet Mercury looks like. Judging by the images that were obtained thanks to "Mariner-10", the first planet from the Sun is covered with craters. The largest crater "Caloris" has a diameter of 1550 km. The areas between the craters are covered with Mercurian plains and rocky formations. In the absence of erosion, the surface of Mercury has remained almost the same as it was at the dawn of the formation of the solar system. This was facilitated by the early cessation of active tectonic activity on the planet. Changes in the Mercurian relief occurred only as a result of the fall of meteorites.

According to his colors Mercury strongly resembles the Moon, the same gray and faceless. The albedo of both celestial bodies is also almost the same, 0.1 and 0, 12, respectively.

Concerning climatic conditions on the planet Mercury, it is a harsh and cruel world. Despite the fact that under the influence of a nearby luminary, the planet heats up to 4500 C, heat is not retained on the Mercurian surface. On the shadow side of the planetary disk, the temperature drops to -1700C. The reason for such sharp temperature fluctuations is the extremely rarefied atmosphere of the planet. In physical parameters and in its density, the Mercurian atmosphere resembles a vacuum, however, even in such an environment, the planet's air layer consists of oxygen (42%), sodium and hydrogen (29% and 22%, respectively). Only 6% is helium. Less than 1% is accounted for by water vapor, carbon dioxide, nitrogen and inert gases.

It is believed that the dense air layer on the surface of Mercury disappeared as a result of a weak gravitational field planets and constant exposure to the solar wind. The close proximity of the Sun contributes to the presence of a weak magnetic field on the planet. In many ways, this proximity and the weakness of the gravitational field contributed to the fact that Mercury has no natural satellites.

Exploration of Mercury

Until 1974, the planet was mainly observed with optical instruments. With the beginning of the space age, mankind was able to begin a more intensive study of the first planet of the solar system. Only two terrestrial spacecraft managed to reach the orbit of the small planet - the American Mariner 10 and Messenger. The first flew three times past the planet during 1974-75, approaching Mercury as far as possible - 320 km.

Scientists had to wait for a long twenty years, until the NASA Messenger spacecraft went to Mercury in 2004. Three years later, in January 2008, the automatic interplanetary station made its first flyby of the planet. In 2011, the Messenger spacecraft safely took place in the planet's orbit and began to study it. Four years later, having worked out its resource, the probe fell to the surface of the planet.

The number of space probes sent to explore the first planet of the solar system, in comparison with the number of robotic vehicles sent to explore Mars, is extremely small. This is due to the fact that the launch of ships to Mercury is difficult from a technical point of view. To enter the Mercury orbit, it is necessary to perform a lot of complex orbital maneuvers, the implementation of which requires a large supply of fuel.

In the near future, it is planned to launch two space robotic probes at once, the European and Japanese space agencies. It is planned that the first probe will explore the surface of Mercury and its interior, while the second - the Japanese spacecraft - will study the atmosphere and magnetic field of the planet.

The first photo of MESSENGER from orbit of Mercury, with the bright Debussy crater visible at the top right. Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington.

Mercury characteristics

Weight: 0.3302 x 10 24 kg
Volume: 6.083 x 10 10 km 3
Average radius: 2439.7 km
Average diameter: 4879.4 km
Density: 5.427 g / cm 3
Escape velocity (second space velocity): 4.3 km / s
Gravity at surface: 3.7 m / s 2
Optical magnitude: -0.42
Natural satellites: 0
Rings? - Not
Semi-major axis: 57,910,000 km
Orbital period: 87.969 days
Perihelion: 46,000,000 km
Aphelios: 69,820,000 km
Average orbital speed: 47.87 km / s
Maximum orbital speed: 58.98 km / s
Minimum orbital speed: 38.86 km / s
Orbit inclination: 7.00 °
Orbital Eccentricity: 0.2056
Sidereal rotation period: 1407.6 hours
The length of a day: 4222.6 hours
Discovery: Known since prehistoric times
Minimum distance from Earth: 77,300,000 km
Maximum distance from Earth: 221,900,000 km
Maximum apparent diameter: 13 arc seconds
Minimum apparent diameter from Earth: 4.5 arc seconds
Maximum Optical Magnitude: -1.9

Mercury size

How big is Mercury? by surface area, volume and equatorial diameter. Surprisingly, she is also one of the densest. She acquired her title "smallest" after Pluto was demoted. This is why old records refer to Mercury as the second smallest planet. The above are the three criteria we will use to show.

Some scientists believe that Mercury is actually contracting. The liquid core of the planet occupies 42% of the volume. The planet's rotation allows a small portion of the core to be cooled. This cooling and contraction is believed to be evidenced by cracks in the planet's surface.

Much like, and the continued presence of these craters indicates that the planet has not been geologically active for billions of years. This knowledge is based on partial mapping of the planet (55%). It is unlikely to change even after MESSENGER maps the entire surface [ed. As of April 1, 2012]. The planet was most likely heavily bombarded by asteroids and comets during the Late Heavy Bombardment about 3.8 billion years ago. Some regions would be filled with magma eruptions from within the planet. These cratered smooth plains are similar to those found on the Moon. As the planet cooled, isolated cracks and ravines formed. These features can be seen on top of other features, which are a clear indication that they are new. Volcanic eruptions stopped on Mercury about 700-800 million years ago, when the planet's mantle compressed enough to obstruct lava flows.

The WAC photograph, showing a never-before-seen region of Mercury's surface, was captured about 450 km above Mercury. Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington.

Mercury diameter (and radius)

The diameter of Mercury is 4,879.4 km.

Need a way to compare it to something more similar? The diameter of Mercury is only 38% of the diameter of the Earth. In other words, you could place almost 3 Mercury side by side to match the diameter of the Earth.

In fact, there are some that have a larger diameter than Mercury. The largest moon in the solar system is Jupiter's moon Ganymede, with a diameter of 5.268 km, and the second largest moon, with a diameter of 5.152 km.

Earth's moon has a diameter of only 3.474 km, so Mercury is not much larger.

If you want to calculate the radius of Mercury, you need to halve the diameter. Since the diameter is 4,879.4 km, the radius of Mercury is 2,439.7 km.

Diameter of Mercury in kilometers: 4,879.4 km
Diameter of Mercury in miles: 3,031.9 miles
Radius of Mercury in kilometers: 2,439.7 km
Radius of Mercury in miles: 1,516.0 miles

Circumference of Mercury

The circumference of Mercury is 15.329 km. In other words, if the equator of Mercury were perfectly flat and you could drive a car, your odometer would add 15.329 km from your trip.

Most planets are spheroids compressed at the poles, so their equatorial circumference is greater than from pole to pole. The faster they rotate, the more the planet flattens, so the distance from the center of the planet to its poles is shorter than the distance from the center to the equator. But Mercury spins so slowly that its circumference doesn't depend on where you measure it.

You can calculate the circumference of Mercury yourself using classic mathematical formulas to get the circumference of a circle.

Circumference = 2 x Pi x radius

We know that the radius of Mercury is 2,439.7 km. So if you plug these numbers into: 2 x 3.1415926 x 2439.7, you get 15.329 km.

Circumference of Mercury in kilometers: 15,329 km
Circumference of Mercury in miles: 9.525 km

Crescent Moon of Mercury.

Volume of Mercury

The volume of Mercury is 6.083 x 10 10 km 3. The number seems to be huge, but mercury is the smallest planet in the solar system in terms of volume (since demotion to Pluto). It is even smaller than some of the moons in our solar system. The volume of Mercury is only 5.4% of the volume of the Earth, and the Sun is 240.5 million times the volume of mercury.

More than 40% of the volume of mercury is occupied by its core, to be exact 42%. The core has a diameter of about 3,600 km. This makes Mercury the second densest planet among our eight. The core is molten and mostly consists of iron. The molten core can produce a magnetic field that helps reflect the solar wind. The planet's magnetic field and negligible gravity maintains a negligible atmosphere.

Mercury is believed to have been a larger planet at one time; therefore, had a larger volume. There is one theory to explain its current size, which has been recognized by many scientists at several levels. The theory explains the density of mercury and the high percentage of matter in the core. The theory states that Mercury originally had a metal to silicate ratio similar to normal meteorites, as is the case with rocky matter in our solar system. At the time, the planet was believed to have a mass of about 2.25 its current mass, but early in the history of the solar system it was struck by a planetesimal that was 1/6 of its mass and several hundred kilometers in diameter. The impact scraped off much of the original crust and mantle, leaving the core as much of the planet and greatly shrinking the planet.

Volume of Mercury in cubic kilometers: 6.083 x 10 10 km 3.

Mass of Mercury
The mass of Mercury is only 5.5% of the earth's mass; actual value 3.30 x 10 23 kg. Since Mercury is the smallest planet in the solar system, you would expect it to be relatively small in mass. On the other hand, Mercury is the second densest planet in our solar system (after Earth). Given its size, the density comes primarily from the core, estimated at nearly half the planet's volume.

The mass of the planet consists of substances that are 70% metallic and 30% silicate. There are several theories to explain why the planet is so dense and rich in metallic substances. Most of the widely supported theories support that a high percentage of the core is the result of impact. In this theory, the planet originally had a metal to silicate ratio similar to the chondrite meteorites common in our solar system and 2.25 times its current mass. Early in the history of our universe, Mercury hit a planetesimal-sized object that was 1/6 of the hypothetical mass of Mercury and hundreds of kilometers in diameter. A blow of such force would have scraped off much of the crust and mantle, leaving a huge core. Scientists believe a similar incident created our moon. An additional theory says the planet formed before the sun's energy was stabilized. The planet had a much higher mass in this theory, but the temperatures created by the protosun would be very high, around 10,000 Kelvin, and most of the rock on the surface would be vaporized. The stone vapor might then be carried away by the solar wind.

Mass of Mercury in kilograms: 0.3302 x 10 24 kg
Mass of Mercury in pounds: 7.2796639 x 10 23 lb
Mass of Mercury in metric tons: 3.30200 x 10 20 tons
Mass of Mercury in tons: 3.63983195 x 10 20

Artistic concept of MESSENGER in orbit around Mercury. Credit: NASA

Gravity of Mercury

The gravity of Mercury is 38% of Earth's gravity. A person weighing 980 Newtons on Earth (about 220 pounds) would only weigh 372 Newtons (83.6 pounds) if they landed on the planet's surface. Mercury is only slightly larger than our Moon, so you can expect gravity to be similar to the Moon's 16% of Earth's. The big difference is the higher density of Mercury - it is the second densest planet in the Solar System. In fact, if Mercury were the same size as Earth, it would be even denser than our own planet.

It is important to clarify the difference between mass and weight. Mass is measured by how much substance something contains. Therefore, if you have 100 kg of mass on Earth, you have the same amount on Mars, or in intergalactic space. Weight, however, is the force of gravity that you feel. Although bathroom scales are measured in pounds or kilograms, they really should be measured in newtons, which are a measure of weight.

Take your current weight in either pounds or kilograms and then multiply by 0.38 on a calculator. For example, if you weigh 150 pounds, you would weigh 57 pounds on Mercury. If you weigh 68 kg on a bathroom scale, your weight on Mercury would be 25.8 kg.

You can also flip this number over to figure out how much stronger you would be. For example, how high you could jump, or how much weight you could lift. The current world record for high jumping is 2.43 meters. Divide 2.43 by 0.38 and you would have a world high jump record if it were achieved on Mercury. In this case, it would be 6.4 meters.

In order to avoid the gravity of Mercury, you need to move at a speed of 4.3 km / s, or about 15.480 km / h. Let us compare this with the Earth, where the escape velocity (second cosmic velocity) of our planet is 11.2 km / s. If you compare the ratio between the two planets, you get 38%.

Gravity on the surface of Mercury: 3.7 m / s 2
Escape velocity (second space velocity) of Mercury: 4.3 km / s

Density of Mercury

The density of Mercury is the second largest in the Solar System. Earth is the only denser planet. It is equal to 5.427 g / cm 3 compared to the earth's density of 5.515 g / cm 3. If gravitational contraction were removed from the equation, Mercury would be denser. The high density of the planet is a sign of a large percentage of the core. The core makes up 42% of the total volume of Mercury.

Mercury is a terrestrial planet like Earth, only one of four in our Solar System. Mercury has about 70% metallic substances and 30% silicates. Add the density of Mercury and scientists can deduce the details of its internal structure. While the high density of the Earth is largely responsible for the gravitational contraction in its core, Mercury is much smaller and less compressed internally. These facts have led NASA scientists and others to speculate that its core must be large and contain crushing amounts of iron. Planetary geologists estimate that the molten core of the planet accounts for about 42% of its volume. On Earth, the core is 17%.

Internal structure of Mercury.

This leaves the silicate mantle only 500-700 kkm thick. Data from Mariner 10 led scientists to believe that the crust is even thinner, on the order of 100-300 km. The mantle surrounds the core, which has a higher iron content than any other planet in the solar system. So what caused this disproportionate amount of core material? Most scientists accept the theory that Mercury had a metal to silicate ratio similar to normal meteorites - chondrites - several billion years ago. They also believe that it had a mass of 2.25 times its current mass; however, Mercury may have struck a planetesimal 1/6 the mass of Mercury and hundreds of kilometers in diameter. The impact would scrape off much of the original crust and mantle, leaving a larger percentage of the planet to the core.

While scientists have several facts about the density of Mercury, there are still more to be discovered. Mariner 10 sent back a lot of information, but was only able to study 44% of the planet's surface. fills in the blanks on the map as you read this article, and the BepiColumbo mission goes further in expanding our knowledge of this planet. Soon, more theories will emerge to explain the planet's high density.

Density of Mercury in grams per cubic centimeter: 5.427 g / cm 3.

Axis of mercury

Like all planets in the Solar System, Mercury's axis is tilted from. In this case, the axial tilt is 2.11 degrees.

What is the exact axial tilt of the planet? First, imagine the Sun is a ball in the middle of a flat disc, like a vinyl record or CD. The planets are in orbit around the Sun within this disk (more or less). This disc is known as the ecliptic plane. Each planet also rotates on its own axis when in orbit around the Sun. If the planet rotated perfectly straight up and down, then this line running through the north and south poles of the planet would be perfectly parallel with the poles of the sun, the planet would have an axial tilt of 0 degrees. Of course, none of the planets has such a tilt.

Therefore, if you were to draw a line between the north and south poles of Mercury and compare it with an imaginary line, Mercury would not have an axial tilt at all, this angle would be 2.11 degrees. You might be surprised to learn that the tilt of Mercury is the smallest of all the planets in the Solar System. For example, the tilt of the Earth is 23.4 degrees. And Uranus is generally inverted on its axis and rotates with an axial tilt of 97.8 degrees.

Here on Earth, the axial tilt of our planet is causing the seasons. When it's summer in the northern hemisphere North Pole deflected outward. You get more sunshine in the summer, so it's warmer, and less in the winter.

Mercury does not experience any seasons. Due to the fact that it has almost no axial tilt. Of course, it does not have a large atmosphere to keep warm from the Sun. Any side facing the Sun warms up to 700 degrees Kelvin, and the side facing the Sun has temperatures below 100 Kelvin.

Axial tilt of Mercury: 2.11 °.

Mercury is similar in physical characteristics to the Moon. It has no natural satellites, its atmosphere is very rarefied. This planet has a large iron core, accounting for 83% of the volume of the entire planet. This core is the source of a magnetic field with an intensity of 0.01 of the earth's. The planet's surface temperature is - 90 - 700 K (-183.15-426.85 C). The solar side of the planet heats up significantly more than its reverse side and polar regions.

Mercury craters

On the surface of Mercury is located a large number of craters, the landscape is very similar to the lunar. In different parts of Mercury, the density of craters is different. It is possible that the areas of the planet's surface that are more heavily dotted with craters are older, and those that are less dotted with younger ones. They were formed as a result of the flooding of the old surface with lava. Moreover, there are fewer large craters on Mercury than on the Moon. The largest crater on Mercury has a diameter of 716 km and was named after Rembrandt, the great Dutch painter. Also, there are formations on Mercury, the likes of which are not on the Moon. For example, scarps are numerous jagged slopes that extend for hundreds of kilometers. When studying the scarps, it was found that they were formed during the compression of the surface, accompanying the cooling of Mercury, in which the surface area of ​​the planet decreased by 1%. Because there are well-preserved large craters on the surface of Mercury, which means that over the past 3-4 billion years there has been no movement of parts of the crust on a large scale, there has been no erosion on the surface (by the way, the latter almost completely confirms the impossibility of the existence of any any significant atmosphere).

During the research, the Messenger probe obtained photographs of more than 80% of the planet's surface, as a result of which it was determined that it is homogeneous, in contrast to the surface of Mars or the Moon, in which one hemisphere is very different from the other.
The elemental composition of the surface of Mercury, obtained by the X-ray fluorescence spectrometer of the Messenger apparatus, showed that the planet's surface is rich in plagioclase feldspar, characteristic of the continental regions of the Moon, and, in comparison, is poor in calcium and aluminum. It is also rich in magnesium and poor in iron and titanium, which allows it to occupy the gap between ultrabasic rocks, like terrestrial komatiites, and typical basalts. A relative abundance of sulfur has also been discovered, which means that the planet was formed under reducing conditions.
The craters of Mercury differ from each other. They can be small bowl-shaped depressions, and impact multi-ring craters, which are hundreds of kilometers in diameter. The craters of Mercury have been destroyed to varying degrees. There are more or less well-preserved ones, with long beams located around them, formed in the process of ejection of matter from the impact of the impact. There are also very destroyed remains of craters.
The Plain of Heat (Latin Caloris Planitia) is one of the most prominent features of the relief of Mercury. It is so named because it is located near one of the "hot longitudes". The diameter of this plain is about 1550 km.
Most likely, the body, the collision of which with the surface of Mercury formed a crater, was at least 100 km in diameter. The impact was so strong that seismic waves, passing through the entire planet and gathering at the opposite point on the surface, caused the formation of a kind of "chaotic" rugged landscape on Mercury. The force of the blow is also evidenced by the fact that it provoked the ejection of lava, as a result of which the mountains of Zhary, more than 2 km high, were formed around the crater. Kuiper Crater (60 km across) is the point on the planet's surface with the highest albedo. Most likely, the Kuiper crater is one of the "last" large craters of Mercury formed.
Another interesting arrangement of craters on the planet was discovered by scientists in 2012: the sequence of the arrangement of craters forms the face of Mickey Mouse. Maybe in the future this configuration will be named that way.

Geology of Mercury

More recently, it was believed that in the bowels of Mercury there is a metal core, the radius of which
rogo 1800 - 1900 km, it is 60% of the mass of the planet, since a weak magnetic field was detected by the spacecraft "Mariner-10". In addition, according to scientists, it was believed that the core of Mercury, due to the small size of the planet, should not be liquid. After five years of radar observations, the team of Jean-Luc Margot summed up the results in 2007, and as a result, various variations in the rotation of Mercury were noted, which are too large for a planet with a solid core. Based on this, we can say with almost one hundred percent accuracy that the core of Mercury is liquid.

Compared to any planet in the solar system, the percentage of iron in the core of Mercury is higher. There are several versions of this explanation. The most widespread theory in the world of science says that Mercury, originally having a mass of 2.25 times that of today, had the same proportion of silicates and metal as an ordinary meteorite. But at the very beginning of the history of the solar system, a planet-like body, several hundred kilometers in diameter, and a mass 6 times less, collided with Mercury. Because of this collision, most of the primary crust and mantle were torn off the planet, as a result of which the relative fraction of the core in Mercury increased. By the way, to explain the formation of the moon, a similar hypothesis was proposed, called the Giant Collision Theory. But this theory is contradicted by the first data that were obtained in the process of studying the elemental composition of the surface of Mercury using the AMS Messenger gamma-spectrometer (it allows you to measure the content of radioactive isotopes). It turned out that there is a lot of potassium on the planet (a volatile element when compared with thorium and uranium, which are more refractory). This is inconsistent with the high temperatures inevitable in a collision. Based on this, it becomes clear that the elemental composition of Mercury coincides with the primary elemental composition of the material that formed it, which is close to anhydrous cometary particles and enstatite chondrites, while the iron content in the latter, today, is small to explain the high average density of the planet.
A silicate mantle (500-600 km thick) surrounds the core of Mercury. The thickness of its crust is in the range of 100 - 300 km (according to "Mariner-10").

Geological history of Mercury

The geological history of the planet is divided into eras, like those of Mars, the Moon and the Earth. These eras are called as follows (to the later from the earlier): 1- pre-Tolstoy, 2- Tolstoy, 3- Kalor, 4- late Kalor, 5- Mansur and 6- koiper. And the relative geological age of Mercury is divided into periods according to the given eras. True, the absolute age measured in years has not been precisely established.
About 4.6 billion years ago, when the planet was already formed, there was an intense collision with comets and asteroids. The last massive bombing of Mercury was 3.8 billion years ago. Some areas (for example, the Plain of Zhara) were created, among other things, by filling them with lava. As a result, smooth lunar-like cavities formed inside the craters.
After that, as Mercury cooled and contracted, faults and ridges were formed. The later time of their formation is evidenced by their location on the surface of large relief objects, for example, plains and craters. The time of volcanism on the planet ended after the mantle contracted enough to prevent the release of lava to the surface of Mercury. It is possible that this happened during the first 700-800 million years after the formation of Mercury. Later changes in the planet's landscape were caused by impacts of cosmic bodies on its surface.

Mercury's magnetic field

The strength of the magnetic field of Mercury is approximately one hundred times less than that of the Earth and is equal to ~ 300 nT. The Mercury magnetic field has a dipole structure, is very symmetrical, its axis is only 10 degrees away from the axis of rotation of Mercury. This significantly reduces the number of hypotheses explaining the origin of the magnetic field of Mercury. It is assumed that the magnetic field of Mercury arises due to the dynamo effect (the same happens on Earth). Perhaps this effect is a consequence of the circulation of the liquid core. A very strong tidal effect arises from the very pronounced eccentricity of Mercury. This tidal effect keeps the core in a liquid state, which is a prerequisite for the dynamo effect to occur. The planet's magnetic field is so strong that it can change the direction of the solar wind around Mercury, as a result of which its magnetosphere is created. And although it is so small that it would fit inside the Earth, it is powerful enough to catch the plasma of the solar wind. As a result of observations obtained with the help of "Mariner-10", it turned out that there is a low-energy plasma in the magnetosphere of the night side of Mercury. Explosions of active particles in the tail of the magnetosphere indicate its inherent dynamic properties.

On October 6, 2008, the Messenger, flying over Mercury for the second time, recorded a large number of windows in the planet's magnetic field. Messenger discovered the phenomenon of magnetic vortices. These are the interlaced knots of the magnetic field that connect the spacecraft to the magnetic field of Mercury. The diameter of the vortex was 800 km, which is one third of the planet's radius. The solar wind creates such a vortex form of the magnetic field. As the solar wind flows around the magnetic field of Mercury, it binds and rushes with it, forming into vortex-like structures. Such vortices create windows in the magnetic shield of the planet, through which the solar wind penetrates, reaching the surface of the planet. The connection between the interplanetary and planetary magnetic fields (magnetic reconnection) is a common cosmic phenomenon that occurs around the Earth, at the time when it creates magnetic vortices. But the frequency of the magnetic reconnection of Mercury, according to the Messenger, is 10 times higher.

Characteristics of the planet:

• Distance from the Sun: 57.9 million km
• Planet diameter: 4878 km
• Day on the planet: 58 days 16 h.*
• Year on the planet: 88 days*
• t ° on the surface: -180 ° C to + 430 ° C
• Atmosphere: almost not present
• Satellites: does not have

* period of rotation around its own axis (in earth days)
** orbital period around the Sun (in Earth days)

Mercury is the eighth largest planet closest to the Sun, with an average distance of 0.387 AU (astronomical units) or 57,910,000 kilometers. The planet's mass is 3.30e23 kg, and its diameter is 4.880 km (only Pluto is smaller).

Presentation: Planet Mercury

Internal structure

In the center of the planet there is a metal core, similar to that of the earth, the difference is only in size. If the earth's core occupies only 17% of the planet's volume, then Mercury has 42% of the volume.

Around the core is a layer of mantle - 500-700 kilometers of silicate rock. The next layer is the crust, which is about 100-300 kilometers thick. Upper layer the planet has a lot of damage, most scientists adhere to the theory that they arose due to the slow cooling of Mercury.

Atmosphere and surface

The atmosphere of Mercury is very rarefied and practically equates to a vacuum. Compound:

• hydrogen (70 atoms per 1 cm³);
• helium (4,500 atoms per 1 cm³).

Due to the practically zero atmosphere and proximity to the Sun, the temperature on the planet's surface fluctuates between -180 .... + 440 ° C. The surface resembles the lunar - many craters (from collisions with asteroids), and mountains up to 4 km high (the lunar can be one and a half times higher).

Unlike the Earth satellite, on back side Mercury is located swelling, which formed under the influence of solar tides. There are also high ledges, the length of which can reach several hundred kilometers.

The name of the planet was given by the ancient Romans, who worshiped the god Mercury as the patron saint of thieves, travelers and merchants. However, it is believed that the first planet from the Sun was known as early as 3000 years BC. (since the time of the Samaritans).

V Ancient Greece she was called by two names at once - Apollo (god of sunlight, patron of arts and science) in the morning and Hermes (smart messenger of the gods) in the evening. Moreover, the Greeks did not know that they were seeing the same planet.

For a long time, astronomers could not understand the motion of Mercury across the sky, and all because of the anomalous precession of its orbit. Newtonian mechanics did not fit in any way to explain the too elongated orbit: perihelion = 46 million km from the Sun, aphelion = 70 million km. Scientists of the 19th century even believed that some other planet (sometimes called Vulcan) was moving close to Mercury, which affects its orbit. It became possible to correctly predict the movement of the planet only after Einstein discovered it. General Theory Relativity.

Exploring the planet

The study of Mercury is very difficult due to its close location to the Sun. It is impossible to obtain high-quality images from the American Hubble Telescope.

Only one interplanetary station approached the planet - Mariner 10, which made three flights in 1974-1975. Only 45% of the planet was mapped.

Radar observations were also carried out, but these data are more likely to be theoretical than hard facts. So, a similar study showed the presence of frozen water at the north pole of Mercury (Mariner did not map this area).