To find out whether there are celestial bodies that glow themselves, you first need to understand which ones. celestial bodies consists of the solar system. The solar system is a planetary system in the center of which there is a star - the Sun, and around it there are 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. In order for a celestial body to be called a planet, it must meet these requirements
Make rotational movements around the star.
Have a spherical shape due to sufficient gravity.
Do not have other large bodies around its orbit.
Don't be a star.
Objects tend to form spheres. If they are massive enough, they will overcome the forces preventing this. Today we still look at stars, planets and their moons as spherical bodies. But smaller celestial bodies, such as asteroids and comets, are often irregularly shaped and tend to look more like potatoes.
The shape of a body is determined by the interaction of its gravity and strength. Small asteroids and comets have little gravity, which is not enough to force their larger rocks into a spherical distribution. But the gravity of much larger moons and planets is so strong that it turns these celestial bodies into spheres. Of course, there are still irregular features on the surface of planets, such as mountains and valleys, but they become smaller as gravity increases.
Planets do not emit light; they can only reflect the rays of the Sun that fall on them. Therefore, it cannot be said that planets are celestial bodies that glow themselves. Such celestial bodies include stars. The sun is the source of light on Earth. Celestial bodies that glow themselves are stars. The closest star to Earth is the Sun. Thanks to its light and warmth, all living things can exist and develop. The Sun is the center around which the planets, their satellites, asteroids, comets, meteorites and cosmic dust revolve.
Regardless of the material composition of the celestial body, a diameter of several hundred miles is sufficient to create a spherical shape - the largest asteroids, Ceres and Vesta, already have a pronounced round shape. The shape of celestial bodies is not ideal. Rotation - that is, rotation around its own axis - also plays an important role in relation to the shape of celestial bodies. For example, the asteroid Cleopatra completes its rotation in just 3 hours and therefore has an elongated dumbbell shape: it is 135 miles long with a diameter of only about 56 miles.
Large planets are also deformed through their rotation. The faster a planet rotates, the wider it becomes at the equator and flatter at the poles. Our Earth is also not an ideal sphere. Its diameter above the poles is 5 miles less than at the equator. Modern exploration of the Universe confirms that there is great energy in matter, its components and celestial bodies. Allah can destroy it and recreate it. Scientists have discovered various shapes powerful energy that flows in heaven and on earth.
The sun appears to be a solid spherical object because when you look at it, its outline appears quite clear. However, it does not have a solid structure and consists of gases, the main one of which is hydrogen; other elements are also present.
To see that the Sun does not have clear contours, you need to look at it during an eclipse. Then you can notice that it is surrounded by a moving atmosphere, which is several times larger than its diameter. During normal aurora, this halo is not visible due to the bright light. Thus, the Sun does not have precise boundaries and is in a gaseous state. Stars The number of existing stars is unknown; they are located at a great distance from the Earth and are visible as small dots. Stars are celestial bodies that glow themselves. What does this mean? Stars are hot balls of gas in which thermonuclear reactions occur. Their surfaces have different temperatures and densities. Stars also differ in size, being larger and more massive than planets. There are stars whose sizes exceed the size of the Sun, and there are also vice versa.
Strong Nuclear Energy: This energy combines subatomic particles; which includes protons, electrons and neutrons. Weak Nucleon Energy: This nuclear energy causes certain forms of radioactive decay. It is the energy that binds the atoms within matter and which also gives each its corresponding characteristics. Gravity: This is the weakest form of energy known to us, but is ultimately the focal form of energy as it holds all celestial bodies in their respective positions. Electromagnetic energy. . In these verses, Allah states that the sun moves in a certain direction.
A star consists of gas, mostly hydrogen. On its surface, due to high temperature, the hydrogen molecule breaks down into two atoms. An atom consists of a proton and an electron. However, under the influence of high temperatures, atoms “release” their electrons, resulting in a gas called plasma. An atom left without an electron is called a nucleus. How stars emit light A star, due to gravitational force, tries to compress itself, as a result of which the temperature in its central part rises greatly. Nuclear reactions begin to occur, resulting in the formation of helium with a new nucleus, which consists of two protons and two neutrons. As a result of the formation of a new nucleus, a large number of energy. Particles-photons are released as excess energy - they also carry light. This light exerts a strong pressure that emanates from the center of the star, resulting in a balance between the pressure emanating from the center and the gravitational force
Previously, it was believed that the sun was motionless. Modern cosmologists and astronomers have confirmed that the sun moves in a certain direction. All the planets in this solar system moving like satellites. The Earth's orbit is concentric to the orbits of the planets. On Arabic the word "Hubuk" has more than one meaning.
Perfection in creation: Astronomers estimate that there are two hundred billion galaxies and about seventy billion trillion stars in the universe. 19 Each galaxy varies in its size, shape, density, the speed at which it moves on its axis, its distance from us, and the distance of each from the other, the stages it has passed through, the number of stars and the life of each of their stars. These astonishing numbers regarding the number of galaxies and stars in the known universe represent only 10% of the entire universe. There must be a force that holds it all together, otherwise it will collapse and fall into chaos.
- It also refers to a piece that fits and integrates perfectly.
- Far removed is Allah from every imperfection, Who said.
Thus, celestial bodies that glow themselves, namely stars, glow due to the release of energy during nuclear reactions. This energy is used to restrain gravitational forces and emit light. The more massive the star, the more energy is released and the brighter the star shines. Comets A comet consists of an ice clot containing gases and dust. Its core does not emit light, but when approaching the Sun, the core begins to melt and particles of dust, dirt, and gases are released into outer space. They form a kind of foggy cloud around the comet, which is called a coma.
This proves that this universe operates in a perfect system. The perfect difference between the light given off by a luminous, fiery body and the light reflected from the sun by a dark, cold body, which is then reflected in a constant and stable manner, was mentioned in the Qur'an over fourteen centuries ago! This proves that the Quran is a Divine Revelation from Allah.
Throughout ancient world people showed an indelible fascination with the movements of celestial bodies. Other early sky watchers, including the Chinese, Babylonians, and Mayans, recorded precise observations of the five visible planets Mercury, Venus, Mars, Jupiter, and Saturn. Consideration of these questions raises two important issues. Why were prehistoric people so intent on observing the periodic movements of celestial bodies? And why are astronomical observation devices found on many sacred places peace?
It cannot be said that a comet is a celestial body that itself glows. The main light it emits is reflected sunlight. Being far from the Sun, the light of the comet is not visible and only when it approaches and receives the sun's rays does it become visible. The comet itself emits a small amount of light, due to the atoms and molecules of the coma, which release the quanta they receive sunlight. The “tail” of a comet is “scattering dust” that is illuminated by the Sun. Meteorites Under the influence of gravity, solid cosmic bodies called meteorites can fall onto the surface of the planet. They do not burn up in the atmosphere, but when passing through it they become very hot and begin to radiate bright light. Such a luminous meteorite is called a meteor. Under the pressure of air, a meteor can break into many small pieces. Although it gets very hot, the inside usually remains cold, because for so long a short time, which it falls, does not have time to heat up completely. We can conclude that celestial bodies that glow themselves are stars. Only they are capable of emitting light due to their structure and the processes occurring inside them. Conventionally, we can say that a meteorite is a celestial body that itself glows, but this becomes possible only when it enters the atmosphere.
Archaeoastronomers, those scientists who study ancient astronomy, have offered several answers to these questions. One explanation is that ancient people, deeply puzzled by the nature of existence, sought to find meaning in the orderly movement of the heavens. By observing the celestial bodies and integrating human activity with their reliable cyclical movements, humans were able to live in harmony with the supernatural influences that permeated the universe. The night sky was a grand textbook from which early humans acquired a deep sense of cyclical time, the order and symmetry and predictability of nature.
Federal Agency for Education State Educational Institution of Higher Professional Education Ural State Mining University.
Faculty of ISP.
- Types of space objects
- Examination on the discipline
- Concepts of Modern Natural Science
- Student: Malakhov Ya.I. Group:
CEMT-11-1
- Teacher: Adrianovsky B.P.
- Ekaterinburg - 2011
Maintaining
Space object - a celestial body (astronomical object) or spacecraft located outside the earth's atmosphere in outer space.Natural space objects include stars, planets and their natural satellites, asteroids, comets, etc. Artificial space objects - spacecraft, the last stages of launch vehicles and their parts.
Classification of the names of celestial bodies of the Solar System
Another explanation for why the ancients observed the heavens has been suggested by mythology. In some long-forgotten era, the significant idea arose that the celestial bodies represented gods and goddesses with the power to guide, influence, or interfere with human life. By the time astronomical observations were carried out in ancient Mesopotamia and Egypt, a pantheon of heavenly gods and goddesses was firmly established, with each god or goddess having authority over a specific area of human experience.
In this work we will try to consider all the species diversity of astronomical objects presented in our Universe.
General characteristics of astronomical objects.
A celestial body (or more precisely an astronomical object) is material object, naturally formed in outer space. Celestial bodies include comets, planets, meteorites, asteroids, stars, etc. Astronomy studies celestial bodies.
The sizes of celestial bodies vary - from huge to tiny. The largest are, as a rule, stars, the smallest are meteorites. Celestial bodies are combined into systems depending on what these bodies are.
Studying the names of celestial bodies of the solar system
Observing the movements of the heavens was to understand the behavior of gods and goddesses. Both explanations seem reasonable. Other answers offered by archaeoastronomers are nothing more than unsubstantiated hypotheses. One example of such erroneous assumptions is the idea that astronomical observations were used by early humans primarily to prepare an agricultural calendar. It is believed that such a calendar will determine the exact days in the year when the seeds will be planted and when the harvest should be harvested.
Stars
Star? - a celestial body in which thermonuclear reactions are occurring, have occurred, or will occur. But most often a star is a celestial body in which thermonuclear reactions are currently taking place. The Sun is a typical star of spectral class G. The stars are massive luminous gaseous (plasma) balls. They are formed from a gas-dust environment (mainly hydrogen and helium) as a result of gravitational compression. The temperature of matter in the interior of stars is measured in millions of kelvins, and on their surface - in thousands of kelvins. The energy of the vast majority of stars is released as a result of thermonuclear reactions converting hydrogen into helium, occurring at high temperatures in the internal regions. Stars are often called the main bodies of the Universe, since they contain the bulk of luminous matter in nature. It is also noteworthy that stars have negative heat capacity.With the naked eye (with good visual acuity), about 6,000 stars are visible in the sky, 3,000 in each hemisphere. All stars visible from Earth (including those visible through the most powerful telescopes) are located in the local group of galaxies.
Oldest dead galaxy
But let's question this idea. Did ancient people really need sophisticated astronomical observations to tell them when to plant seeds? Could they not just take their cues from the native plants around them? Great amount evidence collected from both ancient folklore and modern research, indicates what people have always observed life cycles wild plants to determine when to prepare the soil and plant the seeds. People picked up these signals from wild plants in areas of the world where detailed astronomical observations had never been made.
Types of stars
Basic (Harvard) spectral classification of starsBrown dwarfs
Brown dwarfs are a type of star in which nuclear reactions could never compensate for the energy lost to radiation. For a long time, brown dwarfs were hypothetical objects. Their existence was predicted in the middle of the 20th century, based on ideas about the processes occurring during the formation of stars. However, in 2004, a brown dwarf was discovered for the first time. To date, quite a lot of stars of this type have been discovered. Their spectral class is M - T. In theory, another class is distinguished - designated Y.
In the regions where such observations were made, people were using local plant signals long before astronomical observing devices were ever installed. Moreover, although the structural landmarks of many prehistoric observatories indicate specific astronomical periods that coincide with the agricultural cycle, these periods are quite precise; they happen every year at the same time. However, seed planting is imprecise. This is not always done on the same day, but varies depending on different climatic conditions every year.
White dwarfs
Soon after the helium flash, carbon and oxygen “ignite”; each of these events causes a strong restructuring of the star and its rapid movement along the Hertzsprung-Russell diagram. The size of the star's atmosphere increases even more, and it begins to intensively lose gas in the form of scattering streams of stellar wind. The fate of the central part of the star depends entirely on its initial mass: the core of the star can end its evolution as a white dwarf (low-mass stars), if its mass in the later stages of evolution exceeds the Chandrasekhar limit - as a neutron star (pulsar), if the mass exceeds The Oppenheimer-Volkov limit is like a black hole. In the last two cases, the completion of the evolution of stars is accompanied by catastrophic events - supernova explosions.
The vast majority of stars, including the Sun, end their evolution by contracting until the pressure of degenerate electrons balances gravity. In this state, when the size of the star decreases by a hundred times, and the density becomes a million times higher than the density of water, the star is called a white dwarf. It is deprived of energy sources and, gradually cooling down, becomes dark and invisible.
A longer than normal winter followed by a later than normal spring will naturally influence wild plants to drop their seeds later than last year. People who take their cues from the plant world also delay their own planting to be in tune with seasonal cycles.
In addition, various cultivated plants are sown in different time year, from early spring until late summer, and prehistoric astronomical observatories certainly did not record all of these individual landing times. They also did not have to specify the harvest time. Nature, of course, does not need astronomical observatories to tell her when an apple is ripe; the apple just falls to the ground. Farmers also do not need astronomical observations to guide their harvest times. By being in the fields growing their crops every day, farmers would know when to harvest each specific bread and vegetable.
Red giants
Red giants and supergiants are stars with a fairly low effective temperature (3000 - 5000 K), but with enormous luminosity. The typical absolute magnitude of such objects is 3m-0m (luminosity class I and III). Their spectrum is characterized by the presence of molecular absorption bands, and the maximum emission occurs in the infrared range.
They learned this not from observing the sky above their heads, but directly from the plants they grew. Finally, and most importantly, many ancient astronomical observatories were used to establish numerous days of the solar year that have nothing to do with the agricultural calendar. For example, summer solstice occurs in the middle of the growing season, and the winter solstice occurs during the coldest part of winter, when the ground freezes and crops do not grow. These days were extremely important for ancient people.
Variable stars
A variable star is a star whose brightness has changed at least once in its entire observation history. There are many reasons for variability and they can be associated not only with internal processes: if the star is double and the line of sight lies or is at a slight angle to the field of view, then one star, passing through the disk of the star, will eclipse it, and the brightness may also change if the light from the star will pass through a strong gravitational field. However, in most cases, variability is associated with unstable internal processes. IN latest version The general catalog of variable stars adopts the following division:
Eruptive variable stars- these are stars that change their brightness due to violent processes and flares in their chromospheres and coronas. Changes in luminosity usually occur due to changes in the envelope or mass loss in the form of variable-intensity stellar wind and/or interaction with the interstellar medium.
Pulsating Variable Stars are stars that exhibit periodic expansion and contraction of their surface layers. Pulsations can be radial or non-radial. Radial pulsations of a star leave its shape spherical, while non-radial pulsations cause the star's shape to deviate from spherical, and neighboring zones of the star may be in opposite phases.
Rotating Variable Stars- these are stars whose brightness distribution over the surface is non-uniform and/or they have a non-ellipsoidal shape, as a result of which, when the stars rotate, the observer records their variability. Inhomogeneities in surface brightness can be caused by spots or temperature or chemical irregularities caused by magnetic fields whose axes are not aligned with the star's rotation axis.
Cataclysmic (explosive and nova-like) variable stars. The variability of these stars is caused by explosions, which are caused by explosive processes in their surface layers (novae) or deep in their depths (supernovae).
Eclipsing binary systems.
Optical variable binary systems with hard X-ray emission
New Variable Types- types of variability discovered during the publication of the catalog and therefore not included in already published classes.
Since they have nothing to do with the agricultural cycle, they lead us to ignore the existing archaeoastronomical theory that early farmers used prehistoric observatories as indicators of planting and harvest dates.
White dwarf - pulsar
Why then did ancient people care so much about accurately observing various celestial objects? And why did they orient so many of their sacred structures according to the movements of the sun, moon, planets and different stars? Let's consider some of the data from modern astronomy and geophysics about the influence of celestial bodies.
New
A nova is a type of cataclysmic variable. Their brightness does not change as sharply as that of supernovae (although the amplitude can be 9m): a few days before the maximum, the star is only 2m fainter. The number of such days determines which class of novae the star belongs to:
Very fast if this time (denoted as t2) is less than 10 days.
Fast - 11
Very slow: 151
Extremely slow, staying close to the maximum for years.
These fields greatly influence the electromagnetic fields of the Earth and all life on the planet. Decades of research in this area continue to demonstrate that metabolic processes in living organisms are oriented to astronomical periodicities, such as the rotation of the Earth on its axis, the revolution of the Earth around the Sun, and the Earth's surrounding moon. Indeed, it is now believed that there is no physiological process that does not exhibits cyclical changes and that all organisms on Earth contain metabolic clocks that cause significant internal biological actions at appropriate intervals related to geo-targeted cycles.
There is a dependence of the maximum brightness of the nova on t2. Sometimes this dependence is used to determine the distance to a star. The flare maximum behaves differently in different ranges: while in the visible range there is already a decline in radiation, in the ultraviolet it is still growing. If a flash is also observed in the infrared range, then the maximum will be reached only after the glare in the ultraviolet subsides. Thus, the bolometric luminosity during a flare remains unchanged for quite a long time.
In our Galaxy, two groups of novae can be distinguished: new disks (on average, they are brighter and faster), and new bulges, which are a little slower and, accordingly, a little weaker.
Supernovae
Supernovae are stars that end their evolution in a catastrophic explosive process. The term “supernovae” was used to describe stars that flared up much (by orders of magnitude) more powerfully than the so-called “novae.” In fact, neither one nor the other are physically new; existing stars always flare up. But in several historical cases, those stars flared up that were previously practically or completely invisible in the sky, which created the effect of the appearance of a new star. The type of supernova is determined by the presence of hydrogen lines in the flare spectrum. If it is there, then it is a type II supernova, if not, then it is a type I supernova.
Hypernovae
Hypernova - the collapse of an exceptionally heavy star after there are no more sources left in it to support thermonuclear reactions; in other words, it is a very large supernova. Since the early 1990s, stellar explosions have been observed so powerful that the force of the explosion exceeded the power of an ordinary supernova by about 100 times, and the energy of the explosion exceeded 1046 joules. In addition, many of these explosions were accompanied by very strong gamma-ray bursts. Intensive study of the sky has found several arguments in favor of the existence of hypernovae, but for now hypernovae are hypothetical objects. Today the term is used to describe the explosions of stars with masses ranging from 100 to 150 or more solar masses. Hypernovae could theoretically pose a serious threat to the Earth due to a strong radioactive flare, but at present there are no stars near the Earth that could pose such a danger. According to some data, 440 million years ago there was a hypernova explosion near the Earth. It is likely that the short-lived nickel isotope 56Ni fell to Earth as a result of this explosion.
Neutron stars
In stars more massive than the Sun, the pressure of degenerate electrons cannot contain the compression of the core, and it continues until most of the particles turn into neutrons, packed so tightly that the size of the star is measured in kilometers, and its density is 280 trillion. times the density of water. Such an object is called a neutron star; its equilibrium is maintained by the pressure of the degenerate neutron matter.
Composite objects.
Star systemsStellar systems can be single and multiple: double, triple and higher multiplicity. If a system includes more than ten stars, then it is usually called a star cluster. Double (multiple) stars are very common. According to some estimates, more than 70% of the stars in the galaxy are multiples. Thus, among the 32 stars closest to Earth, 12 are multiple, of which 10 are double, including the brightest visually observable star Sirius. In the vicinity of 20 parsecs from the Solar System there are more than 3000 stars, about half are double stars of all types.
Double stars
A double star, or binary system, is two gravitationally bound stars revolving in closed orbits around a common center of mass. With the help of double stars, it is possible to find out the masses of stars and construct various dependencies. And without knowing the relationship between mass - radius, mass - luminosity and mass - spectral class, it is practically impossible to say anything about the internal structure of stars or their evolution.
But binary stars would not be studied so seriously if all their significance was reduced to information about mass. Despite repeated attempts to search for single black holes, all black hole candidates are found in binary systems. Wolf-Rayet stars were studied precisely thanks to double stars.
Close binary stars (Close Binary System - TDS)
Among double stars, the so-called close binary systems (CLS) are distinguished: binary systems in which matter is exchanged between stars. The distance between the stars in a close binary system is comparable to the size of the stars themselves, so in such systems more complex effects arise than just attraction: tidal distortion of the shape, heating by the radiation of a brighter companion, and other effects.
Star clusters
A star cluster is a gravitationally bound group of stars that has a common origin and moves in the gravitational field of the galaxy as a single whole. Some star clusters also contain, in addition to stars, clouds of gas and/or dust.
According to their morphology, star clusters are historically divided into two types - globular and open. In June 2011, it became known about the discovery of a new class of clusters, which combines the characteristics of both globular and open clusters.
Groups of gravitationally unbound stars or weakly bound young stars united by a common origin are called stellar associations.
Ball
A globular star cluster is a star cluster that differs from an open cluster in a larger number of stars, a clearly defined symmetrical shape, close to spherical, and with an increase in the concentration of stars towards the center of the cluster. The spatial concentrations of stars in the central regions of globular clusters are? 103-104 pc? 3 (for comparison, in the vicinity of the Sun the spatial concentration of stars is? 0.13 pc? 3, that is, in the vicinity of the Sun the stellar density is 7-70 thousand times less) , number of stars? 104-106. The diameters of globular clusters are 20-60 pc, the masses are 104-106 solar.
Scattered
An open star cluster is a star cluster that, unlike a globular cluster, contains relatively few stars and often has an irregular shape. In our galaxy and similar galaxies, open clusters are collective members and are part of a flat subsystem.
The largest clusters (such as the Pleiades) have been known since ancient times. Others were known as fuzzy nebulae, and it was only with the invention of the telescope that they could be separated into their constituent stars.
Young open clusters associated with the spiral arms of the galaxy have a characteristic composition. Red and yellow giants are rarely found in them and there are absolutely no red and yellow supergiants. At the same time, white and blue giants, which themselves are rare types of stars, are much more common in open clusters. Also, in open clusters more often than in other places in the Galaxy, you can find even rarer stars - white and blue supergiants, that is, stars of extremely high luminosity and temperature, emitting hundreds of thousands and even millions of times more than our Sun.
Galaxies
A galaxy is a giant gravitationally bound system of stars and star clusters, interstellar gas and dust, and dark matter. All objects within galaxies participate in motion relative to a common center of mass.
Galaxies are extremely distant objects; the distance to the nearest ones is usually measured in megaparsecs, and to distant ones - in units of redshift z. It is precisely because of their distance that only three of them can be distinguished in the sky with the naked eye: the Andromeda nebula (visible in the northern hemisphere), the Large and Small Magellanic Clouds (visible in the southern hemisphere). It was not possible to resolve images of galaxies down to individual stars until the beginning of the 20th century. By the early 1990s, there were no more than 30 galaxies in which individual stars could be seen, and all of them were part of the Local Group. After the launch of the Hubble Space Telescope and the commissioning of 10-meter ground-based telescopes, the number of galaxies in which it was possible to distinguish individual stars increased sharply.
Galaxies are very diverse: among them one can distinguish spherical elliptical galaxies, disk spiral galaxies, barred galaxies, dwarf galaxies, irregular galaxies, etc. If we talk about numerical values, then, for example, their mass varies from 107 to 1012 solar masses; for comparison, the mass of our Milky Way galaxy is 3?1012 solar masses. The diameter of galaxies is from 5 to 50 kiloparsecs (16-160 thousand light years), for comparison, the diameter of our Milky Way galaxy is about 100,000 light years.
Planets
A planet is a celestial body orbiting a star or its remnants, massive enough to become rounded under the influence of its own gravity, but not massive enough to initiate a thermonuclear reaction, and has managed to clear the vicinity of its orbit of planetesimals.
Planets can be divided into two main classes: large, low-density giant planets, and smaller Earth-like planets with a solid surface. According to the definition of the International Astronomical Union, there are 8 planets in the solar system. In order of distance from the Sun there are four earth-like ones: Mercury, Venus, Earth, Mars, then four giant planets: Jupiter, Saturn, Uranus and Neptune. There are also at least 5 dwarf planets in the Solar System: Pluto (considered the ninth planet until 2006), Makemake, Haumea, Eris and Ceres. With the exception of Mercury and Venus, all planets orbit at least one satellite.
Composition of planetary systems
An exoplanet or extrasolar planet is a planet orbiting a star outside the solar system. The planets are extremely small and dim compared to the stars, and the stars themselves are far from the Sun (the nearest is 4.22 light years away). Therefore, for a long time the problem of discovering planets near other stars was insoluble; the first exoplanets were discovered in the late 1980s. Now such planets have begun to be discovered thanks to improved scientific methods, often at the limits of their capabilities.
By the end of December 2011, the existence of 716 exoplanets was confirmed in 584 planetary systems, of which 86 had more than one planet. It should be noted that the number of reliable exoplanet candidates is much larger. Thus, the Kepler project has discovered more than 1,200 exoplanets with a reliability of about 99%, however, to obtain confirmed status, such planets must be re-registered using ground-based telescopes.
Planetary mass objects
A planetary mass object, PMA, or Planemo is a celestial body whose mass allows it to fall within the range of the definition of a planet, that is, its mass is greater than that of small bodies, but is not sufficient to initiate a thermonuclear reaction in the manner of a brown dwarf or star. By definition, all planets are planetary mass objects, but the purpose of the term is to describe celestial bodies that do not conform to what is typically expected of a planet. For example, free-floating planets that do not orbit stars, which may be "orphan planets" that have left their system, or objects that appeared during the collapse of a gas cloud - instead of the typical accretion from a protoplanetary disk for most planets (these are usually called subbrown dwarfs).
Orphan Planet
Some computer models of the formation of stars and planetary systems suggest that certain "planetary mass objects" may leave their system and go into interstellar space. Some scientists have argued that such objects have already been found roaming freely in space and should be classified as planets, although others have suggested that they could be low-mass stars.
Satellite planets and belt planets
Some large satellites are similar in size to the planet Mercury or even larger than it. For example, the Galilean moons and Titan. Alan Stern argues that location should not matter to a planet, and only geophysical features should be taken into account when awarding planetary status to an object. He proposes the term satellite planet for a planet-sized object orbiting another planet. Likewise, planet-sized objects in the Asteroid Belt or Kuiper Belt can also be considered planets according to Stern.
Comets
A comet is a small celestial body with a nebulous appearance, usually revolving around the Sun in elongated orbits. As the comet approaches the Sun, it forms a coma and sometimes a tail of gas and dust.Presumably, long-period comets come to us from the Oort Cloud, which contains a huge number of cometary nuclei. Bodies located on the outskirts of the Solar system, as a rule, consist of volatile substances (water, methane and other ices) that evaporate when approaching the Sun.
To date, more than 400 short-period comets have been discovered. Of these, about 200 were observed during more than one perihelion passage. Many of them belong to so-called families. For example, most of the shortest-period comets (their complete revolution around the Sun lasts 3-10 years) form the Jupiter family. Slightly smaller in number are the families of Saturn, Uranus and Neptune (the latter, in particular, includes the famous Comet Halley).
Comets arriving from deep space look like nebulous objects with a tail trailing behind them, sometimes reaching a length of several million kilometers. The comet's nucleus is a body of solid particles and ice shrouded in a hazy shell called a coma. A core with a diameter of several kilometers can have around it a coma 80 thousand km in diameter. Streams of sunlight dislodge gas particles from the coma and throw them back, pulling them into a long smoky tail that moves behind it in space.
The brightness of comets depends very much on their distance from the Sun. Of all the comets, only a very small part comes close enough to the Sun and Earth to be seen with the naked eye. The most prominent ones are sometimes called "great comets."
Asteroids
An asteroid is a relatively small celestial body in the Solar System moving in orbit around the Sun. Asteroids are significantly smaller in mass and size than planets, have an irregular shape, and do not have an atmosphere, although they may also have satellites.Asteroid classification
The general classification of asteroids is based on the characteristics of their orbits and a description of the visible spectrum of sunlight reflected by their surface.Orbit groups and families
Asteroids are grouped into groups and families based on the characteristics of their orbits. Usually the group is named after the first asteroid that was discovered in a given orbit. Groups are relatively loose formations, while families are denser, formed in the past during the destruction of large asteroids from collisions with other objects.
Spectral classes
In 1975, Clark R. Chapman, David Morrison, and Ben Zellner developed a system for classifying asteroids based on chromaticity, albedo, and characteristics of the spectrum of reflected sunlight. Initially, this classification defined only three types of asteroids:
Class C - carbon, 75% of known asteroids.
Class S - silicate, 17% of known asteroids.
Class M - metal, most others.
This list was later expanded and the number of types continues to grow as more asteroids are studied in detail:
Class A is a relatively rare class of asteroids in the inner part of the asteroid belt (only 17 asteroids of this type have been discovered since 2005).
Class B is a relatively rare class of asteroids belonging to the group of carbon asteroids. Among the asteroid population, class B objects predominate mainly in the outer part of the main asteroid belt, and are also dominated by inclination asteroids, in particular the Pallas family, which includes the second largest asteroid Pallas. They contain the original building material from which our solar system was formed.
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