Solar system along with dwarf planets. Dwarf planets - an explanation for the kids
Dwarf planets
The term "dwarf planet" was adopted in 2006. This definition met with both approval and criticism, and is still disputed by some scientists. For example, as the simplest alternative, they propose a conditional division between planets and dwarf planets in size or even
Moons: if more then - planet, if less - planetoid. This term can only be applied to celestial objects located in.
A dwarf planet is a celestial body that has a number of distinctive features:
1. orbits around; 2. has a sufficient mass in order to maintain hydrostatic equilibrium under the influence of gravitational forces and have a nearly round shape; 3. is not a satellite of the planet; 4. does not dominate in its orbit (cannot clear space from other objects).
Five dwarf planets are officially recognized by the International Astronomical Union (IAU).
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However, it is possible that at least 40 more of the known objects in the world belong to this category. Scientists estimate that up to 200 dwarf planets can be found in the Kuiper belt and up to 2,000 dwarf planets beyond.
The sizes and masses that dwarf planets should have are not specified in the IAS decision. There are no strict upper limits. Even an object larger or more massive than Mercury with unrefined orbital surroundings can be classified as a dwarf planet. The lower limit is determined by the concept of a hydrostatically equilibrium shape, but the size and mass of an object that has reached this shape is unknown. Empirical observations suggest that they can vary greatly depending on the composition and history of the object. The primary source of the preliminary MAS solution determining the hydrostatic equilibrium shape is applied “to objects with a mass of more than 5 · 1020 kg and a diameter of more than 800 km”. The latter was not included in the final decision, although it was approved. According to some astronomers, the new definition means the addition of up to 45 new dwarf planets.Send your good work in the knowledge base is simple. Use the form below
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Introduction
2. Historical background
3. List of dwarf planets
4. Mass restrictions
8. Makemake
Conclusion
Bibliography
Application
Introduction
In this part of my essay, I would like to substantiate the reasons for my choice of the topic of dwarf planets.
It seemed to me that they [dwarf planets] are very similar to us eleventh graders: we are no longer small asteroids orbiting the Sun, but we are not yet planets with their own gravity. Perhaps such a comparison will seem too romantic to someone, but, nevertheless, it was this closeness and similarity that attracted me to this topic.
planet dwarf sign
1. Dwarf planet: term and signs
So what is a dwarf planet?
A dwarf planet, as defined by the International Astronomical Union, is a celestial body that:
Does not dominate in its orbit (cannot clear space from other objects).
2. Historical background
The term "dwarf planet" was adopted in 2006 as part of the classification of bodies orbiting the Sun into three categories. Bodies large enough to clear the vicinity of their orbit are defined as planets, and not large enough to even achieve hydrostatic equilibrium as small solar system bodies or asteroids. Dwarf planets occupy an intermediate position between these two categories. This definition met with both approval and criticism, and is still disputed by some scientists. For example, as the simplest alternative, they propose a conditional division between planets and dwarf planets according to the size of Mercury or even the Moon: if more then - a planet, if less - a planetoid.
In 2006, the IAU officially named three bodies, which immediately received the classification of dwarf planets - Ceres, Eris and Pluto. Later, two more objects were declared dwarf planets. The term "dwarf planet" should be distinguished from the concept "minor planet", which is called asteroids.
3. List of dwarf planets
Five dwarf planets are officially recognized by the International Astronomical Union: Ceres, Pluto, Haumea, Makemake, Eris; however, it is possible that at least another 40 of the known objects in the solar system belong to this category. Scientists estimate that up to 200 dwarf planets can be found in the Kuiper belt and up to 2,000 dwarf planets beyond. Because Pluto shares its orbital space with many other objects in the Kuiper Belt - a ring of ice debris beyond the orbit of Neptune - it is not included in the list of planets. Thus, Pluto has been classified as a dwarf planet. It is interesting that from this list only he [Pluto] was "demoted", becoming a dwarf planet and losing the status of a planet, and the rest, on the contrary, were "promoted", ceasing to be just one of the asteroids.
Three large objects at once in the asteroid belt (Vesta, Pallas and Hygea) will have to be classified as dwarf planets if it turns out that their shape is determined by hydrostatic equilibrium. To date, this has not been convincingly proven.
4. Mass restrictions
The lower and upper limits for the size and mass of dwarf planets are not specified in the IAU solution. There are no strict upper bounds, and an object larger or more massive than Mercury with unrefined orbital neighborhoods could be classified as a dwarf planet.
The lower limit is determined by the concept of a hydrostatically equilibrium shape, but the size and mass of an object that has reached this shape is unknown. Empirical observations suggest that they can vary greatly depending on the composition and history of the object. The original source of the preliminary IAS decision determining the hydrostatic equilibrium shape applies “to objects weighing more than 51,020 kg and a diameter of more than 800 km”, but this was not included in the final decision 5A, which was approved.
According to some astronomers, the new definition means the addition of up to 45 new dwarf planets.
Pluto was discovered by Clyde Tombaugh in 1930 while searching for the mysterious Planet X, which is disturbing the motion of Neptune in its orbit.
Initially, it was assumed that Pluto should be at least the size of the Earth, but now it is known that its diameter is only 2,352 kilometers - 5 times less than the Earth's, and its mass is only 0.2% of the Earth's.
Pluto has an extremely elongated elliptical orbit that is not in the same plane with the orbits of the eight planets of the solar system. On average, a dwarf planet revolves around the Sun at a distance of 5.87 billion kilometers, making one revolution in 248 years.
Due to its distance from the star, Pluto is one of the coldest places in our system. The temperature on its surface hovers around minus 225 degrees Celsius.
Pluto has 4 known moons: Charon, Nyx, Hydra, and the recently discovered tiny satellite, so far called P4 (the final name will probably be Cerberus). Nyx, Hydra and P4 are relatively small, while Charon is only half the size of Pluto itself, and the center of mass around which they revolve is outside their bodies. For this reason, most astronomers refer to them as a double dwarf planet.
Although Pluto is difficult to study due to its remoteness, scientists were able to calculate its approximate composition: it is 70% rock and 30% ice. The surface of the dwarf planet is covered mainly with frozen nitrogen. There is a very thin atmosphere stretching 3,000 kilometers into space and composed mostly of nitrogen, methane and carbon monoxide.
In a few years, Pluto will finally be well considered: NASA's New Horizons probe will fly near this dwarf planet in July 2015, revealing a world so cold and distant for the first time in history.
California Institute of Technology astronomer Mike Brown led the group of researchers who discovered Eris in 2005. The search was stimulated by the IAU's intention to classify Pluto as a newly created category of dwarf planets, which happened a year later.
The decision to give this dwarf planet such a name is still controversial. Eris is the Greek goddess of strife and enmity, who caused envy and jealousy among the goddesses, which led to the Trojan War. The only known moon of Eris was named after the daughter of the goddess - Dysnomia, who "worked" in the Pantheon as a spirit of lawlessness.
Eris is practically the same size as Pluto, but 25% more massive than it, which is explained by the high content of rocks in its composition and less ice. However, its surface also consists mainly of nitrogen ice.
Like Pluto, Eris has a high elliptical orbit. Eris is even more distant from the sun, its orbit is at an average distance of 10.1 billion kilometers from the star. One Eridani year is 557 years.
Huamea was discovered in the Kuiper belt just outside Pluto in late 2004 by Brown's team, and has become one of the most bizarre objects in the solar system.
This dwarf planet is 1,930 kilometers across, nearly the size of Pluto, but three times lighter than Pluto. This is mainly due to its non-spherical shape. Most of all, Huamea looks like an American football ball.
This dwarf planet makes one revolution on its axis in just 4 hours, which makes it also one of the fastest rotating bodies in our system. This ultra-high speed of rotation is responsible for the oblong shape of the dwarf planet.
Huamea, named after the Hawaiian goddess of childbirth, has two moons named after her daughters: Hiiaka and Namaka.
Recently, it was discovered that 75% of Huamea's surface is covered with crystallized water ice, similar to ice in a refrigerator freezer. It takes energy for ice to maintain this structured shape. Astronomers speculate that energy may come from the decay of radioactive elements inside Haumea, as well as from the heat released by tidal forces in gravitational interaction with its satellites. Huamea orbits the Sun in 283 years.
8. Makemake
Brown's team also discovered Makemake in 2005. Astronomers have not yet established the exact size of this dwarf planet, it is approximately three quarters the size of Pluto. Thus, this object becomes the third largest dwarf planet after Pluto and Eris.
Makemake is the second brightest Kuiper belt object after Pluto and can be seen even with a good amateur telescope. Like Huamea, Makemake is named after a Polynesian deity - this time after the creator of humanity and the god of fertility in the Rapanui pantheon, the indigenous inhabitants of Easter Island.
Like Pluto and Eris, Makemake appears reddish in the visible spectrum. Scientists believe that the surface of the dwarf planet is covered with frozen methane. Makemake has no satellites, which is unique among dwarf planets.
Ceres is the only dwarf planet outside the Kuiper belt. Its orbit passes through the asteroid belt between the orbits of Mars and Jupiter, making one revolution in 4.6 years.
Ceres is the largest object in the asteroid belt, and contains about a third of the entire mass of the belt. Meanwhile, at just 950 kilometers across, it is the smallest known dwarf planet. Ceres is the goddess of fertility and motherhood in ancient Roman mythology.
This dwarf planet was discovered much earlier than others due to its proximity. Italian astronomer Giuseppe Piazzi discovered it in 1801. For the next half century, astronomers believed it to be a real planet, until it became clear that it was just one of many objects in the asteroid belt.
Today, most astronomers classify Ceres as a protoplanet, believing that it could have grown into a full-fledged planet like Mars or Earth, if in ancient times Jupiter had not interrupted this process with its powerful gravity.
Scientists believe Ceres is composed of a rocky core surrounded by a thick mantle of water ice. Some researchers even suggest the existence of an ocean of liquid water under a layer of ice.
In a few years, the whole world will be able to learn a lot about this dwarf planet - in February 2015, NASA's Down (Dawn), currently orbiting the asteroid West, will arrive at Ceres to study it in detail.
In conclusion, I would like to summarize the most important information about dwarf planets:
A dwarf planet is a celestial body that:
Orbits the Sun;
Has a sufficient mass in order to maintain hydrostatic equilibrium under the influence of gravitational forces and have a nearly round shape;
It is not a satellite of the planet;
Does not dominate in its orbit (cannot clear space from other objects);
Five dwarf planets are officially recognized by the International Astronomical Union: Ceres, Pluto, Haumea, Makemake, Eris. Because Pluto shares its orbital space with many other objects in the Kuiper Belt - a ring of icy debris beyond Neptune's orbit - it is not listed as a planet. Thus, Pluto has been classified as a dwarf planet.
I hope this essay was informative and useful for all readers. After all, space is one of the most mysterious, unexplored and interesting topics for discussion. Moreover, as Fred Hoyle wrote, it's only an hour's drive to space if your car could drive vertically.
Bibliography
1.http: //ru.wikipedia.org/wiki/Dwarf_planet
2.http: //scienceevents.ru/posts/3689- dwarf- planets- solar-systems/
3.http: //www.lassy.ru/news/karlikovye_planety/2011-08-23-159
Application
Fig. 1 The order of the dwarf planets
Fig. 2 Dwarf planets in comparison with the Earth
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Dwarf planets are celestial bodies revolving around the Sun like the full-fledged eight planets, but also having some resemblance to asteroids.
According to the definition of the International Astronomical Union, dwarf planets are an intermediate link between planets and asteroids and must meet 4 requirements:
- orbit around the sun;
- have a sufficiently high mass in order to maintain hydrostatic equilibrium under the influence of their own gravity and have a spherical or close to such shape;
- not be a satellite of the planet;
- not the ability to clear the surroundings of its own orbit from other celestial bodies.
Dwarf planets of the solar system
At the moment, science knows only the small planets of the solar system. There are six of them. This is Ceres from the main asteroid belt between the orbits of Mars and Jupiter, and 5 planetoids or trans-Neptunian objects: Pluto, Haumea, Makemake, Eris and Sedna. All these bodies differ from each other as much as the 8 "big" planets.
Only 2 of them were fully investigated. is still in orbit of the nearest dwarf planet, Ceres, and has long managed to transmit the first photos of the dwarf planet. And the device on July 14, 2015 made a historical approach to the largest trans-Neptunian object Pluto, the photos arrived at Earth a few days later. The remaining 4 planetoids are still a mystery to us.
However, the question How many dwarf planets are in the solar system remains open. Already today, astronomers have 40 candidates located beyond the orbit of Neptune, further study of which may allow them to be attributed to this category. Other scientists are convinced that the total number of minor planets in the Kuiper belt, scattered disk and Oort cloud reaches at least 2,000.
Extrasolar Minor Planets
As for extrasolar small planets, they are unlikely to be discovered with the current generation of telescopes. And the point here is not even in the relatively modest sizes of such bodies, the catch lies in the 4th point of the definition, which in practice will be very difficult to verify in a distant planetary system. However, there is still some information about the existence of dwarf exoplanets, so according to one of the popular hypotheses, Sedna has an extrasolar origin and was captured by the gravity of our system 4 billion years ago.
Definition of the concept of dwarf planets according to international standards
The International Astronomical Union (IAU) has given a definition of space objects that will be called dwarfs. So planets that have the following signs are considered dwarf:
- The object revolves around the sun;
- The mass of the object is sufficient to become almost round;
- The object cannot, by its gravity, clear its path on its own.
The main differences between the dwarf and the terrestrial group of planets
The difference between these planets from the Terrestrial group lies in the inability of a space object to clear a path in front of itself, that is, others, such as or Mars, can, with their mass, clear a path in front of them in their orbit. Unlike large ones, these planets, as a rule, intersect with their orbits the places of accumulation of other cosmic bodies, for example, the Kuiper Belt.
To date, astronomers have managed to detect and classify five such objects:
- Pluto(the well-known planet, which at the IOC meeting in 2006, retrained from a planet to a dwarf one).
- Ceres Is a dwarf planet between Mars and Jupiter in the asteroid belt.
- Makemake- little studied, the third largest dwarf planet in front of the solar system.
- Haumea- unusual for very fast rotation around its axis.
- Eris- in terms of mass, it is the second dwarf planet after Pluto, although it is possible that the first data is being refined.
However, according to some scientists, it can contain about 100 or more small dwarf planets, they just haven't been found yet.
The International Astronomical Union designated the planets beyond the orbit of Neptune as "Plutoids".
So it is believed that Eris, which revolves around the Sun far beyond the orbit of Neptune, becomes rogue, and Ceres from the Asteroid Belt becomes a dwarf planet.
Table of dwarf planets with astronomical characteristics
| Dwarf planets | ||
| Location | Asteroid belt | |
| Dimensions (km) | 975 × 909 | |
| Weight in kg. Relative to earth | 9.5 10 20 0,00016 |
|
| 0,0738 471 |
||
| 0,51 | ||
| Rotation period (days) | 0,3781 | |
| 0 | ||
| opening date | 01.01.1801 | |
| Pluto | Location | Kuiper Belt |
| Dimensions (km) | 2306 ± 20 | |
| Weight in kg. Relative to earth | 1.305 10 22 0,0022 |
|
| Average equatorial radius in km | 0,180 1148,07 |
|
| First space velocity (km / s) | 1,2 | |
| Rotation period (days) | −6.38718 (retrograde) | |
| Number of known satellites | 5 | |
| opening date | 18.02.1930 | |
| Makemake | Location | Kuiper Belt |
| Dimensions (km) | 1500 × 1420 | |
| Weight in kg. Relative to earth | ? | |
| Average equatorial radius in km | ? | |
| First space velocity (km / s) | ? | |
| Rotation period (days) | 0.32 | |
| Number of known satellites | 1 | |
| opening date | 31.03.2005 | |
| Eris | Location | Scattered disc |
| Dimensions (km) | 2326 ± 12 | |
| Weight in kg. Relative to earth | ~ 1.67 1022 0,0028 |
|
| Average equatorial radius in km | 0,19 ~1300 |
|
| First space velocity (km / s) | 1.3 | |
| Rotation period (days) | ≈ 1 (0.75–1.4) | |
| Number of known satellites | 1 | |
| opening date | 5.01.2005 | |
| Haumea | Location | Kuiper Belt |
| Dimensions (km) | 1960 × 1518 × 996 | |
| Weight in kg. Relative to earth | 4.2 1021 0,0007 |
|
| Average equatorial radius in km | ~750 | |
| First space velocity (km / s) | 0.84 | |
| Rotation period (days) | 0.16 | |
| Number of known satellites | 2 | |
| opening date | 28.12.2004 | |
| Sedna | Location | Oort Cloud |
| Dimensions (km) | 995 ± 80 | |
| Weight in kg. Relative to earth | 8.3 1020 - 7.0 1021 | |
| Average equatorial radius in km | ? | |
| First space velocity (km / s) | ? | |
| Rotation period (days) | 0.42 d (10 h) | |
| Number of known satellites | 0 | |
| opening date | 14.11.2003 | |
Other candidates for the title of dwarf planet
Thanks to modern means of detection, scientists have discovered several dozen large cosmic bodies that can be attributed and qualified to the "Plutoids" planets. The table below shows planetoids with an approximate diameter of up to 600 km. Moreover, the first 6 objects are likely to become the main candidates.
| Name | Category | Diameter | Weight |
|---|---|---|---|
| 2015 KH 162 | Cubivano in the Kuiper Belt | 400-800 km | unknown |
| 2007 OR 10 | Scattered Disc Object | ~ 1535 km | unknown |
| Quavar | Cubivano in the Kuiper Belt | 1074-1170 km | 1.0-2.6 10 21 kg |
| 2002 MS 4 | Cubivano in the Kuiper Belt | ~ 934 km | unknown |
| Orc | Pluto in the Kuiper Belt | 917-946 km | 6.2-7.0 10 20 kg |
| Salacia | Cubivano in the Kuiper Belt | ~ 921 km | 4.5 10 20 |
| 2013 FY 27 | Scattered Disc Object | ~ 733 km | unknown |
| Varuna | Cubivano in the Kuiper Belt | 722 km | ~ 5.9 10 20 kg |
| 2002 UX 25 | Cubivano in the Kuiper Belt | 681-910 km | ~ 7.9 10 20 kg |
| Ixion | Pluto in the Kuiper Belt | ~ 650 km | 5.8 10 20 |
| 2002 AW 197 | Cubivano in the Kuiper Belt | 626-850 km | ~ 4.1 10 20 kg |
| 2005 UQ 513 | Cubivano in the Kuiper Belt | 550-1240 km | unknown |
| Warda | Cubivano in the Kuiper Belt | 500-1130 km | ~ 6.1 10 20 kg |
| 2005 RN 43 | Cubivano in the Kuiper Belt | ~ 730 km | unknown |
| 2003 VS 2 | Pluto in the Kuiper Belt | ~ 725 km | unknown |
| 2007 JJ 43 | Unknown(Kuiper belt) | 609-730 km | unknown |
| 2004 GV 9 | Cubivano in the Kuiper Belt | ~ 677 km | unknown |
| 2002 TC 302 | Scattered Disc Object | 590-1145 km | 1.5 10 21 |
| 2003 AZ 84 | Pluto in the Kuiper Belt | 573-727 km | unknown |
| 2004 XA 192 | Cubivano in the Kuiper Belt | 420-940 km | unknown |
| 2010 RE 64 | Cubivano in the Kuiper Belt | 380-860 km | unknown |
| 2010 RF 43 | Cubivano in the Kuiper Belt | ~ 613 km | unknown |
| Chaos | Cubivano in the Kuiper Belt | ~ 600 km | unknown |
| 2007 UK 126 | Scattered Disc Object | ~ 600 km | unknown |
| 2003 UZ 413 | Cubivano in the Kuiper Belt | ~ 591 km | unknown |
| 2006 QH 181 | Scattered Disc Object | 460-1030 km | unknown |
| 2010 EK 139 | Scattered Disc Object | 470-1000 km | unknown |
| 2010 KZ 39 | Scattered Disc Object | 440-980 km | unknown |
| 2001 UR 163 | Scattered Disc Object | ~ 636 km | unknown |
| 2010 FX 86 | Scattered Disc Object | ~ 598 km | unknown |
| 2013 FZ 27 | Scattered Disc Object | ~ 595 km | unknown |
| 2012 VP 113 | Scattered Disc Object | ~ 595 km | unknown |
| 2008 ST 291 | Scattered Disc Object | ~ 583 km | unknown |
| 2005 RM 43 | Scattered Disc Object | ~ 580 km | unknown |
| 1996 TL 66 | Scattered Disc Object | ~ 575 km | 2 10 20 |
| 2004 XR 190 Buffy | Scattered Disc Object | 425-850 km | 0.6-4.8 10 20 |
| 2004 NT 33 | Cubivano in the Kuiper Belt | 423-580 km | unknown |
| 2004 UM 33 | Cubivano in the Kuiper Belt | 340-770 km | unknown |
| 2002 XW 93 | Scattered Disc Object | 565-584 km | unknown |
| 2004 TY 364 | Cubivano in the Kuiper Belt | ~ 554 km | unknown |
| 2002 XV 93 | Pluto in the Kuiper Belt | ~ 549 km | unknown |
According to the 2006 IAU definition, a dwarf planet is “a celestial body orbiting a star that is massive enough to be rounded off by its own gravity, but does not clear planetesimals from the nearest region, and is not a satellite. In addition, it must have sufficient mass to overcome the compressive strength and achieve hydrostatic equilibrium. "
Essentially, the term refers to any planetary mass object that is neither a planet nor a natural satellite that meets two basic criteria. First, it must be in direct orbit of the Sun and not be the moon around another body. Secondly, it must be massive enough to take on a spherical shape under the influence of its own gravity. And, unlike a planet, it doesn't have to clear the surroundings around its orbit.
Size and weight
For a body to round, it must be massive enough for gravity to become the dominant force affecting the shape of the body. The internal pressure generated by this mass will cause the surface to become plastic, smooth out high rises and fill in depressions. Small bodies less than a kilometer in diameter do not do this (like asteroids), they are controlled by forces outside their own gravitational forces, which tend to maintain irregular shapes.
The largest known trans-Neptunian objects (TNO)
Meanwhile, bodies several kilometers across - when gravity is significant, but not dominant - take the shape of a spheroid or "potato". The larger the body, the higher its internal pressure until it becomes sufficient to overcome the internal compressive force and achieve hydrostatic equilibrium. At this point, the body becomes as round as it can possibly be, given its rotation and tidal effects. This is the definition of the limit of a dwarf planet.
However, rotation can also affect the shape of the dwarf planet. If the body does not rotate, it will be a sphere. The faster it spins, the more elongated or versatile it will become. An extreme example of this is Haumea, which is almost twice as long on the main axis as at the poles. The tidal forces also cause the rotation of the body to gradually become tidally blocked, and the body remains facing the companion with one side. An extreme example of such a system is Pluto - Charon, both bodies are tidally locked between each other.
The IAU does not determine the upper and lower limits for the size and mass of dwarf planets. Although the lower limit is determined by the achievement of an equilibrium hydrostatic shape, the size or mass at which this object reaches that shape depends on its composition and thermal history.
For example, bodies made of hard silicates (like rocky asteroids) must reach hydrostatic equilibrium with a diameter of about 600 kilometers and a mass of 3.4 x 10 ^ 20 kg. For a less rigid body made of water ice, this limit will be closer to 320 km and 10 ^ 19 kg. As a result, there is currently no specific standard for defining a dwarf planet based on its size or mass, but instead it is usually defined based on its shape.
Orbital position
In addition to hydrostatic equilibrium, many astronomers have insisted on drawing a line between planets and dwarf planets on the basis of their inability to "clear the vicinity of their orbit." In short, planets can remove smaller bodies near their orbits through collision, capture, or gravitational disturbance, whereas dwarf planets do not have the necessary mass to achieve this.
To calculate the likelihood that a planet will clear its orbit, planetary scientists Alan Stern and Harold Levinson presented a parameter that they denote by the letter "lambda".
This parameter expresses the probability of a collision depending on the given deviation of the object's orbit. The value of this parameter in the Stern model is proportional to the square of the mass and inversely proportional to the time and can be used to estimate the potential of a body to clear the vicinity of its orbit.
Astronomers like Stephen Soter, a New York University scientist and a fellow at the American Museum of Natural History, suggest using this parameter to draw a line between planets and dwarf planets. Soter also proposed a parameter he calls the planetary discriminant - denoted by the letter mu - that is calculated by dividing the mass of a body by the total mass of other objects in the same orbit.
Recognized and possible dwarf planets
There are currently five dwarf planets: Pluto, Eris, Makemake, Haumea, and Ceres. Ceres and Pluto alone have been observed enough to be indisputably in this category. The IAU ruled that unnamed trans-Neptunian objects (TNOs) with an absolute magnitude brighter than +1 (and mathematically limited to a minimum diameter of 838 km) should be classified as dwarf planets. 
Potential candidates currently under consideration include Orc, 2002 MS4, Salazia, Kwavar, 2007 OR10, and Sedna. All of these objects are located in the Kuiper belt; with the exception of Sedna, which is considered separately - a separate class of dynamic TNOs in the outer solar system.
It is possible that there are 40 more objects in the solar system that can rightly be designated dwarf planets. It is estimated that up to 200 dwarf planets can be found in the Kuiper belt after studying it, and beyond this belt, their number could exceed 10,000.
Disagreements
Immediately after the decision of the IAU regarding the definition of the planet, a number of scientists expressed their disagreement. Mike Brown (leader of the Caltech group that discovered Eris) agrees to reduce the number of planets to eight. However, a number of astronomers like Alan Stern have discussed the definition of the IAS.
Stern argues that, like Pluto, Earth, Mars, and Neptune also do not completely clear their orbital zones. The Earth revolves around the Sun with 10,000 near-Earth asteroids, which Stern estimates contradict the clearing of the Earth's orbit. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path.
In 2011, Stern referred to Pluto as a planet and considered other dwarf planets like Ceres and Eris, as well as large moons, to be complementary planets. However, other astronomers argue that although large planets do not clear their orbits, they have complete control over the orbits of other bodies within their orbital zone.
Another controversial application of the new definition of planets concerns planets outside the solar system. Methods for detecting extrasolar objects do not directly determine whether the object clears the orbit, only indirectly. As a result, in 2001, the IAU approved separate "working" definitions for extrasolar planets, including this dubious criterion: "The minimum mass / size required to consider an extrasolar object a planet must match the parameters accepted for the solar system."
Although not all members of the IAU were in favor of adopting this definition of planets and dwarf planets, NASA recently announced that it will use the new guidelines set by the IAU. Nevertheless, the debate about the 2006 decision has not yet stopped, and we can well expect further developments on this front, when more "dwarf planets" are discovered and identified.
It is fairly easy to define a dwarf planet by IAU standards, but fitting the solar system into a three-tier classification system will become more difficult as our understanding of the universe expands.
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