By small bodies of the Solar System we usually mean well-known asteroids and comets. For a long time it was believed that there were two main reservoirs of these small bodies in the Solar System. One of them is the Main Asteroid Belt, which is located between Mars and the other is the Oort Cloud, located far at the edge of the solar system. The main asteroid belt, as its name suggests, contains only asteroids. And the Oort Cloud is the main reservoir for comets. This cloud bears the name of the famous Dutch astronomer who predicted its existence.
Ancient witnesses
The traditional interest in the study of comets and asteroids is as follows. It is generally believed that these small bodies consist of material left over from the protoplanetary disk stage around the Sun. This means that their study provides information about the processes that took place in the Solar system even before the formation.
Asteroids are small planets with diameters ranging from 1 to 1000 km. Their orbits are located approximately between the orbits of Jupiter.
The history of the discovery of the Main Asteroid Belt began with a prediction in 1596 by the great astronomer Johannes Kepler. He believed that there must be a separate planet between the orbits of Mars and Jupiter. In 1772, the German scientist I. Titius proposed an empirical formula according to which an unknown planet should be at a distance of 2.8 AU. from the Sun (1 AU is one astronomical unit, equal to the distance from the Earth to ~150 million km). The law that is described by this formula is called the Titius-Bode law. In 1796, at a special congress of scientists and astronomers, a project to search for this unknown planet was adopted. And four years later, Italian astronomer G. Piazzi discovered the first asteroid - .
Then the famous German astronomer G. Olbers discovered a second asteroid, called Pallas. This is how the discovery of the Main Asteroid Belt of the Solar System took place. By the beginning of 1984, the number of asteroids in this belt with reliably established orbital parameters reached 3000. Scientific work on the discovery of new asteroids and the refinement of their orbits continues to this day.
Comets and the Oort cloud
Another type of small body - comets, also belongs to the Solar System. Comets typically move around the Sun in elongated elliptical orbits of varying sizes. They are arbitrarily oriented in space. The size of the orbits of most comets is thousands of times larger than the diameter of the planetary system. Most of the time, comets are at the most distant points of their orbits (aphelia). Thus forming a comet cloud on the distant outskirts of the solar system. This cloud is called the Oort Cloud.
This cloud extends far from the Sun, reaching distances of 105 AU. The Oort Cloud is believed to contain up to 1011 cometary nuclei. The orbital periods of the most distant comets around the Sun can reach values of 106-107 years. Let us recall that the famous comet of our days, Comet Hale-Bopp, arrived to us from the immediate vicinity of the Oort Cloud. Its orbital period is only (!) about three thousand years.
Formation of the Solar System
The problem of the origin of small bodies of the Solar System is closely related to the problem of the origin of the planets themselves. In 1796, the French scientist P. Laplace put forward a hypothesis about the formation of the Sun and the entire solar system from a contracting gas nebula. According to Laplace, part of the gaseous substance was separated from the core of the nebula under the influence of the centrifugal force that increased during compression. This directly follows from the law of conservation of angular momentum. This substance served as the material for the formation of planets.
This hypothesis encountered difficulties that were overcome in the works of American scientists F. Multon and T. Chamberlain. They showed that it was more likely that planets formed not directly from gas, but rather from small solid particles, which they called planetesimals. Therefore, it is currently believed that the process of formation of the planets of the solar system took place in two stages. At the first stage, many intermediate bodies hundreds of kilometers in size (planetosimals) were formed from the dust component of the primary cloud of circumsolar matter. And only then, at the second stage, planets accumulated from a swarm of intermediate bodies and their fragments.
There may be several reservoirs of such intermediate bodies, or planetesimals, in the Solar System. In 1949, astronomer K.E. Edgeworth, and then in 1951 by astronomer J.P. Kuiper (G.P. Kuiper) predicted the existence of another reservoir - a family of trans-Neptunian objects. They arose at an early stage in the formation of the Solar System. As remnants of a protoplanetary disk, these predicted objects would be concentrated in low-eccentricity and low-inclination orbits directly around Neptune. The hypothetical reservoir of such objects is called Kuiper belt (KP, Kuiper Belt).
DISCOVERY OF THE KUIPER BELT:
BASIC PROPERTIESOF ITS COMPONENT OBJECTS
Let's start with the fact that a study of the orbit of the famous Halley's comet allowed us to give a rough estimate of the mass of the Kuiper belt up to 50 AU. from the sun. It must be a fairly small fraction of the Earth's mass.
Numerous photographic searches for slow-moving Kuiper belt objects (KBOs) have not led to success for a long time. Finally, in 1930, astronomer Tomba discovered the first new object beyond the orbit of Neptune. It was the planet Pluto. It should immediately be noted that the mass of Pluto is unusually small and is only 0.0017 M of Earth. While the mass of Neptune is equal to 17.2 M of the Earth.
In 1979, a second object was discovered - 2060 Chiron, which belongs to a group of objects called Centaurs. A centaur is an object whose orbit lies in the region between Jupiter and Neptune. Failures in finding new objects were associated with the insufficient effectiveness of the photographic observation method. With the advent of solid-state semiconductor radiation detectors (called charge-coupled device CCDs), deeper surveys of the sky became possible. It has become possible to register light reflected from natural cosmic small bodies with a size of the order of 100 km or less in the region of the orbit of Neptune and beyond.
Astronomers have created a special program to search for such bodies - the Spacewatch program. And as a result of the work of this program, two more objects belonging to the Centaur group were discovered - these are 5145 Pholus and 1993NA2.
The Kuiper Belt is a disk-shaped region of icy objects beyond the orbit of Neptune - billions of kilometers from our Sun. Pluto and Eris are the most famous of these icy worlds. There could be hundreds more ice dwarfs out there. The Kuiper Belt and the even more distant Oort Cloud are believed to be home to comets orbiting the Sun.
10 Facts You Need to Know About the Kuiper Belt and Oort Cloud
1. The Kuiper Belt and Oort Cloud are regions of space. The known icy worlds and comets in both regions are significantly smaller than Earth's Moon.
2. The Kuiper Belt and Oort Cloud surround our Sun. The Kuiper Belt is a donut-shaped ring that expands just beyond the orbit of Neptune at a distance of approximately 30 to 55 AU. The Oort cloud is a spherical shell occupying space at a distance of five thousand to 100 thousand AU.
3. Long-period comets (those with orbital periods greater than 200 years) originate from the Oort Cloud. Short-period comets (orbital periods less than 200 years) originate in the Kuiper belt.
4. Within the Kuiper belt there may be hundreds of thousands of icy bodies larger than 100 km (62 miles) and about a trillion or more comets. The Oort cloud may contain more than a trillion icy bodies.
5. Some dwarf planets within the Kuiper Belt have thin atmospheres that collapse when their orbits take them to their furthest distance from the Sun.
6. Several dwarf planets in the Kuiper Belt have tiny moons.
7. There are no known rings around worlds in any part of space.
8. The first mission in the Kuiper belt is the New Horizons mission. It will reach Pluto in 2015.
9. As far as is known, a region of space is not capable of supporting life.
10 The Kuiper Belt and Oort Cloud are named after the astronomers who predicted their existence in the 1950s: Gerard Kuiper and Jan Oort.
Oort cloud
In 1950, Dutch astronomer Jan Oort proposed that some comets come from the vast, very distant spherical shell of icy bodies surrounding the solar system. This giant cloud of objects is now called the Oort Cloud, occupying a space between 5,000 and 100,000 astronomical units. (One astronomical unit, or AU, is equal to the average distance of the Earth from the Sun: about 150 million km or 93 million miles.)
The outer space of the Oort Cloud is believed to be in a region of space where the gravitational influence of the Sun is weaker than that of nearby stars.
Illustrated image of the Oort Cloud
The Oort cloud likely contains between 0.1 and 2 trillion icy bodies in solar orbit. Sometimes giant molecular clouds, passing stars, or tidal interactions with the disk of the Milky Way disturb the orbits of some of these bodies in the outer region of the Oort Cloud, causing objects to fall into the interior of the solar system, so-called long-period comets. These comets have very large, eccentric orbits and take thousands of years to circle the Sun. In human history, they have been observed in the inner Solar System only once.
Kuiper Belt
Unlike long-period comets, short-period comets take less than 200 years to orbit the Sun, and they travel in approximately the same plane as the orbits of most planets. They are thought to originate from a disk-shaped region beyond Neptune called the Kuiper Belt, named after astronomer Gerard Kuiper. (It is sometimes called the Edgeworth-Kuiper belt, acknowledging an independent and previous discussion by Kenneth Edgeworth.) Objects in the Oort cloud and Kuiper belt are thought to be remnants from the formation of the Solar System about 4.6 billion years ago.
Illustrated image of the Kuiper Belt
The Kuiper Belt extends from approximately 30 to 55 AU. and is likely filled with hundreds of thousands of icy bodies more than 100 km (62 mi) in diameter and an estimated trillion or more comets.
Kuiper Belt Objects
In 1992, astronomers discovered a faint speck of light from an object located around 42 AU. from the Sun—it was the first time a Kuiper Belt Object (or KBO for short) had been spotted. More than 1,300 OPCs have been identified since 1992. (Sometimes called Edgeworth-Kuiper objects, they are also called trans-Neptunian objects or TNOs for short.)
Largest trans-Neptunian objects
Because the OPCs are so far away, their size is difficult to measure. The calculated diameter of the OPC depends on the assumption of what the reflective surface of the object is. Using infrared observations from the Spitzer Space Telescope, the sizes of most of the largest OPCs have been determined.
One of the most unusual KBOs is the dwarf planet Haumea, which is part of an impact family orbiting the sun. This object, Haumea, apparently collided with another object that was about half its size. The impact caused large chunks of ice to explode and sent Haumeu spinning freely, causing him to spin up and down every four hours. It spins so fast that it takes the shape of a crushed American football. Haumea and two small moons, Hi'iaka and Namaka, make up the Haumea family.
In March 2004, a team of astronomers announced the discovery of a planet as a trans-Neptunian object orbiting the Sun at extreme distances, in one of the coldest known regions of our solar system. The object (2003VB12), named Sedna after the Eskimo goddess who lives at the bottom of the cold Arctic Ocean, approaches the Sun only briefly in its 10,500-year orbit. It never entered the Kuiper Belt, whose outer boundary region is located at approximately 55 AU. - Instead, Sedna moves on a long, elongated elliptical orbit from 76 to almost 1000 AU. from the sun. Because Sedna's orbit is at such an extreme distance, its discoverers suggested that it was the first celestial body observed to belong to the inner Oort Cloud.
In July 2005, a team of scientists announced the discovery of OPC, which was initially thought to be about 10 percent larger than Pluto. The object, temporarily designated 2003UB313 and later named Eris, orbits the Sun approximately once every 560 years, with a distance ranging from approximately 38 to 98 AU. (For comparison, Pluto moves from 29 to 49 AU in the solar orbit.) Eris has a small moon called Dysnomia. More recent measurements show it to be slightly smaller in size than Pluto.
The discovery of Eris—orbiting the Sun and similar in size to Pluto (which then came to be considered the ninth planet)—caused astronomers to consider whether Eris should be classified as the tenth planet. However, in 2006, the International Astronomical Union created a new class of objects called dwarf planets, and placed Pluto, Eris and the asteroid Ceres in this category.
Both distant regions are named after the astronomers who predicted their existence - Gerard Kuiper and Jan Oort. Objects discovered in the Kuiper Belt are named after characters from various mythologies. Eris is named after the Greek goddess of discord and enmity. Haumea is named after the Hawaiian goddess of fertility and childbirth. Comets from both areas are typically named after the person who discovered them.
Largest Kuiper Belt Objects
Dwarf planet Eris
The icy dwarf planet Eris takes 557 Earth years to complete one revolution around our Sun. The orbital plane of Eris is located outside the plane of the planets of the solar system and extends far beyond the Kuiper belt, into the zone of icy debris beyond the orbit of Neptune.
The dwarf planet Eris is so often far from the Sun that its atmosphere collapses and freezes completely on the surface in an icy glaze. Its surface reflects as much sunlight as freshly fallen snow.
Movement of Eris in the night sky
Scientists believe Eris's surface temperature ranges from -359 degrees Fahrenheit (-217 degrees Celsius) to -405 degrees Fahrenheit (-243 degrees Celsius). Eris's thin atmosphere begins to melt as the planet moves closer to the Sun, revealing its rocky, Pluto-like surface.
Eris turned out to be larger than Pluto. This discovery sparked debate in the scientific community and ultimately led to a revision of the planet's definition by the International Astronomical Union.
Eris may actually be smaller than Pluto, recent observations have shown. Pluto, Eris and other similar objects are currently classified as dwarf planets. They are also called plutoids, in recognition of Pluto's special place in our history.
Eris is too small and too distant to be seen. Dysnomia is the only known moon of the dwarf planet Eris. This and other small satellites around dwarf planets allowed astronomers to calculate the mass of the parent body.
Dysnomia plays an important role in determining how Pluto and Eris compare to each other.
All the asteroids in the asteroid belt could easily fit inside Eris. However, Eris, like Pluto, is smaller than the Earth's satellite the Moon.
Eris was first spotted in 2003 during a survey of the outer solar system by Mike Brown of Palomar Observatory, Chad Trujillo of Gemini Observatory, and David Rabinowitz of Yale University. The discovery was confirmed in January 2005 and was presented as a possible 10th planet in our solar system, as it was the first object in the Kuiper Belt to be larger than Pluto.
It was originally called 2003 UB313. Eris is named after the ancient Greek goddess of discord and enmity. The name is apt, as Eris remains at the center of scientific debate about the definition of a planet.
Eris's moon Dysnomia is named after the daughter of Eris, who was the goddess of lawlessness.
Dwarf planet Pluto
The dwarf planet Pluto is the only dwarf planet in the solar system that stood among the main planets. Not so long ago, Pluto was considered a full-fledged ninth planet, farthest from the Sun. It is now seen as one of the largest objects in the Kuiper Belt, a dark, disk-shaped zone beyond Newton's orbit containing trillions of comets. Pluto was classified as a dwarf planet in 2006. This event was seen as a demotion in status and caused heated debate and debate in scientific and public circles.
The history of the discovery of the planet Pluto
Signs of the existence of Pluto were first noticed by US astronomer Percival Lowell in 1905. While observing Neputnus and Uranus, he discovered deviations in their orbits and suggested that this was caused by the action of gravity of an unknown large celestial object. In 1915, he calculated the possible location of this object, but died without finding it. In 1930, Clyde Tombaugh of the Lowell Observatory, based on Lowell's predictions, discovered a ninth planet and announced its discovery.
Pluto is the only planet in the world whose name was given by an 11-year-old girl, Venice Burney (Oxford, England). Venice considered it appropriate to name the newly discovered planet after the Roman god and expressed this opinion to her grandfather. He passed on his granddaughter’s idea to the Lowell Observatory. The name Pluto was adopted. It should be noted that the first two letters of this word reflect the initials of Percival Lowell. Features of the planet Pluto
Because Pluto is so far from Earth, very little is known about its size and conditions on its surface. Pluto's mass is reportedly less than one-fifth that of Earth, and its diameter is about two-thirds that of the Moon. Pluto's surface is thought to consist of a rocky base covered by a mantle of water ice, frozen methane and nitrogen.
Strange mountains on Pluto that may be ice volcanoes
The orbit of the planet Pluto in the solar system has a large eccentricity, that is, it is very far from circular. Pluto's distance from the Sun can vary significantly. As Pluto approaches the Sun, its ice begins to melt and forms an atmosphere consisting primarily of nitrogen and methane. On Pluto, gravity is much lower than Earth's, so its atmosphere expands during a thaw, extending much higher than the Earth's atmosphere. It is assumed that when Pluto makes its return journey away from the Sun, most of its atmosphere freezes again, and almost completely disappears. While it has an atmosphere, Pluto's surface is likely to experience strong winds. Pluto's surface temperature is about -375 °F (-225 C).
Photo of Pluto's foggy Arctic taken by the New Horizons spacecraft
For a long time, due to the enormous distance to Pluto, astronomers knew little about its surface. But step by step they are getting closer to revealing many of its secrets. Thanks to the Hubble orbital telescope, images of Pluto were obtained. On them, different areas of the planet's surface appear in reddish, yellowish and grayish tones and with a curious bright spot near the equator. It is possible that this place is rich in frozen carbon monoxide. Compared to past Hubble photographs, Pluto's surface can be seen changing color over time, becoming redder. This is presumably due to seasonal changes.
Close-up view of the Tombaugh region on Pluto
Pluto's elliptical orbit is 49 times farther from the Sun than Earth's orbit. During its orbit around the Sun, which lasts 248 Earth years, Pluto is closer to the Sun for 20 years than Neptune. During this period, astronomers get the chance to study this small, cold, distant world. The last period of closest approach between Pluto and the Sun ended in 1999. Thus, after 20 years as the 8th planet, Pluto crossed the orbit of Neptune to once again become the most distant planet (before being classified as a dwarf).
Dwarf planet Makemake
Along with other dwarf planets such as Pluto and Haumea, Makemake is located in the Kuiper belt, a region located beyond the orbit of Neptune. Astronomers believe Makemake is only slightly smaller than Pluto. This dwarf planet takes about 310 Earth years to complete one revolution around our Sun.
Astronomers have discovered evidence of frozen nitrogen on the surface of Makemake. In addition, frozen ethane and methane were also detected. Astronomers believe that the methane granules present on Makemak may be up to one centimeter in diameter.
The scientists also found evidence of tholins, molecules that form whenever ultraviolet light from the sun interacts with substances such as ethane and methane. Tolins typically cause a reddish-brown color, which is why Makemake has a reddish tint to it when looking at it.
Makemake holds an important place in the solar system because it, along with Eris, was one of the objects whose discovery prompted the International Astronomical Union to redefine planets and create a new group of dwarf planets.
Makemake was first observed in March 2005 by Michael Brown, Chadwick Trujillo and David Rabinowitz at the Palomar Observatory. It was officially recognized as a dwarf planet by the International Astronomical Union in 2008.
It was originally designated 2005 FY9. Makemake is named after the god of fertility in Rapa Nui mythology. The Rapa Nui are the indigenous people of Easter Island in the southeastern Pacific Ocean, located 3,600 km off the coast of Chile.
Dwarf planet Haumea
The oddly shaped dwarf planet Haumea is one of the fastest-rotating large objects in our solar system. It rotates around its axis every four hours. Astronomers discovered the rapid rotation of the dwarf planet in 2003. It is about the same size as Pluto. Like Pluto and Eris, Haumea orbits our Sun in the Kuiper Belt, the far zone of icy objects beyond the orbit of Neptune. Hamuea takes 285 Earth years to complete a revolution around the Sun.
Perhaps billions of years ago, a large object crashed into Haumea and gave it this rotation, and at the same time created its two satellites: Hi'iaka and Namaka. Astronomers believe Haumea is made of ice and rock.
Haumea was discovered in March 2003 at the Sierra Nevada Observatory in Spain. The official announcement of its opening occurred in 2005. In the same year, its satellites were discovered.
It was originally designated as 2003 EL61. Haumea is named after the Hawaiian goddess of childbirth and fertility. Her companions are named after Haumea's daughters. Hi'iaka is the patron goddess of the island of Hawaii and hula dancers. Namaka is a water spirit in Hawaiian mythology.
Pluto's satellite - Charon
The moon Charon is almost half the size of Pluto. This small moon is so large that Pluto and Charon are sometimes called a double dwarf planetary system. The distance between them is 19,640 km (12,200 miles).
This new photograph of the region of Pluto's largest moon, Charon, reveals a unique feature: numerous depressions, which can be seen in the enlarged portion of the image on the right side.
The Hubble Space Telescope photographed Pluto and Charon in 1994, when Pluto was about 30 AU away. from the earth. These photographs showed that Charon is grayer than Pluto (which has a red tint), indicating that they have different surface compositions and structures.
A high-resolution image of Charon taken from the Long Range Reconnaissance Imager on NASA's New Horizons spacecraft at its closest approach to the surface on July 14, 2015, with an enlarged color image from the Ralph/Multispectral Visual Imaging Camera (MVIC) superimposed.
A full revolution of Charon around Pluto takes 6.4 Earth days, and one revolution of Pluto (1 day on Pluto) takes 6.4 Earth days. Charon neither rises nor descends in the system's orbit. Pluto always stands on the same side of Charon - this is called tidal capture. Compared to most planets and moons, the Pluto-Charon system is tilted on its side, as is Uranus. Pluto's orbit is retrograde: it rotates in the opposite direction, from east to west (Uranus and Venus also have retrograde orbits).
Charon was discovered in 1978 when sharp-eyed astronomer James Christie noticed that images of Pluto were strangely elongated. The drop seemed to be spinning around Pluto. The direction of elongation is cyclical back and forth for 6.39 days - the rotation period of Pluto. Searching through archives of images of Pluto taken several years ago, Christie found more instances where Pluto appeared elongated. Additional images confirmed that he had discovered Pluto's first known moon.
Christie proposed the name Charon in honor of the mythological ferryman who carried souls across the River Acheron, one of the five mythical rivers that surrounded the underworld of Pluto. Besides the mythological connection for this name, Christie chose it because the first four letters also correspond to his wife's name, Charlene.
July 1st, 2015
The centuries-long search for the boundaries of the solar system has repeatedly redrawn the harmonious picture of the universe, forcing scientists to offer ever new hypotheses as to why the Sun has so many satellites and planets. First, astronomers discovered that in addition to large planets, there are thousands of small cosmic bodies in the Solar System. They form the asteroid belt located inside the orbit of Jupiter. Then Pluto, Sedna, Orcus, Quaoar, Varuna and many other objects were discovered, revolving around the Sun at distances tens and hundreds of times greater than Jupiter. The so-called Kuiper belt, in which the above-mentioned celestial bodies are located, discovered at the end of the 20th century, destroyed the existing system of views, as a result, a number of astronomers even proposed depriving Pluto of its planetary status. Remember, we recently discussed a dispute about
Let's remember the history of these discoveries...
Planets are celestial bodies that revolve around the Sun, have sufficient weight and size, a spherical shape, and are capable of clearing their orbit of small cosmic bodies. In 2006, members of the International Astronomical Union decided that there are eight planets in the solar system: Venus, Mercury, Earth, Jupiter, Mars, Saturn, Neptune and Uranus.
In contrast to this concept, there is the term “dwarf planet,” which is understood as a celestial body that also revolves around the Sun, has the weight and shape to take the shape of a ball, but is not capable of clearing its orbit and is not a satellite.
Scientists, after conducting research, came to the conclusion that in ancient times, in the early stages of the existence of the Solar System, there were dwarf planets in it. The first objects of the system were formed a little more than 4.5 billion years ago from a cloud of gas and dust. Then, for the first three million years, small objects revolved around the Sun, colliding with each other and being destroyed. The remains of these objects today are presented in the form of ancient asteroids.
An international team of research scientists, using an ultra-sensitive magnetometer, studied samples of ancient meteorites. Scientists have established the origin of the magnetic field of these objects: as it turned out, it arose as a result of magnetization in a more powerful field. From all this we can conclude that the first bodies of the Solar system, under the outer shell, had a hot metal core, because it is the liquid metal in motion that creates the planet’s magnetic field.
The first objects reached approximately 160 kilometers in diameter. Thus, in order for a magnetic field to arise sufficient to magnetize the minerals of the outer layer, the metal had to move quite rapidly. That is, it turns out that the ancient planets of the solar system were much more like modern planets than was previously thought.
In addition to Pluto, there are many small dwarf planets in the Solar System, which are called asteroids, or minor planets.
The most significant of these small planets is Ceres, with a diameter of 770 kilometers. It is smaller in size than the Moon by the same amount as the Moon is smaller than the planet Earth.
Ceres was discovered on January 1, 1801. Italian astronomer Giuseppe Piazzi discovered a star that was behaving strangely. During his research, he discovered that this star was moving slowly in relation to other stars. The astronomer came to the conclusion that he had discovered a new planet. A little later, the German astronomer and mathematician Carl Gauss calculated the orbit of Ceres. It turned out that it was located between the orbits of Jupiter and Mars, exactly in the place where another planet should have been located. Of course, this was a big victory, because scientists finally managed to find the long-predicted planet.
A year later, in 1802, scientists were even more surprised when, in approximately the same place, German astronomer Heinrich Olbers discovered the planet Pallas. Two years later, another planet was discovered - Juno, and in 1807 - Vesta. Then, for forty years, scientists were unable to find new space objects, and only in 1845 the planet Astraea was discovered, and in 1847 - Hebe, Iris and Flora. By the end of the century, scientists had discovered approximately four hundred small planets.
In 1920, scientists discovered the asteroid Hidalgo, which moves through the orbit of Jupiter and passes relatively close to the orbit of Saturn. This asteroid is also remarkable in that it is the only known planet to have a very elongated orbit, which is inclined to the plane of the Earth’s orbit at an angle of 43 degrees. This small planet was named in honor of the famous hero of the Mexican revolution, Hidalgo y Castilla, who died in 1811.
In 1936, the zone of dwarf planets was replenished with new objects. Then the asteroid Adonis was discovered. The peculiarity of this small planet was that it departs from the Sun at the most distant point at the distance of Jupiter, and at the closest point it approaches the orbit of Mercury.
In 1949, Icarus was also discovered, a small planet that is removed from the Sun at its maximum point at a distance equal to two radii of the Earth's orbit. The minimum distance of a planet is equal to one-fifth of the distance from our planet to the Sun. It is noteworthy that none of the known planets approaches the Sun at such a close distance. In fact, this is where the name comes from (remember the legend of Icarus).
According to scientists, there are currently about 40-50 thousand small planets in the Solar System. But of this entire set, only a small part can be explored using astronomical instruments.
If we talk about the sizes of small planets, they are quite diverse. There are few planets approximately equal in size to Pallas or Ceres (they reach approximately 490 kilometers in diameter). About seventy planets have a diameter of about 100 kilometers. Most dwarfs reach a size of 20-40 kilometers in diameter, but there are also those that have a diameter of about 2-3 kilometers. Despite the fact that not all asteroids have yet been discovered and studied, we can already say that their total mass is approximately one thousandth of the mass of the Earth. But this is only for now, because scientists believe that no more than five percent of the total number of asteroids that are available for research with modern equipment have currently been discovered.
Of course, one might assume that the physical features of asteroids are approximately the same, but in fact, scientists are faced with a great deal of diversity. In particular, in a study of the reflectivity of asteroids, it was discovered that Pallas and Ceres reflect light like terrestrial rocks, Juno - like light rocks, and Vesta reflects light like white clouds. This is very interesting, because asteroids are so small that they are not able to retain an atmosphere near them. Thus, asteroids have no atmosphere and reflectivity depends directly on the materials that make up the surface of these planets. And yet, in some cases there is a fluctuation in brightness, which may indicate that these planets have an irregular shape and rotate around their axis.
By the end of the last century, astronomers had discovered about 20 thousand small planets or asteroids. In total, astronomers read, there are about a million asteroids in space, the size of which exceeds one kilometer, and which may be of interest to science.
Three types of planets
The great planetographic discovery - the discovery of the outer asteroid belt, located beyond the orbit of Neptune - significantly changed the understanding of the solar system. On the scale of our planet, such an event would correspond to the discovery of a previously unknown continent. A new look has emerged at the structure of the planetary system, which previously seemed not entirely harmonious, since it had a “strange” planet - the farthest, ninth from the Sun - Pluto. It did not fit into the natural alternation of the eight previous planets. The four planets closest to the Sun (Mercury, Venus, Earth and Mars) belong to the so-called terrestrial type - they are relatively small, but “heavy”, composed mainly of rocks, and some even have an iron core. The next four planets (Jupiter, Saturn, Uranus and Neptune) are called giant planets - they are very large, several times larger than Earth, and “light”, consisting mainly of gases. Even further away is Pluto, which is not like the planets of the first and second groups. It is significantly smaller than the Moon and consists mainly of ice. Pluto also differs in the nature of its movement: if the first eight planets move around the Sun in almost circular orbits located in the same plane, then this planet’s orbit is very elongated and highly inclined.
So Pluto would have been an “outcast” of the solar system if in the last five years it had not found a worthy company: a completely new, third, type of planetary body - icy planetoids. As a result, it became just one of the objects in the outer asteroid belt. Thus, the inner, or main, asteroid belt, located between Mars and Jupiter, ceased to be a unique formation and it acquired an “ice brother”, the so-called Kuiper belt. This structure of the Solar system agrees well with modern ideas about the formation of planets from a protoplanetary cloud of matter. In the hottest region near the Sun, refractory materials remained - metals and rocks, from which terrestrial planets were formed. The gases escaped to a cooler, more distant region, where they condensed into giant planets. Some of the gases that ended up at the very edge, in the coldest region, turned into ice, forming many tiny planetoids, since there was little substance on the outskirts of the protoplanetary cloud. In addition to the planets, comets were formed from this cloud, whose trajectories penetrate all three regions, as well as satellites orbiting the planets, cosmic dust and small stones - fragments of asteroids that plow through airless space and sometimes fall to Earth in the form of meteorites.
Ice belt
In 1930, when Pluto was discovered, the orbit of this planet began to be considered the boundary of the solar system, since only stray comets fly beyond its boundaries. It was believed that Pluto carried out his border duty completely alone. This was the thinking until 1992, when asteroid 1992 QB1 was discovered beyond the orbit of Pluto, but not too far from it. This event was the beginning of subsequent discoveries. The creation of new powerful telescopes on Earth and the launch of several space telescopes have contributed to the identification of many small objects on the outskirts of the Solar System that previously could not be seen. The “shock five-year period” was the period from 1999 to 2003, during which about 800 previously unknown asteroids were discovered. It became obvious that Pluto has a huge family consisting of thousands of small celestial bodies.
The outer asteroid belt, located beyond the orbit of Neptune, is most often called the Kuiper belt in honor of the American astronomer Gerard Peter Kuiper (1905-1973), who studied the Moon and planets of the Solar System. However, assigning his name to the outer asteroid belt seems very strange. The fact is that Kuiper believed that all small planets, if they were ever located near the orbit of Pluto, should have shifted to very distant regions, and the space immediately adjacent to Pluto should have been free of cosmic bodies. As for the assumption about the existence of numerous small icy asteroids beyond the orbit of Neptune (indistinguishable in telescopes of that time), it was repeatedly expressed from 1930 to 1980 by other astronomers - the Americans Leonard and Whipple, the Irishman Edgeworth, and the Uruguayan Fernandez. Nevertheless, the name of Kuiper was somehow firmly “stuck” to this asteroid belt, who denied the very possibility of its existence. The International Astronomical Union recommends calling outer belt asteroids simply trans-Neptunian objects, that is, located beyond the orbit of the eighth planet - Neptune. This designation corresponds to the geography of the solar system and is in no way connected with any scientific hypotheses of past years.
Kuiper inhabitants
There are now about 1,000 known Kuiper Belt asteroids, most of which are several hundred kilometers across, with the ten largest having a diameter of more than 1,000 km. Nevertheless, the total mass of these bodies is small - if you “blind” one ball out of them, then it will be equal in volume to 2/3 of the Moon. Small satellites orbit around 14 asteroids. It is believed that in total there are about 500 thousand asteroids larger than 30 km in the Kuiper belt. The area of the Kuiper belt is one and a half times larger than the part of the solar system around which it is located, that is, limited by the orbit of Neptune. It is not yet known what the asteroids in the Kuiper belt are made of, but it is clear that ice of various types (water, nitrogen, methane, ammonia, methanol - alcohol, carbon dioxide - “dry ice”, etc.) must play a major role in their structure, since The temperature in this region extremely far from the Sun is very low. In such a natural “freezer” the substance from which the planets of the solar system were formed in the distant past could be preserved unchanged.
More than 90% of new objects move in almost circular “classical” orbits located at distances from 30 to 50 astronomical units from the Sun. Many of the orbits are strongly inclined to the plane of the Solar System; 20 asteroids have an inclination exceeding 40°, and some even reach 90°. Therefore, the outline of the Kuiper belt looks like a thick donut, within which thousands of small celestial bodies move. The outer boundary of the belt is at a distance of 47 a. e. from the Sun is expressed very sharply, so there was an assumption that there was a fairly large planetary object there, perhaps even the size of Mars (that is, half the size of the Earth), whose gravitational influence does not allow the asteroids to “scatter.” The search for this hypothetical planet is currently underway. However, the outer boundary of the belt does not serve as an insurmountable barrier, and 43 asteroids (4% of their known number) go beyond it into an area of almost absolute cold and darkness, following highly elongated orbits extending over distances of more than 100 astronomical units (15 billion km ) from the sun.
Year after year, the idea of Pluto's role in the solar system has changed, and it is now seen as the leader of the icy dwarf planets of the Kuiper belt. A group of two hundred asteroids, whose orbital arrangement and motion speeds practically coincide with the same characteristics of Pluto, were even allocated to a special family called “plutinos,” that is, “plutonians.”
The outer edge of the Kuiper belt, sharply outlined at a distance of 47 AU. from the Sun, could well be called the new boundary of the solar system. However, some of the icy asteroids move beyond this limit. In addition, there is a magnetic field around the Sun that extends to about 100 AU. e. This area is called the heliosphere - the sphere of the Sun's magnetic field.
Dwarf planet or giant asteroid?
Since 1992, the number of asteroids discovered on the outskirts of the Solar System has increased and it has gradually become clearer that Pluto is not an independent planet, but only the largest representative of the outer asteroid belt. Thunder struck in 1999, when it was proposed to assign a serial number to Pluto, which every asteroid has. A suitable reason was also found - the number of numbered objects was approaching ten thousand, so they wanted to transfer Pluto from planets to asteroids with honor, assigning it the “remarkable” number 10,000. The discussion flared up immediately - some astronomers were for this proposal, others were sharply against it. As a result, Pluto was left alone for a while, and the “honorary” number went to another ordinary asteroid. However, in 2005, discussions about the status of Pluto flared up with renewed vigor. The discovery of another asteroid in the Kuiper belt by Michael Brown's group at the Palomar Observatory in the USA added fuel to the fire. This object, which was given the designation 2003 UB313, turned out to be not ordinary, but quite large. It is now considered most likely that the new object has a diameter of 2,800 km, while Pluto is 2,390 km. However, data on the new asteroid has yet to be clarified in more reliable ways. For example, wait until it passes against the background of a distant star and obscures its light. Based on the time between the disappearance and appearance of the star, it will be possible to determine the diameter of the asteroid very accurately. True, such astronomical events rarely happen, and all that remains is to wait for the right moment.
The discoverers said that if the new asteroid is larger than the planet Pluto, then it should also be considered a planet. At the same time, they said that if Pluto had been discovered not in 1930, but now, then the question of its classification would not even have arisen - it would certainly have been classified as an asteroid. However, history is history, and Pluto’s belonging to the planets has become not so much an astronomical, but rather a general cultural phenomenon, so the question of transferring Pluto to asteroids encounters quite strong resistance.
The new large object had to be given its own name, and this is where the discoverers encountered a serious difficulty. If it is a planet, then according to the rules of the International Astronomical Union (IAU) and in accordance with tradition, it should receive the name of a deity from classical Greco-Roman mythology, and if it is an asteroid, then it should be named after a mythological figure associated with the underworld ruled by Pluto . True, Brown’s group found a witty way out of this situation by proposing to name the new “giant asteroid” Persephone - the name of Pluto’s wife in Greek mythology. This name meets all the rules. But here an obstacle of a purely bureaucratic nature arose: one IAU working group is in charge of the planets, and another is in charge of asteroids. The dispute reached such intensity that a special committee of 19 astronomers from different countries was formed to decide whether the object 2003 UB313 should be considered a planet.
The members of this committee have been unable to come to a consensus for several months now. In the end, the desperate chairman, British astronomer Ivan Williams (who, by the way, claims that his name is typically Welsh, characteristic of a native of Wales), found a simple way out of the impasse, declaring that if an agreed conclusion could not be reached in the near future, then he will not go the scientific route, but will conduct the most ordinary vote, and the issue will be resolved by a simple majority of votes.
The most distant planetoid
The new idea that Pluto belongs not so much to planets as to asteroids has not yet been established, but has already found many adherents. It seemed that harmony had been found in the arrangement of the planets, which was not hampered by the presence of the “extra” ninth planet. However, the discoveries of new planetoids continued and on March 15, 2004 led to another violation of the harmony among the planets. On this day, a group of American astronomers, led by Michael Brown, announced that during observations at the high-altitude Palomar Observatory (California) in November 2003, they discovered the most distant object in the solar system. It turned out to be located 90 times farther from the Sun than the Earth, and 3 times further than the “farthest” planet Pluto. And such a gigantic distance turned out to be only the part of its orbit closest to the Sun. The diameter of this asteroid is smaller than that of Pluto - about 1,500 km. It was named Sedna after the sea mermaid, ruler of the cold and dark depths of the northern seas in Eskimo (Inuit) myths. Such a character was not chosen by chance - after all, this planetoid “dives” into the darkest and coldest region of the Solar System, moving away from the Sun 928 times further than the Earth and 19 times further than Pluto. None of the known asteroids go this far. Sedna immediately took the place of the “rogue planet” previously held by Pluto. Its highly elongated orbit again violated established ideas about the solar system.
It completes one revolution around the Sun in a monstrous period - 10,500 years! This planetoid is no longer classified as a member of the Kuiper belt, since even at its closest approach, Sedna is 1.5 times farther from the Sun than the outer boundary of this belt. The asteroid has become a kind of “Pluto of the 21st century” - an object whose role is unclear. It is constantly in complete darkness, and the Sun from its surface looks like a small star. Eternal cold reigns there. At the same time, the planetoid turned out to be painted in a rather intense red color and is second only to Mars in “redness”. It is unclear whether Sedna is alone or whether there are other planetoids at such a great distance - after all, the capabilities of telescopes make it possible to detect an object with a similar orbit only during 1% of the time of its revolution around the Sun, when it is at the closest part of its trajectory. For Sedna, such a period lasts about 100 years, and then it goes into a distant region for more than 10,000 years, and there an object of its size cannot be seen with modern telescopes.
AND . Remember also what this is The original article is on the website InfoGlaz.rf Link to the article from which this copy was made -
|– areas of the Solar System: where it is located, description and characteristics with photos, interesting facts, research, discovery, objects.
Kuiper Belt- a large accumulation of icy objects at the edge of our solar system. - a spherical formation in which comets and other objects are located.
After the discovery of Pluto in 1930, scientists began to assume that it was not the most distant object in the system. Over time, they noted the movements of other objects and in 1992 they found a new site. Let's look at some interesting facts about the Kuiper Belt.
Interesting facts about the Kuiper Belt
- The Kuiper Belt is capable of hosting hundreds of thousands of icy objects whose size varies between small fragments up to 100 km wide;
- Most short-period comets come from the Kuiper Belt. Their orbital period does not exceed 200 years;
- There may be more than a trillion comets lurking in the main part of the Kuiper Belt;
- The largest objects are Pluto, Quaoar, Makemake, Haumea, Ixion and Varuna;
- The first mission to the Kuiper Belt was launched in 2015. This is the New Horizons probe, which explored Pluto and Charon;
- Researchers have detected belt-like structures around other stars (HD 138664 and HD 53143);
- The ice in the belt formed during the creation of the Solar System. With their help you can understand the conditions of the early nebula;
Definition of the Kuiper Belt
We need to start the explanation with where the Kuiper Belt is located. It can be found beyond the orbit of the planet Neptune. Resembles the Asteroid Belt between Mars and Jupiter because it contains remnants from the formation of the Solar System. But in size it is 20-200 times larger than it. If not for the influence of Neptune, the fragments would have merged and were able to form planets.
Discovery and name of the Kuiper Belt
The presence of other objects was first announced by Freak Leonard, who called them ultra-Neptunian celestial bodies beyond Pluto. Then Armin Leuschner believed that Pluto could be just one of many long-period planetary objects that had yet to be found. Below are the largest Kuiper Belt objects.
Largest Kuiper Belt Objects |
| Name | Equatorial diameter |
Major axle, A. e. |
Perihelion, A. e. |
Aphelion, A. e. |
Circulation period around the Sun (years) |
Open |
|---|---|---|---|---|---|---|
| 2330 +10 / −10 . | 67,84 | 38,16 | 97,52 | 559 | 2003 i | |
| 2390 | 39,45 | 29,57 | 49,32 | 248 | 1930 i | |
| 1500 +400 / −200 | 45,48 | 38,22 | 52,75 | 307 | 2005 i | |
| ~1500 | 43,19 | 34,83 | 51,55 | 284 | 2005 i | |
| 1207 ± 3 | 39,45 | 29,57 | 49,32 | 248 | 1978 | |
| 2007 OR 10 | 875-1400 | 67,3 | 33,6 | 101,0 | 553 | 2007 i |
| Quaoar | ~1100 | 43,61 | 41,93 | 45,29 | 288 | 2002 i |
| Orc | 946,3 +74,1 / −72,3 | 39,22 | 30,39 | 48,05 | 246 | 2004 i |
| 2002 AW 197 | 940 | 47,1 | 41,0 | 53,3 | 323 | 2002 i |
| Varuna | 874 | 42,80 | 40,48 | 45,13 | 280 | 2000i |
| Ixion | < 822 | 39,70 | 30,04 | 49,36 | 250 | 2001 i |
| 2002 UX 25 | 681 +116 / −114 | 42,6 | 36,7 | 48,6 | 278 | 2002 i |
In 1943, Kenneth Edgeworth published an article. He wrote that the material beyond Neptune is too dispersed to coalesce into a larger body. In 1951, Gerard Kuiper entered the discussion. He writes about a disk that appeared at the beginning of the evolution of the Solar System. Everyone liked the belt idea because it explained where comets come from.
In 1980, Julio Fernandez determined that the Kuiper Belt is located at a distance of 35-50 AU. In 1988, computer models based on his calculations appeared, which showed that the Oort Cloud could not be responsible for all comets, so the Kuiper Belt idea made more sense.
In 1987, David Jewitt and Jane Lu began actively searching for objects using telescopes at the Whale Peak National Observatory and the Cerro Tololo Observatory. In 1992 they announced the 1992 QB1 and 6 months later the 1993 FW.
But many do not agree with this name, because Gerard Kuiper had something else in mind and all honors should be given to Fernandez. Due to the controversy that has arisen, scientific circles prefer to use the term “trans-Neptunian objects.”
Composition of the Kuiper Belt
What does the composition of the Kuiper Belt look like? Thousands of objects live on the territory of the belt, and in theory there are 100,000 with a diameter exceeding 100 km. They are all believed to be composed of ice - a mixture of light hydrocarbons, ammonia and water ice.
Water ice has been found on some sites, and in 2005 Michael Brown determined that 50,000 Quaoar contained water ice and ammonia hydrate. Both of these substances disappeared during the development of the solar system, which means there is tectonic activity on the object or a meteorite fall occurred.
Large celestial bodies were recorded in the belt: Quaoar, Makemake, Haumea, Orcus and Eridu. They were the reason why Pluto was relegated to the category of dwarf planets.
Exploring the Kuiper Belt
In 2006, NASA sent the New Horizons probe to Pluto. It arrived in 2015, demonstrating for the first time the “heart” of the dwarf and former planet 9. Now he goes towards the belt to examine its objects.
There is little information about the Kuiper belt, so it hides a huge number of comets. The most famous is Halley's comet with a periodicity of 16,000-200,000 years.
The Future of the Kuiper Belt
Gerard Kuiper believed that TNOs would not last forever. The belt spans approximately 45 degrees in the sky. There are many objects, and they constantly collide, turning into dust. Many believe that hundreds of millions of years will pass and nothing will remain of the belt. Let's hope the New Horizons mission gets there sooner! 
For thousands of years, humanity has watched the arrival of comets and tried to understand where they come from. If the ice cover evaporates when approaching a star, then they must be located at a great distance.
Over time, scientists came to the conclusion that beyond the planetary orbits there is a large cloud with ice and rocky bodies. It's called the Oort Cloud, but it still exists in theory because we can't see it.
Definition of the Oort Cloud
The Oort cloud is a theoretical spherical formation filled with icy objects. Located at a distance of 100,000 AU. from the Sun, which is why it covers interstellar space. Like the Kuiper belt, it is a repository of trans-Neptunian objects. Its existence was first discussed by Ernest Opik, who believed that comets could arrive from the region at the edge of the solar system.
In 1950, Jan Oort revived the concept and even managed to explain the principles of behavior of long-term comets. The existence of the cloud has not been proven, but it has been recognized in scientific circles.
Structure and composition of the Oort cloud
It is believed that the cloud can be located at 100,000-200,000 AU. from the sun. The composition of the Oort Cloud includes two parts: a spherical outer cloud (20000-50000 AU) and a disk inner cloud (2000-20000 AU). The outer one is home to trillions of bodies with a diameter of 1 km and billions of 20-kilometer ones. There is no information about the total mass. But if Halley's comet is a typical body, then the calculations lead to a figure of 3 x 10 25 kg (5 earths). Below is a drawing of the structure of the Oort Cloud.
Most comets are filled with water, ethane, ammonia, methane, hydrogen cyanide and carbon monoxide. 1-2% may consist of asteroid objects.
Origin of the Oort cloud
It is believed that the Oort Cloud is a remnant of the original protoplanetary disk that formed around the Sun star 4.6 billion years ago. The objects could have merged closer to the Sun, but due to contact with large gas giants they were pushed to great distances.
A study from NASA scientists has shown that the huge volume of cloud objects is the result of exchanges between the Sun and neighboring stars. Computer models show that galactic and stellar tides change cometary orbits, making them more circular. Perhaps this is why the Oort Cloud takes the shape of a sphere.
The simulations also confirm that the creation of the outer cloud is consistent with the idea that the Sun appeared in a cluster of 200-400 stars. Ancient objects may have influenced the formation because there were more of them and they collided more often.
Comets from the Oort Cloud
It is believed that these objects drift quietly in the Oort Cloud until they go out of their usual route due to a gravitational push. So they become long-period comets and visit the outer system.
