Mercury or the moon, whichever is larger. Which celestial body is larger - the Moon or Mercury? Why might these celestial bodies be useful to earthlings? Educational and interesting facts about the planet Mercury

The planet Mercury is similar to the Moon. The surface of this ancient planet is pitted with craters, like many satellites of other planets. Mercury is larger than almost all the moons of other planets, but smaller than Ganymede (a moon of Jupiter) and Titan (a moon of Saturn). Compared to the satellites of other planets, Mercury is much denser and more massive, as it consists mainly of iron.

The planet Mercury is very similar to a satellite. The old surface of Mercury is densely dotted with craters, like most planetary satellites. Mercury is larger than many moons and yet smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is significantly denser and more massive than almost any moon because it is made primarily of iron. And only the Earth, the only planet, is denser than Mercury.

The planet closest to the Sun, Mercury, remains the most mysterious among the inner planets of the Solar System. Hidden in the Sun's rays, Mercury is a difficult object to observe from Earth. The only spacecraft to study Mercury at close range was Mariner 10, which made two flybys of Mercury in 1974 and 1975, examining about 45 percent of the planet's surface.

The planet Mercury has been known since the beginning of recorded history, but parts of this innermost planet in the solar system have never been seen. Two days ago, the robotic Messenger spacecraft flew by Mercury for the second time and photographed areas that had previously been crudely mapped only by radar.

Mercury is one of the smallest planets in size. solar system, which is also located at the closest distance from the Sun. The Moon is a celestial body that is located relatively close to the Earth. In total, in the entire history of mankind, 12 people have visited the Moon. Up flies for six months. Today it takes only three days to get to the moon. Why are both of these celestial bodies interesting for astronomers and other scientists?

Why do earthlings need the Moon and Mercury?

The most frequently asked question regarding them is: “Which celestial body is larger - the Moon or Mercury?” Why does this mean so much to scientists? The fact is that Mercury is the closest candidate for colonization. Like the Moon, Mercury is not surrounded by an atmosphere. A day here lasts a very long time and amounts to as much as 59 Earth days.

The planet rotates around its axis very slowly. But not only the question of which celestial body is larger - the Moon or Mercury - is of interest to scientists in connection with possible colonization. The fact is that the exploration of Mercury may be hampered by its proximity to the main luminary of our system. But scientists suggest that there may be ice caps at the planet's poles that could facilitate the colonization process.

The closest planet to the Sun

On the other hand, close proximity to the star can guarantee a constant supply of solar energy, if scientists still manage to colonize the planet and build energy stations on it. Researchers believe that due to Mercury's slight tilt, there may be areas called "peaks of eternal light" on its territory. They are of main interest to scientists. Mercury's soil contains large deposits of ore that can be used to create space stations. And also its soils are rich in the element Helium-3, which could also become a source of inexhaustible energy.

Difficulties in studying Mercury

Mercury has always been very difficult for astronomers to study. Primarily due to the fact that the planet is obscured by the bright rays of the system’s main star. That is why scientists for a very long time could not determine which celestial body is larger - the Moon or Mercury. A planet rotating in the vicinity of the Sun always turns out to be facing the same side towards the star. Despite this, in the past scientists have tried to map reverse side Mercury. But she was not very popular, and she was treated with skepticism. For a very long time it was extremely difficult to determine which celestial body was larger - the Moon or Mercury. Photos of these planets allowed us to conclude that they were approximately the same.

and Mercury

Some of the first astronomical discoveries were the discovery of craters on Mars and the Moon. Then scientists expected that there would be plenty of them on Mercury. After all, this planet is located between the Moon and Mars in size. Moon or Mercury - which is larger and what does this have to do with craters? All this became known after an interplanetary station called Mariner 10 flew around Mercury twice. She took a huge number of photographs, and also compiled detailed maps Mercury. Now there was as much knowledge about the planet as there was about the Earth’s satellite.

It turned out that there are as many craters on the territory of Mercury as on the Moon. And a surface of this kind had exactly the same origin - countless meteorite showers and powerful volcanoes. Even a scientist could not distinguish the surface of Mercury from the surface of the Earth's satellite from photographs.

Meteorite pits on these celestial bodies are formed due to the lack of an atmosphere that could soften impacts from the outside. Previously, scientists believed that Mercury still has an atmosphere, only a very rarefied one. The planet's gravity cannot maintain an atmosphere on its surface that could be similar to Earth's. But still, the instruments of the Mariner 10 station showed that the concentration of gases near the surface of the planet is greater than in space.

Is it possible

The first obstacle that stands in the way of those who dream of populating the Earth's satellite is its constant susceptibility to meteorite bombardment. Meteorite attacks, as scientists have found, occur a hundred times more often than previously thought. Various changes are constantly occurring on the surface of the Moon. Meteorite craters can range in diameter from a few centimeters to 40 meters.

However, in 2014, Roscosmos made a statement that by 2030 Russia would begin a program for mining minerals on the Moon. With regard to such programs, the question of which celestial body is larger - the Moon or Mercury - fades into the background. After all, so far this statement has been made only in relation to the Earth’s satellite. Russia has no plans to colonize Mercury yet. Plans for production were announced on Cosmonautics Day in 2014. For this purpose, the RAS is already developing a scientific program.

Moon or Mercury - which is larger and which planet is more advantageous for colonization?

On Mercury the temperature is about 430 °C. And it can drop to -180 °C. At night, the temperature on the surface of the Earth’s satellite also drops to -153 °C, and during the day it can reach +120 °C. In this regard, these planets are still equally unsuitable for colonization. Which celestial body is larger - the Moon or Mercury? The answer will be as follows: the planet is still larger. Mercury is larger than the Moon in size. The diameter of the Moon is 3474 km, and the diameter of Mercury is 4879 km. Therefore, for now, dreams of settling beyond the Earth remain a fantasy for humanity.

In the "neighborhood" of the Sun, flooded with dazzling streams bright light, the planet Mercury is moving. The apparent angular distance of the planet from the central star never exceeds 28 degrees, making Mercury very difficult to observe. Most of the time it is literally buried in the rays of the daylight and only briefly appears against the background of the golden morning dawn or in the glow of the evening sunset.

All observers, starting with the famous Italian astronomer Giovanni Schiaparelli, who studied Mercury in late XIX centuries, invariably pointed to one feature: the planet rotates around its axis and orbits the Sun in the same period of time, equal to 88 Earth days. This would seem to be evidenced by sketches of the location of spots on the planetary disk. It turned out that Mercury always faces the Sun with one side. And if so, then on one hemisphere there should be eternal day, and on the other - eternal night. Scientists explained the synchronicity of the planet’s rotation by tidal braking of the Sun, and as a clear example pointed to the Moon, one side facing the Earth.

In the second half of the 20th century, the idea of ​​the nature of Mercury's rotation had to be completely revised. This was facilitated by the rapid development of radiophysical research methods. Accurate data on the planet's rotation were obtained by analyzing radar sessions.

In 1965, American astronomers using a giant 305-meter radio telescope in Arecibo (Puerto Rico) radar method determined the period of Mercury's axial rotation to be 2/3 of the orbital duration. In Earth solar days this is 58.6457. This is actually the period of rotation of Mercury around its own axis in relation to distant stars. Therefore, there can be neither eternal day nor eternal night on Mercury. At this rotation speed alone sunny day there are equal to almost 176 (175.9371) Earth days, or two Mercury years (87.96855 2 = 175.9371). In other words, the days and nights on Mercury last for an entire year! At perihelion - the point in the orbit closest to the Sun - the middle of Mercury's illuminated hemisphere heats up to 467°C. And on the night side there is freezing cold: the temperature can drop to -183°C.

In the family of major planets, Mercury is rather modest in size. Its diameter is 2.61 times smaller than the diameter of the Earth. Therefore, the planet is smaller in volume globe 17.8 times (2.61·2.61·2.61 = 17.8). At the same time, the planet is 18.1 times less massive than Earth. It turns out that the average density of Mercury is almost equal to that of the Earth - it is 5.43 g/cm 3 (for the Earth it is 5.52 g/cm 3). And this is at a time when the planet’s interior is not experiencing strong compression! Thus, after our Earth, Mercury is the densest planet.

Some researchers believe that Mercury is a unique mine planet, which by mass is 60% iron. Its massive iron core is surrounded by a relatively thin silicate shell with powerful branched ore-bearing veins that extend directly to the surface. It is quite possible that during the day on the surface of Mercury, incinerated by fiery breath close Sun, “lakes” of molten metals (tin, lead, zinc) are formed, similar to erupted volcanic lava.

The American Mariner 10 spacecraft (1974) transmitted to Earth about 3000 images of the planet's surface with a resolution of up to 50 m.

Comparing images of Mercury with images of the Moon shows their great similarity. The surface of Mercury is also covered with many impact craters, and the Mercury landscape can easily be confused with the lunar one. But upon careful study of the images, you can find differences: large craters are found less often on Mercury than on the Moon. The largest crater on Mercury is named after the great German composer Beethoven. Its diameter reaches 625 km!

The next important difference between the mountainous landscapes of Mercury and the Moon is the presence of numerous jagged slopes on Mercury, extending for hundreds of kilometers. The study of their structure showed that they were formed in the early period of the planet’s development as a result of global compression of the crust. The presence of well-preserved large craters on the surface of Mercury suggests that over the past 3-4 billion years there has been no large-scale movement of sections of the crust, and there has been no surface erosion. The latter circumstance almost completely excludes the existence of any significant atmosphere in the history of Mercury.

Photographs of the surface of Mercury also show several relatively smooth large plains, which are obviously much younger than the heavily cratered areas. The most extensive plain is the Sea of ​​Heat, or the Sea of ​​Heat, reaching 1300 km in diameter; it is located in the equatorial zone of the planet. You look at it and involuntarily remember the lunar Sea of ​​Rains. Both arose as a result of gigantic disasters - collisions with asteroid bodies.

Using a sensitive magnetometer installed on Mariner 10, a dipole magnetic field was discovered near Mercury, directed approximately along the planet's rotation axis. But the intensity of this field on the surface of Mercury does not reach even 1% of the intensity magnetic field Earth. However, Mercury's magnetic field is much stronger than that of Venus or Mars.

Apparently, there are necessary conditions for its generation inside the planet.

Thus, as a result space research It was found that Mercury is a paradox planet: externally and in terms of the history of surface formation, it is similar to the Moon, and in its internal structure it reveals a surprising similarity to the Earth. Even Mercury's magnetic field is similar to Earth's.

The closest planet to the Sun is only slightly larger than the Moon: its

the radius is 2439 km. However, its average density (5.45 g/cm3) is noticeably higher,

than that of the Moon, it is almost the same as that of the Earth. Acceleration of gravity by

surface 372 cm/sec2, 2.6 times less than on Earth. Orbital period

The sun is about 88 Earth days. Due to the small angular dimensions (about 7"

at greatest elongation) and proximity to the Sun Mercury (163) observe

difficult, and little data has been obtained about this planet.

Mercury's radar made it possible to determine the direction and period of rotation

planets. In these experiments, Mercury was irradiated for long periods of time, almost

monochromatic pulses of radio waves 70 cm long using a giant

antennas with a diameter of 300 m (Puerto Rico, Arecibo radio astronomy observatory;

see 103). The reflected pulse due to the Doppler effect is blurred along

frequency if the planet rotates. The rotation visible from the Earth consists of

actual axial rotation and rotation caused by orbital motion.

By conducting radar at different positions of the planet in orbit, it is possible

determine both the speed and direction of axial rotation. Radar

Mercury at a wavelength of 70 cm showed that its rotation is direct, with

period 58.6 ±0.5 days. This is close to 2/3 of the planet's orbital period. Axis

rotation is approximately perpendicular to the ecliptic plane.

Experienced observers distinguish more or less stable

details. Analysis of visual sketches and photographs shows that those observed on

their repetitions can be explained by periods of rotation

where T is the period of revolution around the Sun. The third of these values ​​within

errors coincides with the radar period. Based on observations of details on the disk

the ratio t/T = 2/3 is maintained with an accuracy of no less than 0.01 Earth days.

It is easy to see that with such a ratio of periods, the Mercury solar

a day (the interval from one sunrise to another) should last twice as long

Mercury year!

Until recently, there was a widespread belief that the periods of rotation and revolution

Mercury are equal and Mercury always faces the Sun with the same side.

The reason is clear: from a series of numbers (10.7) only the first was chosen, the rest

were dismissed as unlikely. Radar showed the error of this point

The American spacecraft Mariner 10 transmitted phototelevision

images of Mercury with approximately the same degree of detail as obtained

when studying the Moon with ground-based telescopes. Direct flight of the spacecraft from

Earth to Mercury requires a lot of energy. This difficulty can be overcome by

go to Mercury. It was in this orbit that Mariner 10 flew to Mercury. On

164 shows a “mosaic” image of Mercury obtained using

television cameras "Marinera-10". The surface of Mercury is very similar to the moon.

The first thing that catches your eye is big number craters of various types

sizes. However, there are also differences. Mercury does not have extensive marine areas,

relatively smooth and more free from craters. On the other hand, on

on the surface of Mercury there are such formations as very high (several

kilometers) ledges that stretch over distances of thousands of kilometers. They

indicate that the planet contracted during its evolution.

164. “Mosaic” (composed of many individual images) photography

Mercury, obtained using the Mariner 10 television cameras.

The similarity of the Moon and Mercury is also indicated by the similarity of their photometric and

polarimetric characteristics: dependence of magnitude and polarization on

phases, surface reflectivity. Like on the Moon, very large

differences in surface temperature measured by infrared radiation. IN

at noon at the equator the maximum temperature reaches 700 °K, and at night

side drops to 100°K. At the same time, the intensity of thermal radio emission

The centimeter range on the night and day sides differs little.

Consequently, the surface layer of soil on Mercury, as well as on the Moon,

is a finely crushed rock with a relatively low density

(regolith).

The atmosphere of Mercury has an extremely low density - the concentration is no more than 106

cm -3 at the surface. This concentration of gas in the earth's atmosphere is found at

altitude 700 km. The composition of the atmosphere is not precisely known;

spectroscopic measurements

helium was discovered on Mariner 10 (concentration about 104 cm -3), but

Apparently there must be other gases as well.

Mercury has its own magnetic field. Its intensity near the surface

at the equator there is about 0.002 oe (300 times less than on Earth).

Magnetic dipole axis

approximately coincides with the axis of rotation.
Mercury has no satellites.

What is the surface area

The surface area is 75 million square kilometers, which is approximately 10% of the Earth's surface area.

If you could unfold Mercury, it would become almost twice the size of Asia (44 million square kilometers).

What about volume? The volume is 6.1 x 10*10 km3. This is a large number, but it is only 5.4% of the Earth's volume. In other words, we could put 18 Mercury-sized objects inside the Earth.

Weight is 3.3 x 10*23 kg. Again, this is a lot, but in terms of ratio it is only equal to 5.5% of the mass of our planet.

Finally, let's look at the force of gravity on its surface. If you could stand on the surface of Mercury (in a good, heat-resistant spacesuit), you would feel 38% of the gravity you feel on Earth. In other words, if you weigh 100 kg, then on Mercury there are only 38 kg.