Rotation of Mercury. Mercury: fast and hot How many days does Mercury take to revolve around the sun?

The distance from Mercury to the Sun is 58 million km.

A year on Mercury lasts 88 days, during which time it completes a full revolution around the Sun. But a “day” on Mercury lasts almost two - it rotates very slowly.

The surface of Mercury is covered like the moon, and consists of very rarefied helium.

Primary data about Mercury

Greek astronomers initially called the planet Stilbon (“Brilliant”), and closer to the turn of the new era, the name was assigned to it in honor of the Greek and Roman god - the patron of magic and, the messenger of the Olympian gods and the guide of the souls of the dead to the other world.

At the same time, no traces were noticed, except for many kilometers of scarps - ledges that were formed as a result of shifts of some sections of the surface relative to others.

However, the cause of scarps may not be volcanoes at all. Its proximity to the hot Sun, the planet's slow rotation and the almost complete absence of an atmosphere mean that Mercury experiences the most dramatic temperature changes in the Solar System, reaching 600°C.

So, at midnight the surface cools to -180°, and at noon it heats up to +500°. It is difficult to find ones that can withstand such changes for a long time.

However, the resemblance to the Moon is incomplete. Large craters are much less common on Mercury than on the Moon. The largest of them is 625 km across and named after the German composer Ludwig van Beethoven.

There are no signs of erosion of the surface layers, which means that in the entire history of Mercury it has never had a dense atmosphere.

The brightest point on the planet's surface is Kuiper Crater, 60 km in diameter. This may be due to the fact that it was formed quite recently and is not covered with layers of crushed rocks.

The commensurability of the length of the day and year on Mercury is exceptional for the Solar System and leads to unique phenomena. Mercury's orbit is quite elongated, and according to Kepler, in those areas that are closer to the Sun, the planet moves faster.

And the rotation of Mercury around its axis has a constant speed, and therefore either “lags behind” or “leads” the moments of passage.

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" - after the biblical figure who stopped the movement of the Sun in order to end the battle before sunset.

Mercury– the first planet of the solar system: description, size, mass, orbit around the Sun, distance, characteristics, interesting facts, history of study.

Mercury- the first planet from the Sun and the smallest planet in the Solar System. This is one of the most extreme worlds. It received its name in honor of the messenger of the Roman gods. It can be found without the use of instruments, which is why Mercury is noted in many cultures and myths.

However, it is also a very mysterious object. Mercury can be observed in the morning and evening in the sky, and the planet itself has its own phases.

Interesting facts about the planet Mercury

Let's find out more interesting facts about the planet Mercury.

A year on Mercury lasts only 88 days

• One solar day (the interval between noon) covers 176 days, and a sidereal day (axial rotation) covers 59 days. Mercury is endowed with the greatest orbital eccentricity, and its distance from the Sun is 46-70 million km.

It is the smallest planet in the system

• Mercury is one of the five planets that can be found without the use of instruments. At the equator it extends over 4879 km.

It ranks second in density

• Each cm 3 is endowed with an indicator of 5.4 grams. But the Earth comes first because Mercury is represented by heavy metals and rocks.

There are wrinkles

• As the iron planetary core cooled and contracted, the surface layer became wrinkled. They can stretch for hundreds of miles.

There is a molten core

• Researchers believe that Mercury's iron core is capable of remaining in a molten state. Usually on small planets it quickly loses heat. But now they think that it contains sulfur, which lowers the melting point. The core covers 42% of the planetary volume.

In second place in terms of heat

• Although Venus lives further away, its surface consistently maintains the highest surface temperature due to the greenhouse effect. The daytime side of Mercury warms up to 427°C, while the nighttime temperature drops to -173°C. The planet lacks an atmospheric layer and is therefore unable to provide uniform distribution of heating.

Most Cratered Planet

• Geological processes help planets renew their surface layer and smooth out crater scars. But Mercury is deprived of such an opportunity. All its craters are named after artists, writers and musicians. Impact formations exceeding 250 km in diameter are called basins. The largest is the Heat Plain, which stretches for 1550 km.

It was visited by only two devices

• Mercury is too close to the Sun. Mariner 10 flew around it three times in 1974-1975, imaging slightly less than half of the surface. MESSENGER went there in 2004.

The name was given in honor of the envoy to the Roman divine pantheon

• The exact date of discovery of the planet is unknown, because the Sumerians wrote about it in 3000 BC.

There is an atmosphere (I think)

• Gravity is only 38% of Earth's, but this is not enough to maintain a stable atmosphere (it is destroyed by solar winds). The gas comes out, but it is replenished by solar particles and dust.

Size, mass and orbit of the planet Mercury

With a radius of 2440 km and a mass of 3.3022 x 10 23 kg Mercury considered the smallest planet in the solar system. It is only 0.38 times the size of Earth. It is also inferior in parameters to some satellites, but in terms of density it is in second place after the Earth - 5.427 g/cm 3 . The bottom photo shows a comparison of the sizes of Mercury and Earth.

This is the owner of the most eccentric orbit. Mercury's distance from the Sun can vary from 46 million km (perihelion) to 70 million km (aphelion). This may also change the nearest planets. The average orbital speed is 47,322 km/s, so it takes 87,969 days to complete the orbital path. Below is a table of characteristics of the planet Mercury.

The rotation speed of the axis is 10.892 km/h, so a day on Mercury lasts 58.646 days. This suggests that the planet is in a 3:2 resonance (3 axial rotations per 2 orbital rotations).

The eccentricity and slowness of rotation mean that the planet takes 176 days to return to its original point. So one day on the planet is twice as long as a year. It also has the lowest axial tilt - 0.027 degrees.

Composition and surface of the planet Mercury

Composition of Mercury 70% represented by metal and 30% silicate materials. It is believed that its core covers approximately 42% of the total volume of the planet (for the Earth - 17%). Inside there is a core of molten iron, around which a silicate layer (500-700 km) is concentrated. The surface layer is the crust with a thickness of 100-300 km. On the surface you can see a huge number of ridges that stretch for kilometers.

Compared to other planets in the solar system, Mercury's core contains the largest amount of iron. It is believed that Mercury used to be much larger. But due to an impact with a large object, the outer layers collapsed, leaving the main body.

Some believe that the planet may have appeared in a protoplanetary disk before solar energy became stable. Then it should be twice as massive as the current state. When heated to 25,000-35,000 K, most of the rock could simply evaporate. Study the structure of Mercury in the photo.

There is one more assumption. The solar nebula could lead to an increase in particles that attacked the planet. Then the lighter ones moved away and were not used in the creation of Mercury.

When viewed from afar, the planet resembles the earth's satellite. The same crater landscape with plains and traces of lava flows. But here there is a greater variety of elements.

Mercury formed 4.6 billion years ago and was bombarded by an army of asteroids and debris. There was no atmosphere, so the impacts left noticeable marks. But the planet remained active, so lava flows created plains.

The sizes of the craters range from small pits to basins hundreds of kilometers wide. The largest is Kaloris (Zary Plain) with a diameter of 1550 km. The impact was so strong that it led to a lava eruption on the opposite planetary side. And the crater itself is surrounded by a concentric ring 2 km high. About 15 large crater formations can be found on the surface. Take a close look at the diagram of Mercury's magnetic field.

The planet has a global magnetic field reaching 1.1% of Earth's strength. It is possible that the source is a dynamo, reminiscent of our Earth. It is formed due to the rotation of a liquid core filled with iron.

This field is enough to resist stellar winds and form a magnetospheric layer. Its strength is enough to hold plasma from the wind, causing surface weathering.

Atmosphere and temperature of the planet Mercury

Due to its proximity to the Sun, the planet warms up too much, so it is not able to preserve the atmosphere. But scientists noted a thin layer of variable exosphere, represented by hydrogen, oxygen, helium, sodium, water vapor and potassium. The overall pressure level is approaching 10-14 bar.

Without an atmospheric layer, solar heat does not accumulate, so serious temperature fluctuations are observed on Mercury: on the sunny side - 427 ° C, and on the dark side it drops to -173 ° C.

However, the surface contains water ice and organic molecules. The fact is that the polar craters differ in depth and do not receive direct sunlight. It is believed that 10 14 – 10 15 kg of ice can be found at the bottom. There is no exact data yet on where the ice came from on the planet, but it could be a gift from fallen comets or it may be due to the degassing of water from the planetary interior.

History of the study of the planet Mercury

A description of Mercury is not complete without a history of research. This planet is accessible for observation without the use of instruments, therefore it appears in myths and ancient legends. The first records were found in the Mul Apin tablet, which serves as astronomical and astrological Babylonian records.

These observations were made in the 14th century BC. and they talk about the “dancing planet” because Mercury moves the fastest. In Ancient Greece it was called Stilbon (translated as “shine”). It was the messenger of Olympus. Then the Romans adopted this idea and gave it a modern name in honor of their pantheon.

Ptolemy mentioned several times in his works that planets are capable of passing in front of the Sun. But he did not include Mercury and Venus as examples because he considered them too small and inconspicuous.

The Chinese called it Chen Xin (“Hour Star”) and associated it with water and northern orientation. Moreover, in Asian culture, such an idea of ​​the planet is still preserved, which is even written down as the 5th element.

For the Germanic tribes, there was a connection with the god Odin. The Mayans saw four owls, two of which were responsible for the morning, and the other two for the evening.

One of the Islamic astronomers wrote about the geocentric orbital path back in the 11th century. In the 12th century, Ibn Bajya noted the transit of two tiny dark bodies in front of the Sun. Most likely he saw Venus and Mercury.

The Indian astronomer of Kerala Somayaji in the 15th century created a partial heliocentric model where Mercury orbited the Sun.

The first survey through a telescope dates back to the 17th century. Galileo Galilei did it. He then carefully studied the phases of Venus. But his device did not have enough power, so Mercury was left without attention. But the transit was noted by Pierre Gassendi in 1631.

Orbital phases were noticed by Giovanni Zupi in 1639. This was an important observation because it confirmed the rotation around the star and the correctness of the heliocentric model.

More accurate observations in the 1880s. contributed by Giovanni Schiaparelli. He believed that the orbital path took 88 days. In 1934, Eugios Antoniadi created a detailed map of the surface of Mercury.

Soviet scientists managed to intercept the first radar signal in 1962. Three years later, the Americans repeated the experiment and fixed the axial rotation at 59 days. Conventional optical observations failed to provide new information, but interferometers revealed the chemical and physical characteristics of the subsurface layers.

The first in-depth study of surface features was carried out in 2000 by the Mount Wilson Observatory. Most of the map was compiled using the Arecibo radar telescope, where the extension reaches 5 km.

Exploration of the planet Mercury

Until the first flight of unmanned vehicles, we did not know much about morphological characteristics. Mariner was the first to go to Mercury in 1974-1975. He zoomed in three times and took a series of large-scale photographs.

But the device had a long orbital period, so with each approach it approached the same side. So the map made up only 45% of the entire area.

At the first approach, it was possible to detect a magnetic field. Subsequent approaches showed that it strongly resembles the Earth's, deflecting stellar winds.

In 1975, the device ran out of fuel and we lost contact. However, Mariner 10 can still orbit the Sun and visit Mercury.

The second messenger was MESSENGER. He had to understand density, magnetic field, geology, core structure and atmospheric features. To do this, special cameras were installed to guarantee higher resolution, and spectrometers marked the constituent elements.

MESSENGER launched in 2004 and has completed three flybys since 2008, making up for the territory lost by Mariner 10. In 2011, it moved to an elliptical planetary orbit and began filming the surface.

After this, the next year-long mission started. The last maneuver took place on April 24, 2015. After this, the fuel ran out, and on April 30 the satellite crashed onto the surface.

In 2016, ESA and JAXA teamed up to create BepiColombo, which is due to reach the planet in 2024. It has two probes that will study the magnetosphere as well as the surface in all wavelengths.

Mercury is the first planet of the solar system. Not so long ago it ranked almost last 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. All of them have a 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. An interesting fact is observed at perihelion. 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 largest formation, 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 is a rock that 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 at 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 temperature differences are observed here, the conclusion follows: the cosmic body has no atmosphere. More precisely, there is a gas cushion, but it is too rarefied. The main chemical element in 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.

This is a rocky planet that belongs to the terrestrial 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.

Mercury is the closest planet to the Sun.
This planet got its name in honor of the god Mercury - the messenger of the gods, the patron of trade and travelers - because of its high speed of rotation around the Sun.
Mercury moves faster than all the planets - 174,000 km/h.
It makes a complete revolution around the Sun in 88 (87.97) Earth days in an elongated orbit, sometimes moving away from the Sun by 70 million km, while the shortest distance to the Sun is 46 million km.

And the duration of a sidereal day on Mercury (one revolution around its axis) is 58.65 Earth days.
Quickly rushing along its orbit, Mercury lazily turns around its axis. In one Mercury year, the planet manages to rotate around its axis by one and a half revolutions.

The average time interval between the two upper culminations of the Sun on this planet is 176 days. Interestingly, when it is near perihelion (closest distance from the Sun), the Sun for an observer on the surface of the planet can move in the opposite direction for 8 days.

Distance from Mercury to Earth varies from 82 to 217 million km.
The planet is visible to the naked eye.
Over the course of several days, when observed from Earth, Mercury changes its position relative to the Sun from the west (morning visibility) to the east (evening visibility).

Mercury's rotation axis and its orbit are practically perpendicular.
Mercury is so small that its mass (3.3·1023 kg) is 1/20 the mass of the Earth.
The radius of Mercury is only 2439.7 ± 1.0 km, which is less than the radius of Jupiter's moon Ganymede and Saturn's moon Titan.
The proximity to the Sun and the rather slow rotation of the planet, as well as the extremely thin atmosphere, lead to the fact that Mercury experiences the most dramatic temperature changes in the Solar System.
The temperature on the sunny side of the planet is 420 °C.
Temperatures on the dark side drop to -190°C.
The average density of Mercury is 5.43 g/cm³ (slightly less than the density of the Earth). This density indicates an increased content of metals in its depths.
The planet has an almost spherical shape. The acceleration of gravity on its surface is g = 3.72 m/s2.

Mercury, along with Venus, Earth and Mars, belongs to the terrestrial planets.

When the Mariner 10 spacecraft transmitted the first close-up images of Mercury, astronomers threw up their hands: there was a second Moon in front of them! The surface of Mercury turned out to be dotted with a grid of craters of different sizes, just like the surface of the Moon. Their size distribution was also similar to that of the Moon. Most of the craters were formed as a result of falling meteorites.
Mercury is very similar to the Moon.
It turned out that on Mercury, like on the Moon, there are two main types of terrain - analogues of lunar continents and seas. Continental areas are the most ancient geological formations of Mercury, consisting of areas dotted with craters, mountainous and hilly formations, and intercrater plains. Analogues of the lunar seas are considered to be the smooth plains of Mercury, which are younger in age than the continents, somewhat darker than the continental formations, but still not as dark as the lunar seas and there are significantly fewer of them than on the Moon. Such areas on Mercury are concentrated in the area of ​​the Zhary Plain (diameter 1300 km).

Pictures and Map of Mercury

Video

>> Rotation of Mercury

Peculiarities rotation of Mercury around the Sun: speed, period, how much time the planet spends in orbit in the solar system, length of the day and year with photo.

Of all the planets, motion and period rotation of Mercury is the most unusual. The fact is that the process of axial rotations itself occurs slowly. If the axis of rotation of Mercury takes 175.97 days, then it takes 88 days to fly around the Sun. That is, a day lasts 1.999 times more than a year. The equatorial speed indicator is 10.892 km/h. This results in sunny days, where 58.647 days are spent per revolution.

If you were to visit the planet, you could watch the Sun rise halfway and stay at one point throughout the day. This happens 4 days before the moment of perihelion due to the fact that the orbital speed exceeds the angular speed, and the star starts moving backwards.

Mercury's rotation around the Sun

Let's take a closer look at Mercury's rotation around the Sun. During one of the Mercury years, the average solar motion reaches two degrees per day in a westerly direction, causing the day to be three times longer than the rotation. Traffic will vary depending on the year. And at the moment of aphelion it will slow down and give 3 degrees per day. But the Sun will also slow down and stop its shift to the west, move to the east and return to the west again. The tilt of Mercury's rotation axis is demonstrated below.

It is worth understanding that at the moment the solar speed changes, the star will increase in its observed size and then decrease.

The peculiarities and speed of rotation of the planet were not known until 1965. Then it was believed that everything depended on the planetary tides to the Sun. The breakthrough was made by Soviet researchers who, in 1962, managed to bounce radio signals off the surface of Mercury. Later, the Americans used Arecibo and confirmed the results, as well as the rotation period, which reached 58.647 days.