How long is the planetary year on mercury. How long is a day on Mercury? History and name
Mercury is the planet closest to the Sun. There is practically no atmosphere on Mercury, the sky there is as dark as night and the Sun always shines brightly. From the surface of the planet, the Sun would appear 3 times larger than Earth's. Therefore, temperature drops on Mercury are very pronounced: from -180 o C at night to unbearably hot +430 o C during the day (at this temperature, lead and tin melt).
This planet has a very strange timing. On Mercury, you will have to adjust the clock so that a day lasts approximately 6 Earth months, and a year only 3 (88 Earth days). Although the planet Mercury has been known for a long time, for thousands of years, people had no idea what it looked like (until NASA transmitted the first pictures in 1974).
Moreover, the ancient astronomers did not immediately realize that they saw the same star in the morning and in the evening. The ancient Romans considered Mercury the patron saint of commerce, travelers and thieves, as well as the messenger of the gods. It is not surprising that a small planet, rapidly moving across the sky after the Sun, received his name.
Mercury is the smallest planet after Pluto (which was stripped of its planetary status in 2006). The diameter is no more than 4880 km and is quite a bit larger than the Moon. Such a modest size and constant proximity to the Sun create difficulties for studying and observing this planet from Earth.
Mercury also stands out for its orbit. It is not circular, but a more elongated elliptical when compared with other planets of the solar system. The minimum distance to the Sun is about 46 million kilometers, the maximum is about 50% more (70 million).
Mercury receives 9 times more sunlight than the surface of the Earth. The lack of an atmosphere to protect from the burning rays of the sun is causing the surface temperature to rise to 430 o C. It is one of the hottest places in the solar system.
The surface of the planet Mercury is the personification of antiquity, timeless. The atmosphere here is very rarefied, and there was never any water at all, so erosion processes were practically absent, except for the consequences of the fall of rare meteorites or collisions with comets.
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Although Mars and Venus are the closest orbits to Earth, Mercury is more likely than others to be the planet closest to Earth, since others are more distant, not so "tied" to the Sun.
There are no seasons on Mercury like on Earth. This is due to the fact that the planet's axis of rotation is at an almost right angle to the orbital plane. As a result, there are areas near the poles that the sun's rays never reach. This suggests that there are glaciers in this cold and dark zone.
Mercury moves faster than any other planet. The combination of its movements leads to the fact that the sunrise on Mercury does not last long, after which the Sun sets and rises again. At sunset, this sequence is repeated in reverse order.
For its size, Mercury is very heavy - apparently, it has a huge iron core. Astronomers believe that the planet was once larger and had thicker outer layers, but billions of years ago it collided with a protoplanet, and part of the mantle and crust flew into space.
Here on Earth, we tend to take time for granted, never realizing that the step with which we measure it is fairly relative.
For example, how we measure our days and years is the actual result of our planet's distance from the sun, the time it takes to orbit around it, and around its own axis. The same is true for other planets in our solar system. While we Earthlings calculate a day 24 hours from dawn to dusk, the length of one day on another planet is significantly different. In some cases, it is very short, while in others, it can last over a year.
A day on Mercury:
Mercury is the closest planet to our Sun, ranging from 46,001,200 km at perihelion (closest distance to the Sun) to 69,816,900 km at aphelion (farthest). The revolution of Mercury on its axis takes 58.646 Earth days, which means that a day on Mercury takes about 58 Earth days from dawn to dusk.
However, it takes only 87,969 Earth days for Mercury to orbit the Sun once (in other words, the orbital period). This means that a year on Mercury is equivalent to approximately 88 Earth days, which in turn means that one year on Mercury lasts 1.5 Mercury days. Moreover, the north polar regions of Mercury are constantly in shadow.
This is due to its axis tilt of 0.034 ° (for comparison, the Earth has 23.4 °), which means that there are no extreme seasonal changes on Mercury, when days and nights can last for months, depending on the season. It is always dark at the poles of Mercury.
A day on Venus:
Also known as the "Earth's twin," Venus is the second closest planet to our Sun, ranging from 107,477,000 km at perihelion to 108,939,000 km at aphelion. Unfortunately Venus is also the slowest planet, this fact is obvious when you look at its poles. Whereas planets in the solar system experienced flattening at the poles due to their rotational speed, Venus did not experience it.
Venus rotates at just 6.5 km / h (compared to Earth's rational speed of 1,670 km / h), which results in a sidereal rotation period of 243.025 days. Technically, this is minus 243.025 days, since Venus's rotation is retrograde (i.e. rotation in the opposite direction of its orbital path around the Sun).
Nevertheless, Venus still revolves around its axis in 243 Earth days, that is, many days pass between its sunrise and sunset. This may sound strange until you know that one Venusian year is 224.071 Earth days. Yes, Venus takes 224 days to complete its orbital period, but more than 243 days to travel from dawn to dusk.
Thus, one day of Venus is slightly larger than the Venus year! It's good that Venus has other similarities to Earth, but this is clearly not a diurnal cycle!
Day on Earth:
When we think of a day on Earth, we tend to think it's just 24 hours. In truth, the sidereal period of the Earth's rotation is 23 hours 56 minutes and 4.1 seconds. So one day on Earth is equivalent to 0.997 Earth days. Oddly, again, people prefer simplicity when it comes to time management, so we're rounding up.
At the same time, there are differences in the length of one day on the planet depending on the season. Due to the tilt of the earth's axis, the amount of sunlight received in some hemispheres will vary. The most striking cases occur at the poles, where day and night can last for several days or even months, depending on the season.
At the North and South Poles during winter, one night can last up to six months, known as the "polar night". In summer, the so-called "polar day" will begin at the poles, where the sun does not set for 24 hours. It's actually not as easy as I would like to imagine.
A day on Mars:
In many ways, Mars can also be called "Earth's twin". Add seasonal fluctuations and water (albeit frozen) to the polar ice cap, and a day on Mars is pretty close to Earth. Mars makes one revolution around its axis in 24 hours 
37 minutes and 22 seconds. This means that one day on Mars is equivalent to 1.025957 Earth days.
The seasonal cycles on Mars are similar to ours on Earth, more than on any other planet, due to its axis tilt of 25.19 °. As a result, Martian days experience similar changes with the Sun rising early and setting late in summer and vice versa in winter.
However, seasonal changes last twice as long on Mars because the Red Planet is at a greater distance from the Sun. This leads to the fact that the Martian year lasts twice as long as the Earth - 686.971 Earth days or 668.5991 Martian days or Sol.
A day on Jupiter:
Given the fact that it is the largest planet in the solar system, one would expect a day on Jupiter to be long. But, as it turns out, the official day on Jupiter lasts only 9 hours 55 minutes and 30 seconds, which is less than a third of the duration of the earth's day. This is due to the fact that the gas giant has a very high rotational speed of about 45300 km / h. This high rotation rate is also one of the reasons the planet has such violent storms.
Pay attention to the use of the word officially. Since Jupiter is not rigid, its upper atmosphere moves at a speed different from that at its equator. Basically, the rotation of Jupiter's polar atmosphere is 5 minutes faster than that of the equatorial atmosphere. Because of this, astronomers use three frames of reference.
System I is used in latitudes from 10 ° N to 10 ° S, where its rotation period is 9 hours 50 minutes and 30 seconds. System II is applied at all latitudes north and south of them, where the rotation period is 9 hours 55 minutes and 40.6 seconds. System III corresponds to the rotation of the planet's magnetosphere, and this period is used by the IAU and IAG to determine the official rotation of Jupiter (i.e. 9 hours 44 minutes and 30 seconds)
So if you could theoretically stand on the clouds of a gas giant, you would see the Sun rise less than once every 10 hours at any latitude of Jupiter. And in one year on Jupiter, the Sun rises about 10,476 times.
A day on Saturn:
The situation of Saturn is very similar to Jupiter. Despite its large size, the planet has an estimated rotational speed of 35,500 km / h. One sidereal rotation of Saturn takes approximately 10 hours 33 minutes, making one day on Saturn less than half an Earth day.
The orbital period of Saturn's rotation is equivalent to 10,759.22 Earth days (or 29.45 Earth years), and a year is approximately 24,491 Saturian days. However, like Jupiter, Saturn's atmosphere rotates at different speeds depending on latitude, requiring astronomers to use three different frames of reference.
System I covers the equatorial zones of the South Equatorial Pole and the North Equatorial Belt, and has a period of 10 hours 14 minutes. System II covers all other latitudes of Saturn, with the exception of the north and south poles, with a rotation period of 10 hours 38 minutes and 25.4 seconds. System III uses radio waves to measure Saturn's internal rotation speed, which resulted in a rotation period of 10 hours 39 minutes 22.4 seconds.
Using these various systemsScientists have obtained various data from Saturn over the years. For example, data from Voyager 1 and 2 during the 1980s indicated that a day on Saturn is 10 hours 45 minutes and 45 seconds (± 36 seconds).
This was revised in 2007 by researchers at UCLA's Department of Earth, Planetary and Space Sciences, resulting in a current estimate of 10 hours and 33 minutes. In many ways, as with Jupiter, the problem of accurate measurements is due to the fact that different parts rotate at different speeds.
A day in Uranus:
As we approached Uranus, the question of how long a day lasts became more difficult. On the one hand, the planet has a stellar rotation period of 17 hours 14 minutes and 24 seconds, which is equivalent to 0.71833 Earth days. Thus, it can be said that a day on Uranus lasts almost as long as a day on Earth. This would be true were it not for the extreme tilt of the axis of this gas-ice giant.
With an axis tilt of 97.77 °, Uranus essentially orbits the Sun on its side. This means that its north or south is facing directly towards the Sun at different time orbital period. When summer is at one pole, the sun will shine there continuously for 42 years. When the same pole is turned away from the Sun (that is, it is winter on Uranus), there will be darkness for 42 years.
Therefore, we can say that one day on Uranus from sunrise to sunset lasts 84 years! In other words, one day on Uranus lasts the same as one year.
In addition, as with other gas / ice giants, Uranus rotates faster at certain latitudes. Consequently, while the planet's rotation at the equator, at approximately 60 ° S latitude, is 17 hours and 14.5 minutes, the visible features of the atmosphere move much faster, making a complete revolution in just 14 hours.
A day on Neptune:
Finally, we have Neptune. Here, too, the measurement of one day is somewhat more complicated. For example, Neptune's sidereal rotation period is approximately 16 hours 6 minutes and 36 seconds (equivalent to 0.6713 Earth days). But due to its gas / ice origin, the poles of the planet rotate faster than the equator.
Whereas the rotation speed magnetic field planets 16.1 hours, the equatorial zone rotates for about 18 hours. Meanwhile, the polar regions rotate for 12 hours. This differential rotation is brighter than any other planet in the solar system, resulting in a strong latitudinal wind shear.
In addition, the planet's axis tilt of 28.32 ° results in seasonal fluctuations similar to those on Earth and Mars. Neptune's long orbital period means that the season lasts for 40 Earth years. But since its axial tilt is comparable to that of Earth, the change in the length of its day over its long year is not so extreme.
As you can see from this summary of the various planets in our solar system, the length of a day depends entirely on our frame of reference. In addition, the seasonal cycle varies depending on the planet in question and where measurements are taken from on the planet.
As soon as the automatic station "Mariner-10" sent from Earth finally reached the almost unexplored planet Mercury and began photographing it, it became clear that there are big surprises awaiting earthlings, one of which is an extraordinary striking resemblance of the surface of Mercury to the Moon. The results of further research plunged the researchers into even greater amazement - it turned out that Mercury has much more in common with the Earth than with its eternal satellite.
Illusory kinship
From the first images transmitted by Mariner-10, the scientists were really looking at the Moon so familiar to them, or at least its twin - on the surface of Mercury there were many craters that at first glance looked completely identical to the moon. And only a careful study of the images made it possible to establish that the hilly areas around the lunar craters, composed of material ejected during the crater-forming explosion, are one and a half times wider than the Mercurian ones - with the same size of the craters. This is explained by the fact that the large force of gravity on Mercury prevented the more distant dispersal of the soil. It turned out that on Mercury, like on the Moon, there are two main types of terrain - analogs of lunar continents and seas.
The mainland regions are the most ancient geological formations of Mercury, consisting of areas dotted with craters, inter-crater plains, mountainous and hilly formations, as well as ruled areas covered with numerous narrow ridges.
Analogs of the lunar seas are the smooth plains of Mercury, which are younger in age than the continents, and somewhat darker than the continental formations, but still not as dark as the lunar seas. Such areas on Mercury are concentrated in the region of the Zhara Plain, a unique and largest ring structure on the planet with a diameter of 1,300 km. The plain got its name not by chance - a meridian of 180 ° W passes through it. etc., it is he (or the opposite meridian 0 °) that is located in the center of the hemisphere of Mercury, which is facing the Sun when the planet is at the minimum distance from the Luminary. At this time, the planet's surface heats up most of all in the regions of these meridians, and in particular in the region of the Zhara plain. It is surrounded by a mountainous ring that delimits a huge circular depression formed by early stage geological history of Mercury. Subsequently, this depression, as well as the areas adjacent to it, were flooded with lavas, which solidified and smooth plains arose.
On the other side of the planet, exactly opposite the depression in which the Zhara Plain is located, there is another unique formation - a hilly-ruled area. It consists of numerous large hills (5-10 km in diameter and up to 1-2 km in height) and is crossed by several large rectilinear valleys, clearly formed along the fault lines of the planet's crust. The location of this area in the area opposite to the Zhara Plain served as the basis for the hypothesis that the hilly-ruled relief was formed due to the focusing of seismic energy from the impact of an asteroid that formed the Zhara Basin. This hypothesis was indirectly confirmed when areas with a similar topography were soon discovered on the Moon, located diametrically opposite the Sea of \u200b\u200bRains and the East Sea - the two largest ring formations of the Moon.
The structural pattern of the Mercury crust is determined to a large extent, as in the Moon, by large impact craters, around which systems of radial-concentric faults are developed, which dismember the Mercury crust into blocks. The largest craters have not one, but two annular concentric bars, which also resembles a lunar structure. On the captured half of the planet, 36 such craters have been identified.
Despite the general similarity of the Mercurian and lunar landscapes, completely unique geological structures were discovered on Mercury, which had not been observed before on any of the planetary bodies. They were called lobe-shaped ledges, since their outlines on the map are typical of rounded protrusions - “lobes” up to several tens of kilometers across. The height of the ledges is from 0.5 to 3 km, while the largest of them reach 500 km in length. These ledges are rather steep, but in contrast to the lunar tectonic ledges, which have a pronounced downward bend of the slope, the Mercurian lobe-like ones have a smoothed line of surface bend in their upper part.
These ledges are located in the ancient continental regions of the planet. All their features give reason to consider them as a surface expression of the compression of the upper layers of the planet's crust.
Calculations of the magnitude of the compression, made according to the measured parameters of all the scarps on the captured half of Mercury, indicate a reduction in the area of \u200b\u200bthe crust by 100 thousand km 2, which corresponds to a decrease in the radius of the planet by 1–2 km. Such a decrease could be caused by the cooling and solidification of the planet's interior, in particular its core, which continued even after the surface had already become solid.
Calculations have shown that the iron core should have a mass of 0.6-0.7 times the mass of Mercury (for the Earth, the same value is 0.36). If all iron is concentrated in the Mercury core, then its radius will be 3/4 of the planet's radius. Thus, if the radius of the core is approximately 1,800 km, then it turns out that inside Mercury there is a giant iron ball the size of the Moon. The two outer stone shells - the mantle and the crust - account for only about 800 km. Such internal structure very similar to the structure of the Earth, although the dimensions of the shells of Mercury are determined only in the most general terms: even the thickness of the crust is unknown, it is assumed that it can be 50-100 km, then a layer about 700 km thick remains on the mantle. On Earth, the mantle occupies the predominant part of the radius.
Relief details. The giant Discovery scarp, 350 km long, crosses two craters 35 and 55 km in diameter. The maximum step height is 3 km. It was formed when the upper layers of Mercury's crust moved from left to right. This was due to the warping of the planet's crust during the compression of the metal core, caused by its cooling. The ledge received the name of the ship of James Cook.
Photo map of the largest ring structure on Mercury - the Zhara Plain, surrounded by the Zhara Mountains. The diameter of this structure is 1300 km. Only its eastern part is visible, and the central and western parts, not illuminated in this image, have not yet been studied. Area of \u200b\u200bthe meridian 180 ° W - this is the region of Mercury most strongly heated by the Sun, which is reflected in the names of the plain and mountains. The two main terrain types on Mercury - ancient highly cratered regions (dark yellow on the map) and younger smooth plains (brown on the map) - reflect the two main periods of the planet's geological history - the period of massive fall of large meteorites and the subsequent period of outpouring of highly mobile ones. presumably basaltic lavas.
Giant craters with a diameter of 130 and 200 km with an additional shaft at the bottom, concentric with the main annular shaft.
The winding ledge of Santa Maria, named for the ship of Christopher Columbus, traverses ancient craters and the later plains.
The hilly-ruled area is a unique in its structure area of \u200b\u200bthe surface of Mercury. There are almost no small craters here, but many clusters of low hills, crossed by rectilinear tectonic faults.
Names on the map. The names of the details of the relief of Mercury, revealed in the images of "Mariner 10", were given by the International Astronomical Union. The craters are named after world cultural figures - famous writers, poets, painters, sculptors, composers. To designate the plains (except the Zhary plain), the names of the planet Mercury were used on different languages... Extended linear depressions - tectonic valleys - were named after radio observatories that contributed to the study of the planets, and two ridges - large linear elevations, were named after astronomers Schiaparelli and Antoniadi, who made many visual observations. The largest blade-like ledges were named after sea ships on which the most significant voyages in the history of mankind were made.
Iron heart
Other data obtained by "Mariner-10" and showed that Mercury has an extremely weak magnetic field, the magnitude of which is only about 1% of the earth's, was also a surprise. This seemingly insignificant circumstance was extremely important for scientists, since of all the planetary bodies of the terrestrial group, only the Earth and Mercury have a global magnetosphere. And the only most plausible explanation for the nature of the Mercurian magnetic field may be the presence in the planet's interior of a partially molten metal core, again similar to that of the Earth. Apparently, this core of Mercury is very large, as indicated by the high density of the planet (5.4 g / cm 3), which suggests that Mercury contains a lot of iron, the only fairly widespread heavy element in nature.
To date, several possible explanations have been put forward for the high density of Mercury with its relatively small diameter. According to the modern theory of planetary formation, it is believed that in the preplanetary dust cloud the temperature of the region adjacent to the Sun was higher than in its marginal parts, therefore, light (so-called volatile) chemical elements were carried out to remote, colder parts of the cloud. As a result, in the near-solar region (where Mercury is now located), a predominance of heavier elements was created, the most common of which is iron.
Other explanations associate the high density of Mercury with the chemical reduction of oxides (oxides) of light elements to their heavier, metallic form under the influence of very strong solar radiation, or with the gradual evaporation and volatilization of the outer layer of the planet's original crust into space under the influence of solar heating, or with the fact that a significant part of the "stone" shell of Mercury was lost as a result of explosions and emissions of matter into outer space during collisions with celestial bodies of smaller sizes, for example, asteroids.
In terms of average density, Mercury stands apart from all other terrestrial planets, including the Moon. Its average density (5.4 g / cm 3) is second only to the density of the Earth (5.5 g / cm 3), and if we keep in mind that the Earth's density is affected by a stronger compression of matter due to the larger size of our planet, then it turns out that with equal sizes of planets, the density of the mercury matter would be the greatest, exceeding the earth's by 30%.
Hot Ice
Based on the available data, the surface of Mercury, receiving a huge amount of solar energy, is a real hell. Judge for yourself - the average temperature at the time of the Mercurian noon is about + 350 ° C. Moreover, when Mercury is at the minimum distance from the Sun, it rises to + 430 ° С, while at the maximum distance it drops to only + 280 ° С. However, it has also been established that immediately after sunset the temperature in the equatorial region drops sharply to -100 ° C, and by midnight it generally reaches -170 ° C, but after dawn the surface quickly warms up to + 230 ° C. Measurements carried out from the Earth in the radio range showed that inside the soil at a shallow depth the temperature does not depend on the time of day at all. That says about the high heat-insulating properties of the surface layer, but since daylight hours on Mercury lasts 88 Earth days, then during this time it is good to warm up, albeit to a shallow depth, all parts of the surface have time.
It would seem that talking about the possibility of ice existence on Mercury in such conditions is at least absurd. But in 1992, during radar observations from the Earth near the north and south poles of the planet, areas were first discovered that very strongly reflect radio waves. It was these data that were interpreted as evidence of the presence of ice in the near-surface Mercurian layer. Radar made from the Arecibo radio observatory on the island of Puerto Rico, as well as from the NASA Deep Space Communications Center in Goldstone (California), revealed about 20 rounded spots with a diameter of several tens of kilometers with increased radio reflection. Presumably, these are craters, into which, due to their close location to the poles of the planet, the sun's rays fall only in passing or do not fall at all. Such craters, called permanently shaded, are also found on the Moon, in which measurements from satellites revealed the presence of a certain amount of water ice. Calculations have shown that in the depressions of constantly shaded craters near the poles of Mercury it can be cold enough (–175 ° С) for ice to exist there for a long time. Even in flat areas near the poles, the calculated daily temperature does not exceed –105 ° С. There are still no direct measurements of the surface temperature of the polar regions of the planet.
Despite observations and calculations, the existence of ice on the surface of Mercury or at a shallow depth beneath it has not yet received unambiguous proof, since rocky rocks containing compounds of metals with sulfur and possible metal condensates on the planet's surface, such as ions, have an increased radio reflection sodium deposited on it as a result of the constant "bombardment" of Mercury with particles of the solar wind.
But then the question arises: why is the distribution of areas that strongly reflect radio signals, precisely confined to the polar regions of Mercury? Maybe the rest of the territory is protected from the solar wind by the planet's magnetic field? Hopes for clarification of the riddle about ice in the kingdom of heat are associated only with the flight to Mercury of new automatic space stations equipped with measuring instruments that make it possible to determine chemical composition surface of the planet. Two such stations - Messenger and Bepi-Colombo - are already preparing to fly.
Schiaparelli's fallacy. Astronomers call Mercury a difficult object to observe, since in our sky it moves away from the Sun by no more than 28 ° and it has to be observed always low above the horizon, through atmospheric haze against the background of morning dawn (in autumn) or in the evenings immediately after sunset (in spring ). In the 1880s, the Italian astronomer Giovanni Schiaparelli, based on his observations of Mercury, concluded that this planet makes one revolution around its axis in exactly the same time as one revolution in its orbit around the Sun, that is, "days" on it are equal " year ". Consequently, the same hemisphere is always facing the Sun, the surface of which is constantly hot, but on the opposite side of the planet eternal darkness and cold reign. And since the authority of Schiaparelli as a scientist was great, and the conditions for observing Mercury were difficult, for almost a hundred years this position was not questioned. And only in 1965 by radar observations using the largest radio telescope Arecibo, American scientists G. Pettengill and R. Dyce for the first time reliably determined that Mercury makes one revolution around its axis in about 59 Earth days. This was the largest discovery in planetary astronomy of our time, which literally shook the foundations of the concept of Mercury. And this was followed by another discovery - Professor of the University of Padua D. Colombo noticed that the time of Mercury's revolution around the axis corresponds to 2/3 of the time of its revolution around the Sun. This was interpreted as the presence of a resonance between the two rotations, which arose due to the gravitational influence of the Sun on Mercury. In 1974, the American automatic station "Mariner-10", for the first time flying around the planet, confirmed that a day on Mercury lasts more than a year. Today, despite the development of space and radar studies of planets, observations of Mercury traditional methods optical astronomy continued, albeit with the use of new instruments and computerized data processing methods. Recently, at the Abastumani Astrophysical Observatory (Georgia), together with the Space Research Institute of the Russian Academy of Sciences, a study of the photometric characteristics of the surface of Mercury was carried out, which provided new information about the microstructure of the upper soil layer.
In the vicinity of the sun. The closest planet to the Sun, Mercury, moves in a highly elongated orbit, then approaching the Sun at a distance of 46 million km, then moving away from it by 70 million km. The strongly elongated orbit differs sharply from the almost circular orbits of the rest of the terrestrial planets - Venus, Earth and Mars. The axis of rotation of Mercury is perpendicular to the plane of its orbit. One revolution in orbit around the Sun (Mercurian year) lasts 88, and one revolution around the axis - 58.65 Earth days. The planet rotates around its axis in the forward direction, that is, in the same direction in which it moves along its orbit. As a result of the addition of these two motions, the duration of a solar day on Mercury is 176 Earth's. Among the nine planets of the solar system, Mercury, whose diameter is 4,880 km, is in the penultimate place in size, only Pluto is smaller than it. The force of gravity on Mercury is 0.4 of the earth's, and the surface area (75 million km 2) is twice the lunar.
Coming Messengers
The start of the second in the history of the automatic station directed to Mercury - "Messenger" - NASA plans to carry out in 2004. After the launch, the station should fly twice (in 2004 and 2006) near Venus, the gravitational field of which will bend its trajectory so that the station will accurately reach Mercury. The studies are planned to be carried out in two phases: first, introductory - from the flyby trajectory at two encounters with the planet (in 2007 and 2008), and then (in 2009-2010) detailed - from the orbit of an artificial satellite of Mercury, on which work will take place during one earth year.
When flying near Mercury in 2007, the eastern half of the unexplored hemisphere of the planet should be captured, and a year later - the western one. Thus, for the first time, a global photographic map of this planet will be obtained, and this alone would be enough to consider this flight quite successful, but the Messenger's program of work is much more extensive. During the two planned flights, the planet's gravitational field will "slow down" the station so that at the next, third meeting, it could go into the orbit of an artificial satellite of Mercury with a minimum distance of 200 km from the planet and a maximum distance of 15 200 km. The orbit will be located at an angle of 80 ° to the planet's equator. The low section will be located above its northern hemisphere, which will allow a detailed study of both the planet's largest Plain Zhara, and the alleged "cold traps" in craters near the North Pole, which do not get the light of the Sun and where ice is expected.
During the work of the station in orbit around the planet, it is planned to perform a detailed survey of its entire surface in various ranges of the spectrum in the first 6 months, including color images of the terrain, determination of the chemical and mineralogical compositions of surface rocks, measurement of the content of volatile elements in the near-surface layer to search for places of ice concentration.
In the next 6 months, very detailed studies of individual terrain objects will be carried out, the most important for understanding the history of the geological development of the planet. Such objects will be selected based on the results of the global survey carried out at the first stage. Also, a laser altimeter will measure the heights of surface details to obtain survey topographic maps. A magnetometer, located far from the station on a pole 3.6 m long (to avoid interference from instruments), will determine the characteristics of the planet's magnetic field and possible magnetic anomalies on Mercury itself.
A joint project of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) - BepiColombo - is called upon to take over the baton from Messenger and begin in 2012 the study of Mercury using three stations at once. Here, prospecting work is planned to be carried out using two artificial satellites at the same time, as well as a landing apparatus. In the planned flight, the planes of the orbits of both satellites will pass through the poles of the planet, which will allow observations to cover the entire surface of Mercury.
The main satellite in the form of a low prism with a mass of 360 kg will move in a weakly extended orbit, then approaching the planet up to 400 km, then moving away from it by 1,500 km. This satellite will host a whole range of instruments: 2 television cameras for overview and detailed surface surveys, 4 spectrometers for studying the chi-ranges (infrared, ultraviolet, gamma, X-ray), as well as a neutron spectrometer designed to detect water and ice. In addition, the main satellite will be equipped with a laser altimeter, which should be used for the first time to map the heights of the entire planet's surface, as well as a telescope to search for asteroids potentially dangerous for collisions with the Earth, which enter the inner regions of the solar system, crossing the earth's orbit.
Overheating by the Sun, from which 11 times more heat comes to Mercury than to the Earth, can lead to failure of electronics operating at room temperature, one half of the Messenger station will be covered with a semi-cylindrical heat-insulating screen made of special ceramic fabric by Nextel.
An auxiliary satellite in the form of a flat cylinder with a mass of 165 kg, called magnetospheric, is planned to be launched into a highly elongated orbit with a minimum distance of 400 km from Mercury and a maximum distance of 12,000 km. Working in tandem with the main satellite, it will measure the parameters of remote regions of the planet's magnetic field, while the main one will be engaged in observing the magnetosphere near Mercury. Such joint measurements will make it possible to construct a volumetric picture of the magnetosphere and its changes in time when interacting with streams of charged particles of the solar wind that change their intensity. On the auxiliary satellite, a television camera will also be installed to take pictures of the surface of Mercury. The magnetospheric satellite is being created in Japan, and the main one is being developed by scientists from European countries.
The Scientific Research Center named after G.N. Babakin at the S.A. Lavochkin, as well as companies from Germany and France. The BepiColombo is planned to be launched in 2009-2010. In this regard, two options are being considered: either a single launch of all three vehicles by the Ariane-5 rocket from the Kuru cosmodrome during French Guiana (South America), or - two separate launches from the Baikonur cosmodrome in Kazakhstan by Russian Soyuz-Fregat missiles (on one - the main satellite, on the other - a landing apparatus and magnetospheric satellite). It is assumed that the flight to Mercury will last 2-3 years, during which the spacecraft should fly relatively close to the Moon and Venus, the gravitational effect of which will "correct" its trajectory, giving the direction and speed necessary to reach the nearest vicinity of Mercury in 2012.
As already mentioned, research from satellites is planned to be carried out within one earth year. As for the landing block, it will be able to work for a very short time - the strong heating that it must undergo on the surface of the planet will inevitably lead to the failure of its electronic devices. During the interplanetary flight, a small disk-shaped lander (diameter 90 cm, weight 44 kg) will be "on the back" of the magnetospheric satellite. After their separation near Mercury, the lander will be launched into orbit of an artificial satellite with an altitude of 10 km above the planet's surface.
Another maneuver will put him on a descent trajectory. When 120 m remains to the surface of Mercury, the lander's speed should decrease to zero. At this moment, it will begin a free fall onto the planet, during which plastic bags will be filled with compressed air - they will cover the device from all sides and soften its impact on the surface of Mercury, which it touches at a speed of 30 m / s (108 km / h).
To reduce the negative impact of solar heat and radiation, it is planned to land on Mercury in the polar region on the night side, not far from the dividing line between the dark and illuminated parts of the planet, so that after about 7 Earth days, the device "sees" the dawn and rises above the horizon The sun. In order for the onboard television camera to be able to obtain images of the terrain, it is planned to equip the landing block with a kind of searchlight. Using two spectrometers, it will be determined which chemical elements and minerals are contained in the landing point. A small probe, nicknamed the "mole", will penetrate deep into the depths to measure the mechanical and thermal characteristics of the soil. A seismometer will try to register possible “mercurrequakes”, which, by the way, are very likely.
It is also planned that a miniature rover will descend from the lander to the surface to study the properties of the soil in the adjacent territory. Despite the grandiose plans, detailed study of Mercury is just beginning. And the fact that earthlings intend to spend a lot of effort and money on this is by no means accidental. Mercury is the only celestial body, the internal structure of which is so similar to that of the earth, therefore, it is of exceptional interest for comparative planetology. Perhaps the exploration of this distant planet will shed light on the mysteries hidden in the biography of our Earth.
The BepiColombo mission over the surface of Mercury: in the foreground - the main orbiting satellite, in the distance - the magnetospheric module.
Lonely guest.Mariner 10 is the only spacecraft to have explored Mercury. The information he received 30 years ago is still the best source of information about this planet. The flight of "Mariner-10" is considered extremely successful - instead of the planned one once, he conducted studies of the planet three times. All modern maps of Mercury and the vast majority of data on its physical characteristics are based on the information he received during the flight. Having reported all possible information about Mercury, "Mariner-10" has exhausted the resource of "vital activity", but it still continues to silently move along the same trajectory, meeting with Mercury every 176 Earth days - exactly after two revolutions of the planet around the Sun and after three revolutions of it around its axis. Because of this synchronization of motion, it always flies over the same region of the planet illuminated by the Sun, at exactly the same angle as during its very first flight.
Solar dances. The most impressive sight in the Mercury firmament is the Sun. There it looks 2-3 times larger than in the earthly sky. The peculiarities of the combination of the rotation speeds of the planet around its axis and around the Sun, as well as the strong elongation of its orbit, lead to the fact that the apparent movement of the Sun across the black Mercury sky is not at all the same as on Earth. In this case, the path of the Sun looks different at different longitudes of the planet. So, in the regions of the meridians 0 and 180 ° W. early in the morning in the eastern part of the sky above the horizon, an imaginary observer could see a "small" (but 2 times larger than in the Earth's sky), very quickly rising above the horizon Luminary, the speed of which gradually slows down as it approaches the zenith, and it becomes brighter and hotter, increasing in size by 1.5 times - this is Mercury in its highly elongated orbit closer to the Sun. Having barely passed the zenith point, the Sun freezes, moves back a little for 2-3 Earth days, freezes again, and then begins to go down with an ever-increasing speed and noticeably decrease in size - this is Mercury moving away from the Sun, going into an elongated part of its orbit - and with great speed disappears behind the horizon in the west.
The diurnal run of the Sun near 90 and 270 ° W looks quite different. Here the Luminary writes quite amazing pirouettes - there are three sunrises and three sunsets per day. In the morning, a bright luminous disk of enormous size appears very slowly from the horizon in the east (3 times larger than on the earth's firmament), it rises slightly above the horizon, stops, and then goes down and disappears for a short time behind the horizon.
Soon a re-rise follows, after which the Sun begins to slowly creep up through the sky, gradually accelerating its course and at the same time rapidly decreasing in size and dimming. At the zenith point, this "small" Sun flies by at high speed, and then slows down, grows in size and slowly disappears behind the evening horizon. Soon after the first sunset, the Sun rises again to a small height, briefly freezes in place, and then drops back to the horizon and sets completely.
Such "zigzags" of the solar motion occur because on a short segment of the orbit during the passage of perihelion (the minimum distance from the Sun), the angular velocity of Mercury's orbit around the Sun becomes greater than the angular velocity of its rotation around the axis, which leads to the movement of the Sun in the planet's sky for a short period of time (about two Earth days) reverse its usual course. But the stars in the sky of Mercury move three times faster than the Sun. A star that appeared simultaneously with the Sun above the morning horizon will set in the west before noon, that is, before the Sun reaches its zenith, and will have time to rise again in the east before the Sun has set.
The sky over Mercury is black both day and night, and all because there is practically no atmosphere. Mercury is surrounded only by the so-called exosphere - a space so rarefied that its constituent neutral atoms never collide. In it, according to observations through a telescope from Earth, as well as in the process of flights around the planet of the Mariner-10 station, atoms of helium (they prevail), hydrogen, oxygen, neon, sodium and potassium were found. The atoms that make up the exosphere are "knocked out" from the surface of Mercury by photons and ions, particles arriving from the Sun, and also by micrometeorites. The absence of an atmosphere leads to the fact that there are no sounds on Mercury, since there is no elastic medium - air that transmits sound waves.
Georgy Burba, Candidate of Geographical Sciences
Time on Earth is taken for granted. People don't think that the interval by which time is measured is relative. For example, days and years are measured according to physical factors: The distance from the planet to the Sun is taken into account. One year is equal to the time it takes for the planet to go around the Sun, and one day is the time it takes to fully rotate around its axis. The same principle is used to calculate the time on other celestial bodies of the solar system. Many people are interested in how long a day lasts on Mars, Venus and other planets?
On our planet, a day lasts 24 hours. It takes just so many hours for the Earth to rotate around its axis. The length of the day on Mars and other planets is different: somewhere it is short, but somewhere it is very long.
Timing
To find out how long a day lasts on Mars, you can use solar or sidereal days. The last variant of measurements represents the period during which the planet makes one rotation around its axis. The day measures the time that is necessary for the stars to become in the sky in the same position from which the countdown began. Earth's stellar path is 23 hours and almost 57 minutes.
A solar day is a unit of time it takes a planet to orbit around an axis relative to sunlight. The principle of measuring by this system is the same as when measuring the day of a sidereal day, only the Sun is used as a reference point. Sidereal and solar days can be different.
And how long is a day on Mars in the star and solar system? A sidereal day on the red planet is 24 and a half hours. Sunny days last a little longer - 24 hours and 40 minutes. A day on Mars is 2.7% longer than on Earth.
When sending spacecraft to explore Mars, the time on it is taken into account. The devices have a special built-in clock that differs from the earthly clock by 2.7%. Knowing how long a day lasts on Mars allows scientists to create special rovers that are synchronized with the Martian days. The use of special clocks is important for science, since the rovers are solar-powered. As an experiment for Mars, a clock was developed that takes into account the solar day, but they failed to apply.
The zero meridian on Mars is the one that passes through the crater called Airy. However, there are no time zones on the red planet like there are on Earth.
Martian time
Knowing how many hours in a day are on Mars, you can calculate how long a year is. The seasonal cycle is similar to that of the Earth: Mars has the same inclination as the Earth (25.19 °) in relation to its own orbital plane. From the sun to the red planet, the distance varies at different periods from 206 to 249 million kilometers.
Temperature readings differ from ours:
- average temperature -46 ° С;
- during the period of distance from the Sun, the temperature is about -143 ° С;
- in summer - -35 ° С.
Water on Mars
An interesting discovery was made by scientists in 2008. The rover found water ice at the planet's poles. Prior to this discovery, it was believed that there was only carbon dioxide on the surface. Even later it turned out that precipitation falls on the red planet in the form of snow, and carbon dioxide falls near the south pole.
Throughout the year, Mars has storms that extend over hundreds of thousands of kilometers. They interfere with tracking what is happening on the surface.
A year on Mars
Around the Sun, the red planet makes a circle in 686 Earth days, moving at a speed of 24 thousand kilometers per second. A whole system of notation for Martian years has been developed.
When studying the question of how long a day on Mars lasts in hours, mankind has made many sensational discoveries. They show that the red planet is close to Earth.
Length of a year on Mercury
Mercury is a planet close to the Sun. It makes a revolution around its axis in 58 earth days, that is, one day on Mercury is 58 earth days. And to fly around the Sun, the planet needs only 88 Earth days. This amazing discovery shows that on this planet a year lasts almost three Earth months, and while our planet orbits one circle around the Sun, Mercury makes more than four revolutions. And how long is a day on Mars and other planets when compared with Mercury time? It's amazing, but in just one and a half Martian days, a whole year passes on Mercury.
Time on Venus
The time on Venus is unusual. One day on this planet lasts 243 earth days, and a year on this planet lasts 224 earth days. It seems strange, but such is the mysterious Venus.
Time on Jupiter
Jupiter is the largest planet in our solar system. Based on its size, many believe that the day on it lasts a long time, but this is not the case. Its duration is 9 hours 55 minutes, which is less than half the length of our earthly day. The gas giant rotates rapidly on its axis. By the way, because of him, constant hurricanes and strong storms are raging on the planet.
Time on Saturn
A day on Saturn lasts about the same as on Jupiter and is 10 hours 33 minutes. But the year lasts approximately 29,345 Earth years.
Time on Uranus
Uranus is an unusual planet, and it is not so easy to determine how long daylight hours on it will last. A sidereal day on the planet lasts 17 hours and 14 minutes. However, the giant has a strong axial tilt, which is why it rotates around the Sun almost on its side. Because of this, summer at one pole will last 42 Earth years, while at the other pole there will be night at that time. When the planet rotates, the other pole will be illuminated for 42 years. Scientists have come to the conclusion that a day on the planet lasts 84 Earth years: one Uranium year lasts almost one Uranium day.
Time on other planets
Dealing with the question of how long a day and a year last on Mars and other planets, scientists have found unique exoplanets, where a year lasts only 8.5 Earth hours. This planet is called Kepler 78b. Another planet, KOI 1843.03, was also discovered, with a shorter period of rotation around its sun - only 4.25 Earth hours. Every day a person would become three years older if he lived not on Earth, but on one of these planets. If people can adjust to the planetary year, then the best way is to go to Pluto. On this dwarf, the year is 248.59 Earth years.
0.147 Earthly
0.056 Earthy
0.055 Terrestrial
0.984 Earthly
0,38
281.01 °
0.106 (geom.albedo)
24.9% sodium
9.5%, A. oxygen
7.0% argon
5.9% helium
5.6%, M. oxygen
5.2% nitrogen
3.6% carbon dioxide
3.4% water
3.2% hydrogen
Mercury in natural color (image Mariner 10)
Mercury - the closest planet to the Sun in the Solar System, revolves around the Sun in 88 Earth days. Mercury belongs to the inner planets, as its orbit is closer to the Sun than the main asteroid belt. After Pluto was deprived of its planetary status in 2006, Mercury passed the title of the smallest planet in the solar system. The apparent magnitude of Mercury ranges from −2.0 to 5.5, but it is not easy to see due to its very small angular distance from the Sun (maximum 28.3 °). At high latitudes, the planet can never be seen in the dark night sky: Mercury is always hiding in the morning or evening dawn. Optimal time for observations of the planet, there are morning or evening twilight during the periods of its elongations (periods of the maximum distance of Mercury from the Sun in the sky, occurring several times a year).
It is convenient to observe Mercury at low latitudes and near the equator: this is due to the fact that the duration of twilight there is the shortest. It is much more difficult to find Mercury in middle latitudes and only during the period of the best elongations, and in high latitudes it is impossible at all.
So far, relatively little is known about the planet. The Mariner-10 apparatus, which studied Mercury in -1975, managed to map only 40-45% of the surface. In January 2008, the interplanetary station MESSENGER flew past Mercury, which will enter orbit around the planet in 2011.
In terms of its physical characteristics, Mercury resembles the Moon and is highly cratered. The planet has no natural satellites, but it has a very rarefied atmosphere. The planet has a large iron core, which is the source of the magnetic field in its entirety, which is 0.1 of the earth's. The core of Mercury makes up 70 percent of the entire volume of the planet. The temperature on the surface of Mercury ranges from 90 to 700 (−180 to +430 ° C). The solar side warms up much more than the polar regions and the far side of the planet.
Despite its smaller radius, Mercury still surpasses the mass of such satellites of giant planets such as Ganymede and Titan.
The astronomical symbol of Mercury is a stylized image of the winged helmet of the god Mercury with his caduceus.
History and name
The earliest evidence for the observation of Mercury can be found in Sumerian cuneiform texts dating back to the third millennium BC. e. The planet is named after the god of the Roman pantheon Mercury, analogue of Greek Hermes and Babylonian Naboo... The ancient Greeks of the time of Hesiod called Mercury "Στίλβων" (Stilbon, Shiny). Until the 5th century BC e. the Greeks believed that Mercury, visible in the evening and morning sky, are two different objects. In ancient India, Mercury was called Buddha (बुध) and Roginea... In Chinese, Japanese, Vietnamese, and Korean, Mercury is called Water star (水星) (in accordance with the concept of the "Five Elements." In Hebrew, the name of Mercury sounds like "Kohav Hama" (כוכב חמה) ("Solar planet").
Planet movement
Mercury moves around the Sun in a rather highly elongated elliptical orbit (eccentricity 0.205) at an average distance of 57.91 million km (0.387 AU). At perihelion, Mercury is 45.9 million km from the Sun (0.3 AU), at aphelion - 69.7 million km (0.46 AU) At perihelion, Mercury is more than one and a half times closer to the Sun than in aphelion. The inclination of the orbit to the plane of the ecliptic is 7 °. For one revolution in orbit, Mercury spends 87.97 days. The average speed of the planet in orbit is 48 km / s.
For a long time, it was believed that Mercury is constantly facing the Sun by the same side, and one revolution around the axis takes it the same 87.97 days. Observations of details on the surface of Mercury, performed at the limit of resolving power, did not seem to contradict this. This misconception was due to the fact that the most favorable conditions for the observation of Mercury, they are repeated after a triple synodic period, that is, 348 Earth days, which is approximately equal to six times the rotation period of Mercury (352 days), therefore, approximately the same area of \u200b\u200bthe planet's surface was observed at different times. On the other hand, some astronomers believed that Mercury days were roughly the same as Earth's. The truth was revealed only in the mid-1960s, when the radar of Mercury was carried out.
It turned out that the Mercurian sidereal days are equal to 58.65 Earth days, that is, 2/3 of the Mercurian year. Such commensurability of the periods of rotation and revolution of Mercury is a phenomenon unique for the solar system. It is supposedly explained by the fact that the tidal action of the Sun took away angular momentum and slowed down the rotation, which was initially faster, until both periods were connected by an integer ratio. As a result, in one Mercury year, Mercury manages to turn around its axis by one and a half revolutions. That is, if at the time of the passage of perihelion by Mercury a certain point of its surface is directed exactly to the Sun, then at the next passage of the perihelion exactly the opposite point of the surface will be directed to the Sun, and after another Mercury year the Sun will return to the zenith above the first point. As a result, a solar day on Mercury lasts two Mercury years or three Mercury sidereal days.
As a result of such a movement of the planet, it is possible to distinguish "hot longitudes" on it - two opposite meridians, which alternately face the Sun during the passage of Mercury's perihelion, and on which, because of this, it is especially hot even by Mercury standards.
The combination of planetary movements gives rise to another unique phenomenon. The speed of rotation of the planet around the axis is practically constant, while the speed of orbital motion is constantly changing. In the orbital segment near the perihelion, for about 8 days, the orbital velocity exceeds the rotational velocity. As a result, the Sun stops in the Mercury sky and begins to move in the opposite direction - from west to east. This effect is sometimes called the effect of Joshua, after the main character of the Book of Joshua from the Bible, who stopped the movement of the Sun (Joshua, X, 12-13). For an observer at longitudes 90 ° from "hot longitudes", the Sun rises (or sets) twice.
It is also interesting that, although Mars and Venus are the closest in orbits to the Earth, it is Mercury that is most of the time the planet closest to the Earth than any other (since others are more distant, not being so "tied" to the Sun).
physical characteristics
Comparative sizes of Mercury, Venus, Earth and Mars
Mercury is the smallest planet in the terrestrial group. Its radius is only 2439.7 ± 1.0 km, which is less than the radius of Jupiter's moon Ganymede and Saturn's moon Titan. The mass of the planet is 3.3 × 10 23 kg. The average density of Mercury is quite high - 5.43 g / cm³, which is only slightly less than the density of the Earth. Given that the Earth is larger in size, the density value of Mercury indicates increased content in its bowels of metals. The acceleration due to gravity on Mercury is 3.70 m / s². The second space velocity is 4.3 km / s.
Kuiper Crater (just below the center). MESSENGER satellite image
One of the most noticeable features of the surface of Mercury is the Plain of Heat (lat. Caloris planitia). This crater got its name because it is located near one of the "hot longitudes". Its diameter is about 1300 km. Probably, the body, upon impact of which the crater was formed, had a diameter of at least 100 km. The impact was so strong that seismic waves, passing the entire planet and focusing on the opposite point of the surface, led to the formation of a kind of crossed "chaotic" landscape here.
Atmosphere and physical fields
When the spacecraft "Mariner-10" flew past Mercury, it was established that the planet has an extremely rarefied atmosphere, the pressure of which is 5 × 10 11 times less than the pressure of the earth's atmosphere. Under these conditions, atoms are more likely to collide with the planet's surface than with each other. It is composed of atoms captured from the solar wind or knocked out by the solar wind from the surface - helium, sodium, oxygen, potassium, argon, hydrogen. The average lifetime of a certain atom in the atmosphere is about 200 days.
Mercury has a magnetic field, the intensity of which is 300 times less than the intensity of the Earth's magnetic field. Mercury's magnetic field has a dipole structure and is highly symmetric, and its axis deviates by only 2 degrees from the planet's rotation axis, which imposes a significant restriction on the range of theories explaining its origin.
Research
A snapshot of a section of the surface of Mercury, obtained by the MESSENGER apparatus
Mercury is the least studied terrestrial planet. Only two apparatuses were sent to investigate it. The first was Mariner 10, which flew past Mercury three times in -1975; the maximum approach was 320 km. As a result, several thousand images were obtained, covering approximately 45% of the planet's surface. Further studies from Earth have shown the possibility of water ice in polar craters.
Mercury in art
- In Boris Lyapunov's science fiction story "Closest to the Sun" (1956), Soviet cosmonauts for the first time land on Mercury and Venus to study them.
- In Isaac Asimov's story "The Great Sun of Mercury" (a series about Lucky Starr), the action takes place on Mercury.
- Isaac Asimov's short stories Runaround and The Dying Night, written in 1941 and 1956, respectively, describe Mercury facing the Sun on one side. Moreover, in the second story, the solution to the detective plot is built on this fact.
- Francis Karsak's science fiction novel The Flight of the Earth, along with the main plot, describes a scientific station for the study of the sun, located at the North Pole of Mercury. Scientists live on a base located in the eternal shadow of deep craters, and observations are carried out from giant towers constantly illuminated by a star.
- In Alan Nurs' science fiction novel "Through the Sunny Side", the main characters cross the side of Mercury facing the Sun. The story is written in accordance with the scientific views of its time, when it was assumed that Mercury is constantly facing the Sun with one side.
- In the anime animated series "Sailor Moon", the planet is personified by the warrior girl Sailor Mercury, aka Ami Mitsuno. Her attack lies in the power of water and ice.
- In the science fiction story by Clifford Simak "Once on Mercury", the main field of action is Mercury, and the energy form of life on it - balls, surpasses humanity by millions of years of development, having long passed the stage of civilization.
Notes
see also
Literature
- Bronstein V. Mercury is the closest to the Sun // Aksyonova M.D.Encyclopedia for children. T. 8. Astronomy - M .: Avanta +, 1997. - S. 512-515. - ISBN 5-89501-008-3
- Ksanfomality L.V. Unknown Mercury // In the world of science. - 2008. - № 2.
Links
- MESSENGER mission website (eng.)
- Photos of Mercury taken by Messenger (eng.)
- Section about the BepiColombo mission on the JAXA website
- A. Levin. Iron Planet Popular Mechanics # 7, 2008
- "Nearest" Lenta.ru, October 5, 2009, photos of Mercury, taken by "Messenger"
- "Published new images of Mercury" Lenta.ru, November 4, 2009, on the approach of the Messenger and Mercury on the night of September 29-30, 2009
- "Mercury: Facts & Figures" NASA. Summary physical characteristics of the planet.
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