Planet Mercury: interesting facts about the former satellite. Planets and their satellites

07.08.2020

Natural satellites are relatively small cosmic bodies that revolve around larger "host" planets. In part, a whole science is devoted to them - planetology.

In the 70s, astronomers assumed that Mercury had several celestial bodies dependent on it, as they caught ultraviolet radiation around it. Later it turned out that the light belonged to a distant star.

Modern equipment makes it possible to study the planet closest to the Sun in more detail. Today, all planetary scientists unanimously repeat that it has no satellites.

Moons of the planet Venus

Venus is called similar to the Earth, since they have the same compositions. But if we talk about natural space objects, then the planet named after the goddess of love is close to Mercury. These two planets of the solar system are unique in that they are completely alone.

Astrologers believe that Venus could have previously observed such, but to date, not a single one has been found.

How many natural satellites does the earth have?

Our native Earth has many satellites, but only one natural one, which every person knows from infancy, is the Moon.

The size of the Moon exceeds a quarter of the diameter of the Earth and is 3475 km. It is the only celestial body with such large dimensions relative to the "owner".

Surprisingly, its mass is small at the same time - 7.35 × 10²²² kg, which indicates a low density. Multiple craters on the surface are visible from Earth even without any special devices.

What are the moons of Mars?

Mars is a rather small planet, which is sometimes called red because of its scarlet hue. It is given by iron oxide, which is part of it. Today, Mars boasts two natural celestial objects.

Both moons, Deimos and Phobos, were discovered by Asaph Hall in 1877. They are the smallest and darkest objects in our comic system.

Deimos is translated as the ancient Greek god, sowing panic and horror. Based on observations, it is gradually moving away from Mars. Phobos, named after the god who brings fear and chaos, is the only satellite that is so close to the "owner" (at a distance of 6000 km).

The surfaces of Phobos and Deimos are abundantly covered with craters, dust and various loose rocks.

Moons of Jupiter

To date, the giant Jupiter has 67 satellites - more than any other planet. The largest of them are considered the achievement of Galileo Galilei, since they were discovered by him in 1610.

Among the celestial bodies orbiting Jupiter, it is worth noting:

Adrastea, with a diameter of 250 × 147 × 129 km and a mass of ~3.7 × 1016 kg;
Metis - dimensions 60 × 40 × 35 km, weight ~ 2 1015 kg;
Thebe, which has a scale of 116×99×85 and a mass of ~4.4×1017 kg;
Amalteyu - 250 × 148 × 127 km, 2 1018 kg;
Io with a weight of 9 1022 kg at 3660×3639×3630 km;
Ganymede, which, with a mass of 1.5 1023 kg, had a diameter of 5263 km;
Europe, occupying 3120 km and weighing 5 1022 kg;
Callisto, with a diameter of 4820 km having a mass of 1 1023 kg.

The first satellites were discovered in 1610, some from the 70s to the 90s, then in 2000, 2002, 2003. The last of them were discovered in 2012.

Saturn and its moons

Found 62 satellites, of which 53 have names. Most of them are composed of ice and rock, with a reflective feature.

The largest space objects of Saturn:

How many moons does Uranus have?

At the moment, Uranus has 27 natural celestial bodies. They are named after characters from famous works written by Alexander Pope and William Shakespeare.

Names and list by quantity with description:

Moons of Neptune

The planet, whose name is consonant with the name of the great god of the seas, was discovered in 1846. She was the first to be found through mathematical calculations, and not through observation. Gradually, new satellites were discovered in her, until 14 were counted.

List

Neptune's moons are named after nymphs and various sea deities from Greek mythology.

The beautiful Nereid was discovered in 1949 by Gerard Kuiper. Proteus is a non-spherical cosmic body and is studied in detail by planetary scientists.

Giant Triton is the iciest object in the solar system with a temperature of -240°C, and also the only satellite that rotates around itself in the opposite direction to the rotation of the "master".

Almost all satellites of Neptune have craters on the surface, volcanoes - both fiery and ice. They spew mixtures of methane, dust, liquid nitrogen and other substances from their depths. Therefore, a person will not be able to be on them without special protection.

What are the "satellites of the planets" and how many of them are there in the solar system?

Satellites are cosmic bodies that are smaller in size than the "host" planets and orbit the latter. The question of the origin of satellites is still open and is one of the key questions in modern planetary science.

To date, 179 natural space objects are known, which are distributed as follows:

Venus and Mercury - 0;
Earth - 1;
Mars - 2;
Pluto - 5;
Neptune - 14;
Uranus - 27;
Saturn - 63;
Jupiter - 67.

Technologies are improving every year, finding more celestial bodies. It is possible that new satellites will be discovered soon. We can only wait, constantly checking the news.

The largest satellite in the solar system

The largest moon in our solar system is Ganymede, a moon of the giant Jupiter. Its diameter, according to scientists, is 5263 km. The next largest is Titan with a size of 5150 km - the "moon" of Saturn. Closes the top three Callisto - Ganymede's "neighbor", with whom they share one "owner". Its scale is 4800 km.

Why do planets need satellites?

Planetologists at all times asked themselves the question "Why do we need satellites?" or “What effect do they have on the planets?” Based on observations and calculations, some conclusions can be drawn.

Natural satellites play an important role for the hosts. They create a certain climate on the planet. No less important is the fact that they serve as protection against asteroids, comets, and other dangerous celestial bodies.

Despite such a significant impact, satellites are still not mandatory for the planet. Even without their presence, life can be formed and maintained on it. This conclusion was made by American scientist Jack Lissauer from the NASA Science Space Center.

Mercury satellite
- a hypothetical celestial body of natural origin, revolving around Mercury. The existence of such a satellite was assumed for a short period of time, however, it is currently believed that Mercury has no natural satellites. On March 18, 2011, the MESSENGER spacecraft became the first artificial satellite of Mercury.

1 Finding a suspected satellite
2 Double star
3 See also
4 Notes

Finding a suspected satellite

On March 27, 1974, two days before the Mariner 10 automatic interplanetary station flew by Mercury, the instruments on board registered strong ultraviolet radiation in the vicinity of Mercury, the appearance of which turned out to be unexpected. According to Mariner mission science team member Michael McElroy, the radiation simply "had no right to be there" because the craft was facing the dark side of the planet. The next day, the radiation disappeared, but after the flight near Mercury on March 29, 1974 took place, it was registered again. The radiation had a wavelength less than 1000 Å. The radiation seemed to come from an object that had separated from Mercury. The opinions of astronomers were divided: some considered the object a star, others, pointing to two different directions from which the radiation was observed, said that a satellite had been detected. In addition, it was believed at the time that ultraviolet radiation must be trapped by the interstellar medium. Also, the calculated speed of the object (4 kilometers per second) corresponded to the expected speed of the satellite.

double star

31 Chalices - Possibly an eclipsing binary

Soon, however, it was discovered that the "satellite" was moving away from Mercury. Finally, the second discovered source of radiation was identified as the star 31 of the constellation of the Cup, which is a spectroscopic binary with a period of 2.9 days, which can be associated with radiation in the ultraviolet range. The source of radiation recorded on March 27, 1974 has not yet been discovered.

Although the satellite of Mercury was not discovered, this case led to an important discovery: as it turned out, the limiting (extreme) ultraviolet radiation is not completely absorbed by the interstellar medium, as a result of which observations in this range began to be actively carried out.

Notes

1 2 3 4 5 6 Schlyter P. Mercury's Moon, 1974 (English). Nine Planets: Appendix 7: Hypothetical Planets. Retrieved September 10, 2011. Archived from the original on January 23, 2012. (Russian translation)
1 2 Mercury "s moon that wasn't (English) // New Scientist. - 1974. - Vol. 63, fast. 913. - P. 602.
1 2 Stratford, R.L. (1980). "31 Crateris reexamined". The Observatory 100 . Bibcode: 1980Obs...100..168S. (HD 104337 near 11 58 17.515 −19 22 50.18)

Satellites of the terrestrial planets

Moons of Mars

The solar system formed about 4.6 billion years ago. A group of planets, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, together with the Sun make up the Solar System.

The sun

The sun - the central body of the solar system - is a star, a huge ball of gas, in the center of which nuclear reactions take place. The bulk of the mass of the solar system is concentrated in the Sun - 99.8%. That is why the Sun holds by gravity all the objects of the solar system, the size of which is not less than sixty billion kilometers Samygin S.I. Concepts of modern natural science - Rostov-on-Don, Phoenix, 2008.

Very close to the Sun, four small planets circulate, consisting mainly of rocks and metals - Mercury, Venus, Earth and Mars. These planets are called terrestrial planets.

Between the terrestrial planets and the giant planets is the asteroid belt Sagan K.E. Space - M., 2000 .. A little further there are four large planets, consisting mainly of hydrogen and helium. The giant planets do not have a solid surface, but they have an exceptionally powerful atmosphere. Jupiter is the largest of them. Followed by Saturn, Uranus and Neptune. All giant planets have a large number of satellites, as well as rings.

The most recent planet in the solar system is Pluto, which in its physical properties is closer to the satellites of the giant planets. Beyond the orbit of Pluto, the so-called Kuiper belt, the second asteroid belt, has been discovered.

Mercury, the closest planet to the Sun in the solar system, has been a complete mystery to astronomers for a long time. The period of its rotation around the axis was not accurately measured. Due to the lack of satellites, the mass was not known exactly. Proximity to the Sun prevented observations of the surface.

Mercury

Mercury is one of the brightest objects in the sky. In brightness, it is second only to the Sun, Moon, Venus, Mars, Jupiter and the star Sirius. In accordance with Kepler's 3rd law, it has the shortest period of revolution around the Sun (88 Earth days). And the highest average orbital speed (48 km / s) Hoffman V.R. Concepts of modern natural science - M., 2003 ..

The mass of Mercury is equal to the mass of the Earth. The only planet with less mass is Pluto. In terms of diameter (4880 km, less than half of the earth), Mercury also stands in the penultimate place. But its density (5.5 g/cm3) is approximately equal to the density of the Earth. However, being much smaller than the Earth, Mercury experienced a slight compression under the action of internal forces. Thus, according to calculations, the density of the planet before compression is 5.3 g/cm3 (for the Earth, this value is 4.5 g/cm3). Such a large uncompressed density, surpassing the density of any other planet or satellite, indicates that the internal structure of the planet is different from the structure of the Earth or the Moon Isaac A. Earth and space. From reality to hypothesis - M., 1999 ..

The large value of the uncompressed density of Mercury must be due to the presence of a large amount of metals. According to the most plausible theory, in the bowels of the planet there should be a core consisting of iron and nickel, the mass of which should be approximately 60% of the total mass. And the rest of the planet should consist mainly of silicates. The core diameter is 3500 km. Thus, it lies at a distance of about 700 km from the surface. Simplistically, you can imagine Mercury as a metal ball the size of the Moon, covered with a rocky 700 km crust.

One of the unexpected discoveries made by the American space mission "Mariner 10" was the detection of a magnetic field. Although it is approximately 1% of the Earth, it is just as significant for the planet. This discovery was unexpected due to the fact that it was previously believed that the inner part of the planet has a solid state, and, therefore, a magnetic field could not form. It is difficult to understand how such a small planet could store enough heat to keep the core in a liquid state. The most probable assumption is that the core of the planet contains a significant part of iron and sulfur compounds, which slow down the cooling of the planet and due to this, at least the iron-gray part of the core is in a liquid state Sagan K.E. Space - M., 2000 ..

The first data characterizing the planet from a close distance were obtained in March 1974 thanks to a spacecraft launched as part of the American space mission Mariner 10, which approached at a distance of 9500 km and photographed the surface at a resolution of 150 m.

Although the surface temperature of Mercury has already been determined on Earth, more accurate data have been obtained from close measurements. The temperature on the day side of the surface reaches 700 K, approximately the melting point of lead. However, after sunset, the temperature quickly drops to about 150 K, after which it cools more slowly to 100 K. Thus, the temperature difference on Mercury is about 600K, which is greater than on any other planet Sadokhin A.P. Concepts of modern natural science - M., Unity, 2006 ..

Mercury strongly resembles the Moon in appearance. It is covered with thousands of craters, the largest of which reach 1300 km in diameter. Also on the surface there are steep slopes that can exceed a kilometer in height and hundreds of kilometers in length, ridges and valleys. Some of the largest craters have rays like the craters Tycho and Copernicus on the Moon, and many of them have central peaks. Gorkov VL, Avdeev Yu.F. Space alphabet. Book about space - M., 1984 ..

Most of the relief objects on the surface of the planet were named after famous artists, composers and representatives of other professions who contributed to the development of culture. The largest craters are named Bach, Shakespeare, Tolstoy, Mozart, Goethe.

In 1992, astronomers discovered regions with high levels of radio wave reflection, similar in properties to those of reflection near the poles on Earth and Mars. It turned out that these areas contain ice in craters covered with shadow. And while the existence of such low temperatures was not unexpected, the mystery turned out to be the origin of this ice on a planet, the rest of which is exposed to high temperatures and is completely dry.

Distinctive features of Mercury - long escarpments, which sometimes cross craters, are evidence of compression. Obviously, the planet was shrinking, and cracks were going along the surface. And this process took place after most of the craters formed. If the standard crater chronology is correct for Mercury, then this shrinkage must have occurred during the first 500 million years of Mercury's history.

Flickering in front of us mainly on the pages of atlases, monitors and TV screens, arouse keen interest. A lot of data has been collected about our solar system over the past century, when the development of space technology has made a leap forward. However, people who are far from astronautics and astronomy have not such wide knowledge about the planets that are neighbors to the Sun.

We are going to talk about one of the small planets of the solar system in this article. This is the closest to the Sun, one of the smallest. What do you think, what secret is fraught with this celestial body? To solve it, you must first remember whether there are satellites of Mercury. Difficult, right? And now let's go on a journey into entertaining astronomical facts.

What do we already know about Mercury?

The school curriculum provides not too extensive knowledge about the planets of the solar system, but sufficient for the sector of general knowledge.

Mercury is one of the solar system (after Pluto was expelled from the planetary system, it is the smallest). It is also closest to the Sun.

The planet has a small mass relative to our Earth (only 1/20). At the same time, most of the body of the object is a liquid core, which, according to some researchers, contains a high level of iron.

In addition, we also know how many satellites Mercury has: it does not have them. However, not everything turned out to be so unambiguous in the world of astronomers.

Mysterious celestial body: the history of the hypothesis

As we have already said, the existence of a natural satellite was not a scientific hypothesis for long. It is interesting on the basis of what conclusions it was put forward at the time.

So, it happened in 1974, on March 27th. At this time, the interplanetary station "Mariner-10" was approaching Mercury. Instruments on board the station recorded ultraviolet radiation, which a priori should not have been on this section of the path. At least the astronauts thought so.

The next day there was no radiation. Two days later, on March 29, the station again flew near Mercury and again recorded ultraviolet radiation. According to its characteristics, it could come from a separated from the planet.

Versions of scientists about objects near Mercury

Under the current conditions, the research team has new data for versions of whether Mercury has satellites. Regarding this alleged object, scientists have several versions. Some were convinced that it was a star, others that it was a satellite. The last version was supported by some data related to the current assumptions about the existence of the interstellar medium at that time.

For a long time, studies of the outer space of Mercury were carried out in order to discover the source of ultraviolet radiation. However, neither then nor now there is no data on that object.

How many moons does Mercury have?

Thus, we can repeat the hypothesis of scientists and take into account the historical existence of a certain satellite of Mercury. At the moment, there is an unequivocal answer to the question of how many satellites Mercury has - not a single natural one.

There is no data on the number of space objects revolving around this planet. Only artificial space bodies launched by man now fit the definition of a satellite of a given celestial body.

So, the satellite of Mercury is a hypothetical space object revolving around the planet, was considered to be of natural origin. That is, its presence (at least hypothetical) would be the answer to the question of whether there are natural satellites of Mercury. This hypothesis existed for a short time, its adherents became less and less. Subsequently, the first artificial satellite of Mercury was launched. This happened in March 2011. The existence of natural satellites has not been confirmed.

Conclusion

This article will touch on an interesting aspect of astronomy that you most likely were not taught about in school. When describing the planets of the solar system, much attention is paid to natural and artificial satellites.

At the current stage of development of astronomical science, there are no doubts about the absence of natural satellites of Mercury. However, there was another period in science, when, after capturing ultraviolet radiation in an unusual part of outer space, scientists came up with various hypotheses. Among them were suggestions that the natural satellites of Mercury exist.

What other mysteries the cosmos will present in such a space as our solar system, we can only assume and rely on science fiction writers. Perhaps the satellites of Mercury and other cosmic bodies, which planetology is not aware of now, will still be discovered.

Of natural origin, revolving around Mercury. The existence of such a satellite was assumed for a short period of time, however, it is currently believed that Mercury has no natural satellites. On March 18, 2011, the MESSENGER spacecraft became the first artificial satellite of Mercury.

Finding a suspected satellite

On March 27, 1974, two days before the passage of the automatic interplanetary station Mariner-10 near Mercury, the instruments on board registered strong ultraviolet radiation in the vicinity of Mercury, the appearance of which turned out to be unexpected. According to Mariner mission science team member Michael McElroy (English) Russian, the radiation simply “had no right to be there” (English “had no right to be there”), since the device was turned to the dark side of the planet. The next day, the radiation disappeared, but after the flight near Mercury on March 29, 1974 took place, it was registered again. The radiation had a wavelength less than 1000 . The radiation seemed to come from an object that had separated from Mercury. Opinions of astronomers were divided: some considered the object a star, others, pointing to two different directions from which the radiation was observed, said that a satellite had been detected. In addition, it was believed at the time that ultraviolet radiation must be trapped by the interstellar medium. Also, the calculated speed of the object (4 kilometers per second) corresponded to the expected speed of the satellite.

double star

Soon, however, it was discovered that the "satellite" was moving away from Mercury. In the end, the second discovered source of radiation was identified as the star 31 of the constellation Chalice, which is a spectroscopic binary with a period of 2.9 days, which can be associated with radiation in the ultraviolet range. The source of radiation recorded on March 27, 1974 has not yet been discovered