0.147 Earth
0.056 Earth
0.055 Earth
0.984 Earth
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 (Mariner 10 image)
Mercury- the planet closest to the Sun in the Solar System, orbits the Sun in 88 Earth days. Mercury is classified as an inner planet because its orbit is closer to the Sun than the main asteroid belt. After Pluto was deprived of its planetary status in 2006, Mercury acquired the title of the smallest planet in the solar system. Mercury's apparent magnitude ranges from −2.0 to 5.5, but it is not easily visible 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 hidden in the morning or evening dawn. The optimal time for observing the planet is morning or evening twilight during periods of its elongations (periods of Mercury's maximum distance 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 shortest. In mid-latitudes it is much more difficult to find Mercury and only during the period of the best elongations, and in high latitudes it is impossible at all.
Relatively little is known about the planet yet. 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 its physical characteristics, Mercury resembles the Moon and is heavily cratered. The planet has no natural satellites, but has a very thin atmosphere. The planet has a large iron core, which is the source of a magnetic field in its totality that is 0.1 of the Earth’s. Mercury's core makes up 70 percent of the planet's total volume. The temperature on the surface of Mercury ranges from 90 to 700 (−180 to +430 °C). The solar side heats up much more than the polar regions and the far side of the planet.
Despite its smaller radius, Mercury still exceeds in mass such satellites of the giant planets 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 oldest evidence of observations 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 Hesiod's time called Mercury "Στίλβων" (Stilbo, the Shining One). Until the 5th century BC. e. The Greeks believed that Mercury, visible in the evening and morning skies, were 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 ideas 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 fairly 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 at aphelion. The inclination of the orbit to the ecliptic plane is 7°. Mercury spends 87.97 days on one orbital revolution. The average speed of the planet's orbit is 48 km/s.
For a long time it was believed that Mercury constantly faces the Sun with the same side, and one revolution around its axis takes the same 87.97 days. Observations of details on the surface of Mercury, carried out at the limit of resolution, did not seem to contradict this. This misconception was due to the fact that the most favorable conditions for observing Mercury repeat 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 surface area was observed at different times planets. On the other hand, some astronomers believed that Mercury's day was approximately equal to Earth's. The truth was revealed only in the mid-1960s, when radar was carried out on Mercury.
It turned out that a Mercury sidereal day is equal to 58.65 Earth days, that is, 2/3 of a Mercury year. This commensurability of the periods of rotation and revolution of Mercury is a unique phenomenon for the Solar System. It is presumably explained by the fact that the tidal action of the Sun took away angular momentum and retarded the rotation, which was initially faster, until the two periods were related by an integer ratio. As a result, in one Mercury year, Mercury manages to rotate around its axis by one and a half revolutions. That is, if at the moment Mercury passes perihelion a certain point on its surface is facing exactly the Sun, then at the next passage of perihelion the exact opposite point on the surface will be facing the Sun, and after another Mercury year the Sun will again 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 this movement of the planet, “hot longitudes” can be distinguished on it - two opposite meridians, which alternately face the Sun during Mercury’s passage of perihelion, and which, because of this, are 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 its axis is practically constant, while the speed of orbital motion is constantly changing. In the orbital region near perihelion, for approximately 8 days, the speed of orbital motion exceeds the speed rotational movement. As a result, the Sun stops in the sky of Mercury and begins to move in the opposite direction - from west to east. This effect is sometimes called the Joshua effect, named 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° away from the “hot longitudes,” the Sun rises (or sets) twice.
It is also interesting that although Mars and Venus are the closest in orbit to Earth, it is Mercury that is most of the time the closest planet to Earth than any other (since the others move away more, not being so “tied” to the Sun).
physical characteristics
Comparative sizes of Mercury, Venus, Earth and Mars
Mercury is the smallest terrestrial planet. Its radius is only 2439.7 ± 1.0 km, which is smaller 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 Earth. Considering that the Earth is larger in size, the density value of Mercury indicates an increased content of metals in its depths. The acceleration of gravity on Mercury is 3.70 m/s². Second escape velocity- 4.3 km/s.
Kuiper Crater (just below center). Photo from MESSENGER spacecraft
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 whose impact formed the crater had a diameter of at least 100 km. The impact was so strong that the seismic waves, having passed through the entire planet and focused at the opposite point on the surface, led to the formation of a kind of intersected “chaotic” landscape here.
Atmosphere and physical fields
When the Mariner 10 spacecraft flew past Mercury, it was established that the planet had an extremely rarefied atmosphere, the pressure of which was 5 × 10 11 times less than the pressure of the Earth’s atmosphere. Under such conditions, atoms collide more often with the surface of the planet than with each other. It consists of atoms captured from the solar wind or knocked out from the surface by the solar wind - helium, sodium, oxygen, potassium, argon, hydrogen. The average lifetime of a certain atom in the atmosphere is about 200 days.
Mercury has 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 highest degree symmetrically, and its axis deviates only 2 degrees from the axis of rotation of the planet, which imposes a significant limitation on the range of theories explaining its origin.
Research
An image of a section of Mercury's surface taken by MESSENGER
Mercury is the least studied terrestrial planet. Only two devices were sent to study it. The first was Mariner 10, which flew past Mercury three times in -1975; the closest approach was 320 km. As a result, several thousand images were obtained, covering approximately 45% of the planet's surface. Further research from Earth showed the possibility of the existence of water ice in polar craters.
Mercury in art
- In Boris Lyapunov's science fiction story "Nearest to the Sun" (1956), Soviet cosmonauts land on Mercury and Venus for the first time to study them.
- Isaac Asimov's story "Mercury's Big Sun" (Lucky Starr series) takes place on Mercury.
- Isaac Asimov's stories "Runaround" and "The Dying Night", written in 1941 and 1956 respectively, describe Mercury with one side facing the Sun. Moreover, in the second story, the solution to the detective plot is based on this fact.
- In the science fiction novel The Flight of the Earth by Francis Karsak, along with the main plot, a scientific station for studying the Sun, located at the North Pole of Mercury, is described. Scientists live at a base located in the eternal shadow of deep craters, and observations are carried out from giant towers constantly illuminated by the luminary.
- In Alan Nurse's science fiction story "Across the Sunny Side", the main characters cross the side of Mercury facing the Sun. The story was written in accordance with the scientific views of its time, when it was assumed that Mercury was 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 is based on the power of water and ice.
- In Clifford Simak's science fiction story "Once Upon a Time 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
- Bronshten V. Mercury is closest to the Sun // Aksenova M.D. Encyclopedia for children. T. 8. Astronomy - M.: Avanta+, 1997. - P. 512-515. - ISBN 5-89501-008-3
- Ksanfomality L.V. Unknown Mercury // In the world of science. - 2008. - № 2.
Links
- Website about the MESSENGER mission (English)
- Photos of Mercury taken by Messenger (English)
- BepiColombo mission section on the JAXA website
- A. Levin. Iron Planet Popular Mechanics No. 7, 2008
- “The closest” Lenta.ru, October 5, 2009, photographs of Mercury taken by Messenger
- “New photographs of Mercury have been published” Lenta.ru, November 4, 2009, about the rapprochement of Messenger and Mercury on the night of September 29-30, 2009
- "Mercury: Facts & Figures" NASA. Summary physical characteristics of the planet.
Wikimedia Foundation. 2010.
Photo taken from the MESSENGER spacecraft.
The planet Mercury is the closest planet to the Sun. It is located at a distance of only 58 million km from our star (for comparison, from Earth to the Sun is 150 million km). Like all planets, It is named after a Roman god, in this case the Roman god of trade - just like the ancient Greek god Hermes.
Its diameter is only 4879 km, making it the smallest planet in solar system. It is even smaller than the moons Ganymede and Titan. But it has a metallic core that makes up almost half the volume of the planet. This gives it greater mass and stronger gravity than one would expect. On Mercury, your weight would be 38% of your weight on Earth.
Orbit
Mercury revolves around the Sun in a highly elongated elliptical orbit.
At its closest point, it approaches the Sun at 46 million km, and then moves away to 70 million km. It takes the planet only 88 days to orbit the Sun.
At first glance, Mercury is quite similar to our Moon. It has a surface covered with craters, as well as ancient lava flows. The largest crater is the Caloris Basin, almost 1300 km across. Like our Moon, it has no discernible atmosphere. But below the surface is very different from the Moon. It has a huge core of iron surrounded by a thick layer of mantle rocks and a thin crust. gravity on the planet is 1/3 of Earth's.
It rotates slowly around its axis, completing one revolution every 59 days.
Atmosphere
It is very rarefied and consists of captured particles of the Solar wind. Without an atmosphere, it cannot retain heat from the Sun. The side that faces the Sun heats up to a temperature of 450 °C, while the shadow side cools to -170 °C.
Study
BepiColumbo, which was launched to explore the planet
The first spacecraft to reach Mercury was Mariner 10, which flew past the planet in 1974. He managed to photograph about half of the planet's surface over several flybys. Then in 2004 NASA launched the MESSENGER spacecraft mission. At the moment, the spacecraft has entered orbit and is studying it in great detail.
If you want to see it without a telescope, it is difficult to do because the planet is in the bright rays of the Sun most time.
When visible, you can see it in the west just after sunset, or in the east before sunrise. In a telescope, the planet has phases like the Moon, depending on its position in its orbit.
Mercury is a hot planet
1. Mercury is the first planet in our solar system
2. Planetary movement
3. Physical characteristics
4. Surface
5. Atmosphere and physical fields
6. Research
7. Colonization of Mercury
8. Mercury in numbers
Mercury- the first from the Sun, the innermost and smallest planet in the Solar System, revolving around the Sun in 88 days. Mercury's apparent magnitude ranges from −2.0 to 5.5 and is not easily visible due to its very small angular distance from the Sun (maximum 28.3°). The planet can never be seen in the dark night sky: Mercury is always hidden in the morning or evening dawn. The optimal time for observing the planet is morning or evening twilight during periods of its elongations (periods of Mercury's maximum distance from the Sun in the sky, occurring several times a year). Relatively little is known about the planet yet. The Mariner 10 spacecraft, which studied Mercury in 1974-1975, managed to map only 40-45% of the surface. In January 2008, MESSENGER flew past Mercury and will enter orbit around the planet in 2011.
In its physical characteristics, Mercury resembles the Moon and is heavily cratered. The planet has no natural satellites, but has a very thin atmosphere. The planet has a large iron core, which is a source of a magnetic field in its totality constituting 0.1 of the Earth's. The temperature on the surface of Mercury ranges from 90 to 700 K (−180...430 °C). The sunflower side heats up much more than the polar regions and the far side of the planet.
The oldest evidence of observations 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, an analogue of the Greek Hermes and Babylonian Naboo. The astronomical symbol of Mercury is a stylized image of the winged helmet of the god Mercury from his caduceus. The ancient Greeks of Hesiod's time called Mercury "Στίλβων" (Stilbo, the Shining One). Until the 5th century BC. e. The Greeks believed that Mercury is two separate objects: one is visible only at sunrise, the other only in the evening at sunset. In ancient India, Mercury was called Buddha and Roginea. In Chinese, Japanese, Vietnamese and Korean, Mercury is called the Water Star (水星) (in accordance with the concept of the Five Elements). In Hebrew, the name of Mercury is Kokhav Hama (כוכב חמה) ("Solar Planet"). Despite smaller radius, Mercury still exceeds in mass such satellites of the giant planets as Ganymede and Titan.
Planet movement
Mercury moves around the Sun in a fairly 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, at aphelion - 69.7 million km. The inclination of the orbit to the ecliptic plane is 7°. Mercury spends 87.97 days on one orbital revolution. The average speed of the planet's orbit is 48 km/s.
For a long time it was believed that Mercury constantly faces the Sun with the same side, and one revolution around its axis takes the same 87.97 days. Observations of details on the surface of Mercury, carried out at the limit of resolution, did not seem to contradict this. This misconception was due to the fact that the most favorable conditions for observing Mercury repeat 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 surface area was observed at different times planets. On the other hand, some astronomers believed that Mercury's day was approximately equal to Earth's. The truth was revealed only in the mid-1960s, when radar was carried out on Mercury. It turned out that a Mercury sidereal day is equal to 58.65 Earth days, that is, 2/3 of a Mercury year. This is a unique phenomenon for the Solar System. The phenomenon of commensurability between the periods of rotation and revolution of Mercury is apparently explained by the fact that the tidal influence of the Sun carried away the angular momentum and slowed down the rotation, which was initially faster, until both periods were in an integer ratio. As a result, in one Mercury year, Mercury manages to rotate around its axis by one and a half revolutions. That is, if at the moment Mercury passes perihelion a certain point on its surface is facing exactly the Sun, then at the next passage of perihelion the exact opposite point on the surface will be facing the Sun, and after another Mercury year the Sun will again 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 this movement of the planet, “hot longitudes” can be distinguished on it - two opposite meridians, which alternately face the Sun during Mercury’s passage of perihelion, and which, because of this, are 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 its axis is practically constant, while the speed of orbital motion is constantly changing. In the orbital region near perihelion, for approximately 8 days the speed of orbital motion exceeds the speed of rotational motion. As a result, the Sun stops in the sky of Mercury and begins to move in the opposite direction - from west to east. This effect is sometimes called the Joshua effect, named after biblical hero, who stopped the movement of the Sun (Joshua, X, 12-13). For an observer at longitudes 90° away from the “hot longitudes,” the Sun rises (or sets) twice.
It's also interesting that while Mars and Venus are the closest planets to Earth in terms of orbits, Mercury is the closest planet to Earth most of the time than any other (since the others move further away without being as "attached" to the Sun).
physical characteristics
Mercury is the smallest terrestrial planet. 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 3.3×1023 kg. The average density of Mercury is quite high - 5.43 g/cm³, which is only slightly less than the density of Earth. Considering that the Earth is larger in size, the density value of Mercury indicates an increased content of metals in its depths. Acceleration free fall on Mercury it is 3.70 m/s². The second escape velocity is 4.3 km/s.
The proximity to the Sun and the rather slow rotation of the planet, as well as the lack of an atmosphere, lead to the fact that Mercury experiences the most dramatic temperature changes in the Solar System. The average temperature of its daytime surface is 623 K, and at night it is only 103 K. The minimum temperature on Mercury is 90 K, and the maximum, reached at noon at “hot longitudes”, is 700 K.
Despite these conditions, there have recently been suggestions that ice may exist on the surface of Mercury. Radar studies of the planet's circumpolar regions have shown the presence of a substance there that strongly reflects radio waves, the most likely candidate for which is ordinary water ice. Entering the surface of Mercury when comets hit it, water evaporates and travels around the planet until it freezes in the polar regions at the bottom of deep craters, where the Sun never looks, and where ice can persist for an almost unlimited time.
Until recently, it was assumed that in the bowels of Mercury there is a metallic core with a radius of 1800-1900 km containing 60% of the planet’s mass, surrounded by a silicate shell 500-600 km thick, since the Mariner 10 spacecraft discovered a weak magnetic field, and it was believed that a planet with such small size cannot have a liquid core. But in 2007, Jean-Luc Margot's group summed up the results of five years of radar observations of Mercury, during which variations in the planet's rotation were noticed that were too large for a model with a solid core.
Surface
The surface of Mercury is in many ways reminiscent of the Moon - it is dotted with many craters. The density of craters varies in different areas. It is assumed that the more densely dotted areas with craters are more ancient, and the less densely dotted ones are younger, formed when the old surface was flooded with lava. At the same time, large craters are less common on Mercury than on the Moon. The largest crater on Mercury is named after the great German composer Beethoven, its diameter is 625 km. However, the similarity is incomplete - formations are visible on Mercury that are not found on the Moon. An important difference between the mountainous landscapes of Mercury and the Moon is the presence on Mercury of numerous jagged slopes stretching for hundreds of kilometers - scarps. A study of their structure showed that they were formed during compression that accompanied the cooling of the planet, as a result of which the surface of Mercury decreased by 1%. 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 was no erosion of the surface; the latter almost completely excludes the possibility of the existence of any significant atmosphere.
During research carried out by the MESSENGER probe, over 80% of the surface of Mercury was photographed and it was revealed that it is homogeneous, which distinguishes Mercury from the Moon or Mars, in which one hemisphere is sharply different from the other.
One of the most noticeable features of the surface of Mercury is the Plain of Heat (“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 whose impact formed the crater had a diameter of at least 100 km. The impact was so strong that the seismic waves, having passed through the entire planet and focused at the opposite point on the surface, led to the formation of a kind of rugged “chaotic” landscape here.
Atmosphere and physical fields
When the Mariner 10 spacecraft flew past Mercury, it was established that the planet had an extremely rarefied atmosphere, the pressure of which was 5 × 1011 times less than the pressure of the Earth’s atmosphere. Under such conditions, atoms collide more often with the surface of the planet than with each other. It consists of atoms captured from the solar wind or knocked out from the surface by the solar wind - 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 whose strength is 300 times less than the Earth's magnetic field. Mercury's magnetic field has a dipole structure and is highly symmetrical, and its axis deviates only 2 degrees from the planet's rotation axis, which imposes a significant limitation on the range of theories explaining its origin.
Research
Mercury is the least studied terrestrial planet. Only two devices were sent to study it. The first was Mariner 10, which in 1974-1975. flew past Mercury three times; the closest approach was 320 km. As a result, several thousand images were obtained, covering approximately 45% of the planet's surface. Further research from Earth showed the possibility of the existence of water ice in polar craters.
NASA is currently conducting a second mission to Mercury called MESSENGER. The device was launched on August 3, 2004. On January 14, 2008, the device made its first flyby of its target - Mercury. To enter orbit around the planet on March 18, 2011, the device will have to perform two more gravity assist maneuvers past Mercury on October 6, 2008 and September 29, 2009. MESSENGER also completed one flyby of Earth in 2005 (February 8), and two flybys of Venus: October 24, 2006 and June 5, 2007, during which he checked the equipment.
The European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) are developing the BepiColombo mission, consisting of two spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The European MPO will explore Mercury's surface and depths, while the Japanese MMO will observe the planet's magnetic field and magnetosphere. BepiColombo is scheduled to launch in 2013, and in 2019 it will reach the orbit of Mercury, where it will split into two components.
The development of electronics and computer science has made it possible to ground-based observations of Mercury using CCD radiation receivers and subsequent computer processing of images. One of the first series of observations of Mercury with CCD receivers was carried out in 1995-2002 by Johan Varell at the observatory on the island of La Palma on a half-meter solar telescope. Varell selected the best shots without using computer information. The reduction began to be applied at the Abastumani Astrophysical Observatory to series of photographs of Mercury received on November 3, 2001, as well as at the Skinakas Observatory of the University of Heraklion to series from May 1-2, 2002; To process the observation results, the correlation combination method was used. The resulting resolved image of the planet was similar to the Mariner-10 photomosaic; the outlines of small formations measuring 150-200 km in size were repeated. This is how a map of Mercury was compiled for longitudes 210-350°.
Colonization of Mercury
Like the Moon, Mercury does not have a dense atmosphere, is located relatively close to the Sun and rotates slowly around its axis, which has a very slight tilt. Therefore, due to the relatively large similarities, it is believed that the colonization of Mercury can be carried out using essentially the same technologies, approaches and equipment as the colonization of the Moon.
Despite its proximity to the Sun, the existence of ice caps at Mercury's poles was theoretically predicted. This makes the poles the most suitable place to establish a colony. In addition, in the region of the poles, temperature fluctuations during the change of day and night will not be as noticeable as in any other place on the surface of Mercury.
Being the closest planet to the Sun, Mercury has enormous reserves of solar energy. The amount of incoming solar energy per unit area here is 9.13 kW/m² (for the Earth and the Moon - 1.36 kW/m²). Since the inclination of Mercury's axis to the ecliptic axis is insignificant (approximately 0.01°), there is a possibility that there are peaks of eternal light at the heights of the poles. Even if they are not there, they can be obtained on high towers. In addition, it is possible to build a closed ring of solar power plants in the area of the poles, capable of providing a continuous supply of energy.
It is believed that Mercury's soil contains a large reserve of helium-3, which could become an important source of clean energy on Earth and a decisive factor in the development of the solar system's economy in the future. Additionally, Mercury may have large deposits of rich ore available for mining. This ore can later be used to build space stations.
Mercury is larger than the Moon (Mercury's diameter is 4879 km, the Moon's is 3476 km) and has a higher density due to its massive iron core. As a result, the acceleration due to gravity on Mercury is 0.377 g, which is more than twice that on the Moon (0.1654 g) and is equal to the acceleration due to gravity on the surface of Mars. Due to the fact that prolonged exposure to reduced gravity has a detrimental effect on human health, Mercury is more attractive as an object for long-term stay than the Moon
The almost complete absence of an atmosphere, extreme proximity to the Sun and a long day (176 Earth days) can become serious obstacles to the settlement of Mercury. Even with ice at the planet's poles, the presence of light elements necessary for life seems very unlikely. They will need to be imported. In addition, in the vicinity of Mercury, the gravitational force of the Sun is very strong, which requires more power to travel to and from Mercury than for other planets. The gravitational influence of Venus can be used to reach Mercury.
Mercury in numbers
Orbital characteristics
Aphelion - 69,816,927 km
Perihelion - 46,001,210 km
Semi-major axis - 57,909,068 km
Orbital eccentricity - 0.20530294
Sidereal period - 87.969098 days
Synodic period - 115.88 days
Orbital speed - 47.87 km/s
Average anomaly - 174.795884°
Inclination - 3.38° (o.c.e.)
Longitude of the ascending node - 48.330541°
Periapsis argument - 29.124279°
Satellites - no
physical characteristics
Average radius - 2439.7 ± 1.0 km
Surface area - 7.48×107 km²
Compression< 0,0006
Volume 6.083×1010 km³
Weight 3.3022×1023 kg
Average density 5.427 g/cm³
Gravity at the equator 3.7 m/s²
Second escape velocity 4.25 km/s
Rotation period (around its axis) 58.646 days
Rotation speed at the equator 10.892 km/h
The inclination of the planet's rotation axis is 0.01°
Right ascension at the North Pole 18 hours 44 minutes 2 seconds
Declination 61.45°
Albedo 0.119 (Bond)
Temperature
Minimum 100 K (-173 °C)
Average 340 K (67 °C)
Maximum 700 K (427 °C)
Atmospheric composition
Compound:
31.7% Potassium
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
Characteristics of the planet:
- Distance from the Sun: 57.9 million km
- Planet diameter: 4878 km
- Day on the planet: 58 days 16 hours*
- Year on the planet: 88 days*
- t° on the surface: from -180°C to +430°C
- Atmosphere: almost not present
- Satellites: doesn't have
* period of rotation around its own axis (in Earth days)
**period of orbit around the Sun (in Earth days)
Mercury is the eighth largest planet and 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 the Earth’s, the only difference is in size. If the earth's core occupies only 17% of the planet's volume, then Mercury's occupies 42% of the volume.
Around the core there is a layer of mantle - 500-700 kilometers of silicate rock. The next layer is the crust, which is approximately 100-300 kilometers thick. The top layer of the planet has a lot of damage, most scientists adhere to the theory that they were caused by the slow cooling of Mercury.
Atmosphere and surface
The atmosphere of Mercury is very thin and almost equal to a vacuum. Compound:
- hydrogen (70 atoms per 1 cm³);
- helium (4,500 atoms per 1 cm³).
Due to the almost zero atmosphere and proximity to the Sun, the temperature on the surface of the planet fluctuates between -180....+440 °C. The surface resembles the lunar surface - many craters (from collisions with asteroids), and mountains up to 4 km high (lunar ones can be one and a half times higher).
Unlike the Earth's satellite, on the far side of Mercury there are swellings that were formed under the influence of solar tides. There are also high ledges, whose length can reach several hundred kilometers.
The name of the planet was given by the ancient Romans, who revered the god Mercury as the patron of thieves, travelers and traders. However, it is believed that the first planet from the Sun was known as early as 3000 BC. (from the time of the Samaritans).
IN Ancient Greece she was called by two names at once - Apollo (the god of sunlight, patron of the arts and science) in the morning and Hermes (the nimble 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 movement of Mercury across the sky, and all because of the anomalous precession of its orbit. Newtonian mechanics was in no way suitable for explaining 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 influenced its orbit. It became possible to correctly predict the movement of the planet only after Einstein’s discovery of it. General Theory Relativity.
Exploring the planet
The study of Mercury is very complicated due to its close location to the Sun, from the American Hubble telescope It is impossible to get high-quality pictures.
Only one interplanetary station approached the planet - Mariner 10, which made three flybys in 1974-1975. It was possible to map only 45% of the planet.
Radar observations were also carried out, but these data relate more to theory than to hard facts. Thus, a similar study showed the presence of frozen water at the north pole of Mercury (Mariner did not map this area).
Mercury is the first planet of the solar system. Not long ago she occupied almost last place among all 9 planets in size. But, as we know, nothing lasts forever under the Moon. In 2006, Pluto lost its status as a planet due to its oversized size. It came to be called a dwarf planet. Thus, Mercury is now at the end of a series of cosmic bodies that cut countless circles around the Sun. But this is about sizes. In relation to the Sun, the planet is the closest - 57.91 million km. This is the average value. Mercury rotates in an overly elongated orbit, the length of which is 360 million km. That is why it is sometimes further from the Sun, sometimes, on the contrary, closer to it. At perihelion (the point of its orbit closest to the Sun), the planet approaches the blazing star at 45.9 million km. And at aphelion (the farthest point of the orbit), the distance to the Sun increases and is equal to 69.82 million km.
Regarding the Earth, the scale is slightly different. Mercury from time to time approaches us up to 82 million km or diverges to a distance of 217 million km. The smallest number does not mean that the planet can be examined carefully and for a long time in a telescope. Mercury deviates from the Sun at an angular distance of 28 degrees. It follows that this planet can be observed from Earth just before dawn or after sunset. You can see it almost at the horizon line. You can also see not the whole body, but only half of it. Mercury rushes through orbit at a speed of 48 km per second. The planet completes a full revolution around the Sun in 88 Earth days. The value that shows how different the orbit is from the circle is 0.205. The takeoff between the orbital plane and the equatorial plane is 3 degrees. This suggests that the planet is characterized by minor seasonal changes. Mercury is a terrestrial planet. This also includes Mars, Earth and Venus. They all have very high density. The diameter of the planet is 4880 km. It’s a shame to realize that even some of the planets’ satellites have surpassed it here. The diameter of the largest satellite, Ganymede, which orbits Jupiter, is 5262 km. Titan, the satellite of Saturn, has an equally impressive appearance. Its diameter is 5150 km. The diameter of Callisto (a satellite of Jupiter) is 4820 km. The Moon is the most popular satellite in the Solar System. Its diameter is 3474 km.
Earth and Mercury
It turns out that Mercury is not so unpresentable and nondescript. Everything is learned by comparison. The small planet is quite inferior in size to the Earth. Compared to our planet, this small cosmic body looks like a fragile creature. Its mass is 18 times less than that of the Earth, and its volume is 17.8 times. The area of Mercury lags behind the area of the Earth by 6.8 times.
Features of Mercury's orbit
As mentioned above, the planet makes a full revolution around the Sun in 88 days. It rotates around its axis in 59 Earth days. The average speed is 48 km per second. In some parts of its orbit, Mercury moves slower, in others faster. Its maximum speed at perihelion is 59 km per second. The planet is trying to pass the closest part to the Sun as quickly as possible. At aphelion, Mercury's speed is 39 km per second. The interaction of speed around the axis and speed along the orbit gives a damaging effect. For 59 days, any part of the planet is in the same position to the starry sky. This portion returns to the Sun after 2 Mercury years or 176 days. From this it turns out that a solar day on the planet is equal to 176 days. At perihelion it is observed interesting fact. Here the speed of rotation along the orbit becomes greater than the movement around the axis. This is how the effect of Joshua (the leader of the Jews who stopped the Sun) arises at longitudes that are turned towards the luminary.
Sunrise on the planet
The sun stops and then starts moving in the opposite direction. The luminary tends to the East, completely ignoring its destined western direction. This continues for 7 days until Mercury passes the closest part of its orbit to the Sun. Then its orbital speed begins to decrease, and the movement of the Sun slows down. At the point where the velocities coincide, the luminary stops. A little time passes, and it begins to move in the opposite direction - from east to west. Regarding longitudes, the picture is even more surprising. If people lived here, they would watch two sunsets and two sunrises. Initially, the Sun would have risen, as expected, in the east. It would have stopped in a moment. Afterwards it began to move backwards and disappear beyond the horizon. After 7 days, it would shine again in the east and make its way to the highest point in the sky without obstacles. Such striking features of the planet’s orbit became known in the 60s. Previously, scientists believed that it is always turned to the Sun with one side, and moves around its axis at the same speed as around the yellow star.
Structure of Mercury
Until the first half of the 70s, people knew little about its structure. In 1974, in March, the interplanetary station Mariner 10 flew 703 km from the planet. She repeated her maneuver in September of the same year. Now its distance to Mercury was 48 thousand km. And in 1975, the station made another orbit at a distance of 327 km. It is noteworthy that the equipment detected a magnetic field. It was not a powerful formation, but compared to Venus it looked quite significant. Mercury's magnetic field is 100 times inferior to Earth's. Its magnetic axis does not coincide with the axis of rotation by 2 degrees. The presence of such a formation confirms that this object has a core, where this very field is created. Today there is such a scheme for the structure of the planet - Mercury has a hot iron-nickel core and a silicate shell that surrounds it. The core temperature is 730 degrees. Large core. It contains 70% of the mass of the entire planet. The diameter of the core is 3600 km. The thickness of the silicate layer is within 650 km.
Surface of the planet
The planet is dotted with craters. In some places they are located very densely, in others there are very few of them. The largest crater is Beethoven, its diameter is 625 km. Scientists suggest that the flat terrain is younger than the one dotted with many craters. It was formed due to lava emissions, which covered all the craters and made the surface flat. Here is the most great education, which is called the Plain of Heat. This is an ancient crater with a diameter of 1300 km. It is surrounded by a mountainous ring. It is believed that lava eruptions flooded this place and made it almost invisible. Opposite this plain there are many hills that can reach 2 km in height. The lowlands are narrow. Apparently, a large asteroid that fell on Mercury provoked a shift in its interior. In one place a large dent was left, and on the other side the crust rose and thus formed rock displacements and faults. Something similar can be observed in other places on the planet. These formations already have a different geological history. Their shape is wedge-like. The width reaches tens of kilometers. It seems that this rock, which was squeezed out under enormous pressure from the deep bowels.
There is a theory that these creations arose when the temperature conditions of the planet decreased. The core began to cool and at the same time contract. Thus, the top layer also began to decrease. Shifts of the cortex were provoked. This is how this peculiar landscape of the planet was formed. Now the temperature regimes of Mercury also have certain specifics. Taking into account the fact that the planet is close to the Sun, the conclusion follows: the surface that faces the yellow star has too high a temperature. Its maximum can be 430 degrees (at perihelion). At aphelion, it is correspondingly cooler – 290 degrees. In other parts of the orbit, the temperature fluctuates between 320-340 degrees. It is easy to guess that at night the situation here is completely different. At this time, the temperature remains at minus 180. It turns out that in one part of the planet there is terrible heat, and in another at the same time there is terrible cold. It is an unexpected fact that the planet has reserves of water ice. It is found at the bottom of large craters in polar points. The sun's rays do not penetrate here. Mercury's atmosphere contains 3.5% water. Comets deliver it to the planet. Some collide with Mercury when approaching the Sun, and remain here forever. The ice melts into water, which evaporates into the atmosphere. At cold temperatures, it settles to the surface and turns back into ice. If it ends up at the bottom of a crater or at a pole, it freezes and never returns to a gaseous state. Since there are temperature differences here, the conclusion follows: cosmic body no atmosphere. More precisely, there is a gas cushion, but it is too rarefied. Main chemical element The atmosphere of this planet is helium. It is brought here by the solar wind, a stream of plasma that flows from the solar corona. Its main components are hydrogen and helium. The first is present in the atmosphere, but in a smaller proportion.
Research
Although Mercury is not at a great distance from Earth, its study is quite difficult. This is due to the peculiarities of the orbit. This planet is very difficult to see in the sky. Only by observing it up close can you get a complete picture of the planet. In 1974, such an opportunity arose. As already mentioned, this year the Mariner 10 interplanetary station was near the planet. She took photographs and used them to map almost half of Mercury's surface. In 2008, the Messenger station paid attention to the planet. Of course, the planet will continue to be studied. We will see what surprises she will present. After all, space is so unpredictable, and its inhabitants are mysterious and secretive.
Facts worth knowing about the planet Mercury:
It is the smallest planet in the solar system.
A day here is 59 days, and a year is 88.
Mercury is the planet closest to the Sun. Distance – 58 million km.
It is a rocky planet that belongs to earth group. Mercury has a heavily cratered, rugged surface.
Mercury has no satellites.
The planet's exosphere consists of sodium, oxygen, helium, potassium and hydrogen.
There is no ring around Mercury.
There is no evidence of life on the planet. Daytime temperatures reach 430 degrees and drop to minus 180.
From the closest point to the yellow star on the surface of the planet, the Sun appears 3 times larger than from Earth.