For a long time, scientists believed that the number of planets in the solar system was limited to nine. However, the situation in the world of astronomy changed in 2006. Then one of the planets - Pluto - lost its status and became known as a dwarf. There are now hundreds of planets in the solar system that can be assigned to this group. But scientists believe that there are only five dwarf planets - Pluto, Ceres, Makemake, Eris and Haumea.

Pluto is the most famous dwarf planet

Pluto is located at a distance of 6 billion kilometers from the Sun. The planet was discovered quite by accident by an explorer named Clyde William Tombaugh. However, the existence of Pluto was hypothesized by the scientist Percival Lovell 15 years before its discovery. Pluto is the coldest celestial body in the solar system. The temperature on its surface is -223 degrees Celsius. Pluto, now classified as a dwarf planet, has a diameter of 2374 km.

The surface of Pluto is covered with dark and light stripes. It is believed that they are deposits of methane frost. Dark streaks are older gas deposits. According to scientists, the entire planet is covered with a layer of methane ice. That is why the temperature on its surface does not exceed -230 degrees Celsius.

The atmosphere of Pluto is entirely composed of three chemicals - the gases argon, methane and neon, and is divided into two parts, between which there is an aerosol layer. Even in summer, the temperature of the planet does not rise above -209 degrees Celsius.

Research on trans-Neptunian objects

Astronomers who have studied Neptune have always suspected that the sky above it is not as “clear” as it might seem at first glance. Scientists believed that a belt of yet unexplored celestial bodies is located above it. The discovery took place in 1992 - then for the first time astronomers managed to observe a new object, later classified as a "dwarf planet". Already next year, a similar planet was found, and by 1996 the number of discovered celestial bodies was 32. Currently, astronomers have discovered more than a thousand so-called trans-Neptunian objects.

Scientists have named this group the Kuiper belt. At least one of this category is larger than Pluto. This is the small planet Eris. Then the researchers faced a choice: it was necessary either to include in the list of planets of the solar system a huge number of objects - more than a thousand; or deprive Pluto of the status of a planet. Ultimately, astronomers chose the latter path, highlighting these small celestial bodies in a separate category - dwarf planets.

Eris - a planet named after the goddess of enmity

After scientists named Pluto a dwarf planet in 2006, the debate over this decision has not ceased to subside. The name of the celestial body, which was discovered by astronomer Michael Brown from California, is the most appropriate for the current situation. In ancient Greek mythology, Eris was the goddess of discord and quarrels. It was she who provoked jealousy among the Olympian gods, which led to the Trojan War. The dwarf planets of the solar system also provoke a lot of controversy between astronomers.

The planet has a single satellite - a celestial body called Dysnomia. This planet is named after the daughter of the ancient Greek goddess, who in mythology was the spirit of lawlessness. In terms of its physical size, Eris does not exceed Pluto. But it is a quarter more massive than the planet that lost its status. Eris makes its revolution around the Sun in 557 years.

Dwarf planet Haumea

How many dwarf planets are in the solar system? The International Union of Astronomers has recognized this status for five planets: in addition to Pluto and Eris, these are Ceres, Makemake and Haumea. However, presumably about 40 more objects scientists refer to this group.

The dwarf planet Haumea was discovered by astronomer Brown in 2004. In its transverse diameter, which ranges from 1212-1491 km, Haumea can be compared with Pluto. But this dwarf planet is not round, but more elongated, reminiscent of its contours of the ball used in American football. Haumea rotates around its axis in 4 hours. The planet is named after the Hawaiian goddess of fertility. Three quarters of its surface is covered with a layer of ice. The dwarf planet makes a revolution around the Sun in 283 years.

Planet Makemake

In 2005, astronomers from Brown's team, who were studying minor dwarf planets, made another discovery. This time it was a planet named Makemake. The celestial body was named after the deity of fertility, which was revered in Polynesia. Its orbit is even further away than Pluto. It takes Makemake one revolution around the Sun in 310 years. The dwarf planet is the second brightest planet in the entire Kuiper Belt. Scientists believe that Makemake is also covered in a thick layer of frozen methane.

Ceres is a dwarf planet discovered earlier than others

Many are interested in which planet is a dwarf, but does not belong to the Kuiper belt? This is Ceres, whose orbit of rotation is between Mars and Jupiter. Ceres makes a revolution around the main luminary of the solar system in 4.6 years. It is the largest celestial body in the asteroid belt. The dwarf planet is named after the ancient Roman goddess, who personified maternal love, as well as fertility. It was opened quite a long time ago - in 1801. It was discovered by the Italian scientist Giuseppe Piazzi. Modern astronomers believe that Ceres is a rocky core, which is covered with a mantle of water and ice.

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 dwarf planets are considered that have the following features:

• The object revolves around the sun;
• The mass of the object is sufficient to become almost round;
• An object cannot use its gravity to clear its path on its own.

The main differences between the dwarf and the terrestrial group of planets

The difference between these planets and the Earth 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 clear the path in front of them in their orbit with their mass. Unlike large ones, these planets, as a rule, cross in 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:

1. Pluto(the well-known planet, which at the meeting of the ISO in 2006, was reclassified from a planet to a dwarf one).
2. Ceres is a dwarf planet between Mars and Jupiter in the asteroid belt.
3. Makemake- little studied, the third largest dwarf planet in the solar system.
4. Haumea- unusual for very fast rotation around its axis.
5. Eris- in terms of mass, it is the second dwarf planet after Pluto, although it is possible that the first data is being specified.

However, according to some scientists, it may contain about 100 or more small dwarf planets they just haven't been discovered yet.

The International Astronomical Union has designated the planets beyond Neptune as "Plutoids".

So it is believed that Eris, which revolves around the Sun far beyond the orbit of Neptune, becomes plutoidhome, 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 the 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 the Earth	1.305 10 22 0,0022
	Mean equatorial radius in km	0,180 1148,07
	First escape 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 the Earth	?
	Mean equatorial radius in km	?
	First escape velocity (km/s)	?
	Rotation period (days)	0.32
	Number of known satellites	1
	opening date	31.03.2005
Eris	Location	Scattered disk
	Dimensions (km)	2326±12
	Weight in kg. Relative to the Earth	~1.67 1022 0,0028
	Mean equatorial radius in km	0,19 ~1300
	First escape 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 the Earth	4.2 1021 0,0007
	Mean equatorial radius in km	~750
	First escape 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 the Earth	8.3 1020-7.0 1021
	Mean equatorial radius in km	?
	First escape velocity (km/s)	?
	Rotation period (days)	0.42 d (10 h)
	Number of known satellites	0
	opening date	14.11.2003

Other dwarf planet candidates

Thanks to modern detection tools, scientists have discovered several dozen large cosmic bodies that can be attributed and qualified as 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.

Possible contenders for the status of a dwarf planet

Name	Category	Diameter	Weight
2015 KH162	Cubiwano in the Kuiper Belt	400-800 km	unknown
2007 OR 10	Scattered disk object	~1535 km	unknown
Quaoar	Cubiwano in the Kuiper Belt	1074-1170 km	1.0-2.6 10 21 kg
2002 MS 4	Cubiwano in the Kuiper Belt	~934 km	unknown
Orc	Plutino in the Kuiper Belt	917-946 km	6.2-7.0 10 20 kg
salacia	Cubiwano in the Kuiper Belt	~921 km	4.5 10 20
2013 FY27	Scattered disk object	~733 km	unknown
Varuna	Cubiwano in the Kuiper Belt	722 km	~5.9 10 20 kg
2002 UX 25	Cubiwano in the Kuiper Belt	681-910 km	~7.9 10 20 kg
Ixion	Plutino in the Kuiper Belt	~650 km	5.8 10 20
2002AW197	Cubiwano in the Kuiper Belt	626-850 km	~4.1 10 20 kg
2005 UQ 513	Cubiwano in the Kuiper Belt	550-1240 km	unknown
Varda	Cubiwano in the Kuiper Belt	500-1130 km	~6.1 10 20 kg
2005 R.N.43	Cubiwano in the Kuiper Belt	~730 km	unknown
2003 V.S. 2	Plutino in the Kuiper Belt	~725 km	unknown
2007JJ43	unknown(Kuiper Belt)	609-730 km	unknown
2004 GV9	Cubiwano in the Kuiper Belt	~677 km	unknown
2002 TC 302	Scattered disk object	590-1145 km	1.5 10 21
2003-AZ-84	Plutino in the Kuiper Belt	573-727 km	unknown
2004XA192	Cubiwano in the Kuiper Belt	420-940 km	unknown
2010 RE64	Cubiwano in the Kuiper Belt	380-860 km	unknown
2010 RF43	Cubiwano in the Kuiper Belt	~613 km	unknown
Chaos	Cubiwano in the Kuiper Belt	~600 km	unknown
2007 UK 126	Scattered disk object	~600 km	unknown
2003 UZ 413	Cubiwano in the Kuiper Belt	~591 km	unknown
2006 QH181	Scattered disk object	460-1030 km	unknown
2010 EK 139	Scattered disk object	470-1000 km	unknown
2010KZ39	Scattered disk object	440-980 km	unknown
2001 UR 163	Scattered disk object	~636 km	unknown
2010 FX86	Scattered disk object	~598 km	unknown
2013 FZ27	Scattered disk object	~595 km	unknown
2012 VP 113	Scattered disk object	~595 km	unknown
2008 ST 291	Scattered disk object	~583 km	unknown
2005 RM43	Scattered disk object	~580 km	unknown
1996 TL66	Scattered disk object	~575 km	2 10 20
2004 XR 190 "Buffy"	Scattered disk object	425-850 km	0.6-4.8 10 20
2004NT33	Cubiwano in the Kuiper Belt	423-580 km	unknown
2004 U.M. 33	Cubiwano in the Kuiper Belt	340-770 km	unknown
2002XW93	Scattered disk object	565-584 km	unknown
2004 TY 364	Cubiwano in the Kuiper Belt	~554 km	unknown
2002XV93	Plutino in the Kuiper Belt	~549 km	unknown

Municipal educational institution

Vnukovo secondary school

Conference

"Project of the Year"

dwarf planets

solar system

Project work around the world

Completed:

student 4 "B" class

Zavyalov Vasily

Supervisor:

Dmitrov

2014

Purpose of work .. 3

Introduction. 4

dwarf planet. 6

Examples of dwarf planets. 6

Planet Ceres. 6

Planet Pluto. 7

Planet Haumea. eight

Planet Makemake. 8

Planet Eris. nine

comparison table. 10

Conclusion . 12

Bibliography.. 13

Appendix . fourteen

Objective

1. Get acquainted with new studies of the planets of the solar system.

2. Find out if there are changes in the solar system as a result of the latest astronomical discoveries.

Hypothesis:With the help of modern powerful telescopes and the research work of astronomical observatories, new cosmic bodies in our solar system can be discovered and the classification of the planets will change.

Introduction

The term "dwarf planet" was adopted in2006 within the framework of the classification of bodies revolving around the Sun into three categories. Bodies large enough to clear the vicinity of their orbit are defined as planets , but not large enough to achieve even hydrostatic equilibrium - as small solar system body or asteroids. Dwarf planets are intermediate between these two categories. This definition has 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.

What celestial body is called a planet

A planet is a celestial body in orbit around a star or its remnants, massive enough to become rounded under the influence of its own gravity, but not massive enough to start a thermonuclear reaction, and has managed to clean up the vicinity of its orbit.

Fig.1. Planet Earth

dwarf planet

Bodies large enough to clear the vicinity of their orbit are defined asplanets , but not large enough to achieve even hydrostatic equilibrium - as small bodies of the solar system or asteroids. Dwarf planets are intermediate between these two categories. This definition has met with both approval and criticism, and is still disputed by some scientists.

Fig.2. dwarf planet

Examples of dwarf planets

Planet Ceres

Ceres- a dwarf planet in the asteroid belt inside the solar system. Ceres is the closest dwarf planet to Earth (the average distance between orbits is about 263 million km). Ceres was discovered on the evening of January 1, 1801 by the Italian astronomer Giuseppe Piazzi at the Palermo Astronomical Observatory. For some time, Ceres was considered as a full-fledged planet in the solar system; in 1802, it was classified as an asteroid, and according to the results of clarifying the concept of "planet" by the International Astronomical Union on August 24, 2006, at the XXVI General Assembly of the IAU, it was classified as a dwarf planet. It was named after the ancient Roman goddess of fertility, Ceres.

Fig.3. Planet Ceres

Planet Pluto

Pluto- the largest along withEridoi is a dwarf planet in the solar system, a trans-Neptunian object and the tenth largest (excluding satellites) celestial body circling around sun . Pluto was originally classified as a classical planet , however, it is now considered a dwarf planet and one of the largest objects (perhaps the largest) in the Kuiper belt.Pluto lost its status as a planet and was demoted to a "dwarf planet". There are now only eight large planets in the solar system and many dwarf ones.

Fig.4. Planet Pluto

Planet Haumea.

Haumea, or haumea- fourth largestdwarf planet solar system . classified as plutoid, trans-Neptunian object . This is the fastest rotating body of all the studied objects in the solar system, with a diameter of more than 100 km. Haumea has a strongly elongated shape. She has 2 satellites.

Fig.5. Planet Haumea

Planet Makemake

Makemake- third largestdwarf planet of the solar system. Refers to trans-Neptunian objects, plutoids . It is the largest known classical Kuiper belt objects.

Fig.6. Planet Makemake

Planet Eris

Eris- the largest ofdwarf planets solar system . Formerly known as Xena. Refers to trans-Neptunian objects, plutoids. Before the XXVI Assembly of the International Astronomical Union Eris claimed tenth status planets . However, on August 24, 2006 International Astronomical Union approved the definition of a classical planet, to which Eris, like Pluto , does not match. Thus, although Pluto's status as a planet has long been disputed due to the discovery of other trans-Neptunian objects, it was the discovery of Eris that spurred the process of revising it instead of recognizing Eris as a planet. Eris has long been considered significantly larger than Pluto, but, according to recent data, their sizes are so close that it is impossible to say with certainty which of these objects is larger.

Fig.7. Planet Eris

comparison table

Fig.8. Planet Comparison

Similarities and differences between a classical planet and a dwarf planet.

Table 1. Comparison of planets

CLASSIC PLANET	dwarf planet
1.revolves around the sun	1.revolves around the sun
	2. has sufficient mass so that self-gravity exceeds solid forces and the body can take a hydrostatically equilibrium (close to spherical) shape
3.revolves around the sun	3.revolves around the sun
4. clears the vicinity of its orbit (i.e., there are no other bodies comparable to the planet near the planet), therefore it rotates in one direction around the Sun	4. does not clear the vicinity of its orbit, therefore it changes the direction of rotation

Conclusion

Now, according to the new classification, the solar system will have four terrestrial planets (Mercury, Venus, Earth and Mars), the same number of giant planets (Jupiter, Saturn, Neptune and Uranus) and an unlimited number of dwarf planets. Russian scientists are against the withdrawal of Pluto from a number of planets in the solar system. Therefore, a few more years of research, we will wait for changes.

There are now only 5 dwarf planets - Ceres, Pluto, Haumea, Makemake and Eris. But this is only the beginning. Another 40 cosmic bodies are waiting for the time when they will also be given the status of dwarf planets.

Bibliography

1. Avanta+, Encyclopedia for children. Volume 8. Astronomy - Avanta+, 2004. - 688 p. - ISBN-040-1

2. , White spots of the solar system - M .: Niola-Press, 2008. - 319 p. - ISBN 0363-6

3. And, I know the world. Space. - M.: AST, Keeper, 2008. - 398 p. - ISBN-8, 2900-7.

4. , Migration of celestial bodies in the solar system. - Editorial URSS. - 2000. - ISBN -

5. , Astronomy: Proc. for 11 cells. general education institutions/- 9th ed. - M.: Education, 2004. - 224 p.: ill. - ISBN-0.

6. , Sky of the Earth - L .: Children's literature, 1974. - 328 p.

7. http://ru. wikipedia. org/wiki

font-size:18.0pt;line-height:107%;font-family:" times new roman color:windowtext>app

Fig.9. Solar system (my drawing)

Of course, these are just figurative comparisons. In reality, there are giant planets and dwarf planets.

giant planets

These are the planets known to us, which we have already talked about more than once on our website: Jupiter, Saturn, Uranus, Neptune. All of them are located outside the ring of minor planets (asteroids). According to their physical characteristics, they are very similar, so they are combined into one group - outer planets, or gas giants. What are these physical characteristics? Significantly larger sizes and masses (as a result of this, the pressure in their depths is much higher), lower average density (close to the average Solar, 1.4 g/cm³), powerful atmospheres, rapid rotation, and rings (while there are no terrestrial planets) and more satellites.
Why are these giant planets called gas? Because they are mostly composed of gas (mainly hydrogen and helium). Scientists believe that the gas giant planets formed earlier than the terrestrial planets. When most of the refractory substances (oxides, silicates, metals) fell out of the gas phase, the inner planets (from Mercury to Mars) formed from them.
The period of rotation of gas planets around its axis is only 9–17 hours.

The picture shows the gas giant planets in comparison with the Sun.

Presumably, gas giants have a small stone or metal core, and the pressure in their atmosphere is so high that hydrogen turns into a liquid state. And if the planet is especially large, then below this layer of liquid hydrogen there may be another layer of metallic hydrogen (like liquid metal). Scientists have also found that all gaseous planets radiate more heat than they receive from the Sun. This can be explained by the fact that either the planets are gradually shrinking, or thermonuclear reactions are taking place in them. thermonuclear reaction- a kind of nuclear reaction in which light atomic nuclei are combined into heavier ones due to the kinetic energy of their thermal motion.
In the atmospheres of gas planets, powerful winds blow at speeds of up to thousands of kilometers per hour, and atmospheric formations form giant whirlwinds there. For example, the Great Red Spot several times the size of the Earth on Jupiter has been observed for more than 300 years. There is a Great Dark Spot on Neptune, smaller spots on Saturn.
Only large planets can be gas, since small celestial bodies are not able to hold such a light gas as hydrogen.
Everything that we have said here about the gas giant planets refers to the group of outer planets of the solar system. But gas giant planets also exist outside the solar system. The largest known gas planet is TrES-4b.

Planet TrES-4b

This is a gas giant, one of the largest known planets, which is 70% larger than Jupiter. In the picture, Jupiter and TrES-4b are shown in comparison. This planet is in the constellation Hercules and orbits the star GSC02620-00648. It is 1435 light years away from Earth. To make it clear how huge this distance is, let's explain what a light year is. Light year(St. g., ly) is an off-system unit of length equal to the distance traveled by light in one year. And if we take into account that 1 light second ≈ 299,792.5 km, then we can calculate the distance to the planet TrES-4b. Interestingly, this planet was discovered by amateur astronomers.

dwarf planets

The characteristic of this type of planets was given by the International Astronomical Union. Dwarf planets should not be confused with the minor planets of the solar system, or asteroids.
So, according to the classification of the International Astronomical Union adopted in 2006, dwarf planets is a celestial body that:
orbits around the sun;
has sufficient mass to maintain hydrostatic balance under the action of gravitational forces and have a shape close to rounded;
is not a satellite of the planet;
does not dominate its orbit (cannot clear space from other objects).
Bodies large enough to clear the vicinity of their orbit are considered planets, but not large enough - small bodies of the solar system, or asteroids. dwarf planets occupy an intermediate position between these two categories. Not all astronomers agree with this classification, but so far it is.
Five dwarf planets are officially recognized: Ceres, Pluto, Haumea, Makemake, Eris. Interestingly, from this list, only Pluto was “downgraded”, becoming a dwarf planet and losing the status of a planet, while the rest, on the contrary, were “upgraded”, ceasing to be just one of the asteroids.
It is possible that at least 40 other 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 outside it. All of this is within the solar system. The Kuiper belt is the region of the solar system from the orbit of Neptune to a distance of about 55 AU. e. from the Sun.
The classification of bodies with characteristics of dwarf planets in other planetary systems has not yet been determined.

Ceres

Ceres is the closest dwarf planet to the Earth, it is 263 million km away from the Earth. It was discovered in 1801 by the Italian astronomer Giuseppe Piazzi at the Palermo Astronomical Observatory. With a diameter of about 950 km, Ceres is by far the largest and most massive body in the asteroid belt. Recent observations have shown that it has a spherical shape, unlike most small bodies, which have an irregular shape due to low gravity. The surface of Ceres is likely a mixture of water ice and various minerals such as carbonates and clays. Ceres is hypothesized to have a rocky core and an icy mantle, and may even contain, in places, oceans of liquid water below its surface. The mass of Ceres is 9.5 1020 kg, the period of revolution is 4.599 years. The average surface temperature is 167K.

Structure of Ceres:
1 - thin layer of regolith;
2 - ice mantle;
3 - stone core.

From Earth, the apparent brightness of Ceres ranges from magnitude 6.7 to magnitude 9.3, making it impossible to see with the naked eye. On September 27, 2007, NASA launched the Dawn probe to study Vesta (2011-2012) and Ceres (2015). Ceres has no moons yet.

Pluto

The largest dwarf planet in the solar system along with Eris in size and the tenth largest (excluding satellites) celestial body orbiting the Sun. Pluto was originally classified as a planet, but is now considered one of the largest objects (perhaps the largest) in the Kuiper Belt. Like most objects in the Kuiper belt, Pluto is made up mostly of rock and ice.
Pluto was discovered back in the 19th century, but it was given a name only in 1930 - this date is considered the date of its discovery. It was considered the ninth planet in the solar system until 2006, but then objects in the outer solar system, such as Eris, were discovered that were more massive than Pluto, and the International Astronomical Union ranked it in a new category of dwarf planets, along with Eris and Ceres.

Pluto's orbit is strongly inclined (17º), the average distance of Pluto from the Sun is 5.913 billion km. Pluto is in a 3:2 orbital resonance with Neptune - for every three revolutions of Neptune around the Sun, there are two revolutions of Pluto, the whole cycle takes 500 years. orbital resonance is a situation in which two (or more) celestial bodies have periods of revolution that are related as small natural numbers. As a result, these celestial bodies exert a regular gravitational influence on each other, which can stabilize their orbits. If Pluto was not initially in resonance with Neptune, then it probably approached it much more strongly from time to time, and these approaches over billions of years affected Pluto, changing its orbit and turning it into the one we observe today. The calculations made it possible to establish that over millions of years the general nature of the interactions between Neptune and Pluto does not change.
Among the objects of the solar system, Pluto is smaller in size and mass, not only in comparison with other planets, it is inferior even to some of their satellites. Pluto's atmosphere is a thin shell of nitrogen, methane, and carbon monoxide evaporating from surface ice. Recently it was calculated that the temperature on the surface of Pluto is 43 K.
Five natural satellites of Pluto are known, three of them have names today: Charon, discovered in 1978 by astronomer James Christie, and two small satellites, Nix and Hydra, discovered in 2005. The fourth satellite was discovered using the Hubble telescope; the announcement of the discovery was published on July 20, 2011 on the telescope's website. Temporarily named S/2011 P 1 (P4); its dimensions range from 13 to 34 km. On July 11, 2012, the discovery of the fifth moon of Pluto was announced.

It is the fourth largest dwarf planet in the solar system, located in the Kuiper Belt, its diameter is more than 100 km. Haumea has a strongly elongated shape. She has 2 satellites. Haumea was discovered independently by an American and Spanish team of astronomers in 2004. Haumea is an unusual planet. It rotates very quickly - its period of revolution around its own axis is 3.9155 hours. Very fast rotation distorts its shape.
In 2005, a study of the Haumea spectrum was carried out using telescopes at the Gemini and Keck observatories. As a result, it was found that its surface is covered mainly with water ice in the form of grains with a diameter of 25 or 50 microns. Haumea has two satellites. Its mass is 4.2 1021 kg, the average surface temperature is unknown.

Makemake is the third largest dwarf planet in the solar system. Refers to trans-Neptunian objects, plutoids. It is the largest known classical Kuiper belt object. Makemake was discovered by a group of American astronomers in 2005. As of 2012, Makemake is located 7.8 billion km from the Sun. This is a fairly bright object, it can be photographed through a powerful amateur telescope. The size and mass of Makemake are not exactly known. The circulation period is 248.09 years. The average surface temperature is also not known.
During the study of Makemake by the Spitzer and Herschel space telescopes, it was found that the surface of Makemake is inhomogeneous. While most of the surface is covered in methane snow, there are small patches of darkened terrain. The researchers found that its surface is similar in chemical composition to the surface of Pluto. No satellites have been found in orbit around Makemake.

The most massive of the dwarf planets in the solar system, located in the Scattered Disk. Formerly known as Xena. Eris has long been considered significantly larger than Pluto, but, according to recent data, their sizes are so close that it is impossible to say with certainty which of these objects is larger. Eris was discovered by a group of American astronomers in 2005. The average distance of Eris from the Sun is 10.18 billion km, but its orbit is highly elongated. It is impossible to directly observe the planet in an amateur telescope. It is very difficult to accurately determine the size of such a distant celestial body. Measurements of the size of Eris, carried out in 2007 using the Spitzer infrared space telescope, made it possible to estimate its diameter at ~ 2600 + 400 km. The question of which of the dwarf planets - Pluto or Eris - is actually the largest in the solar system remains open. The mass of Eris is determined due to the presence of a satellite, it is greater than the mass of Pluto and is equal to 1.67 1022 kg. According to a photometric study conducted in 2006, Eris makes a full rotation around its axis in at least 5 Earth days. Spectroscopic observations in 2005 at the Gemini Observatory showed the presence of methane snow on the surface of Eris, which is similar to Pluto and Neptune's moon Triton. Eris differs from Pluto and Triton in color. Pluto and Triton are reddish, and she is greyish. This is due to the presence of ethane and ethylene ice on Eris. Eris has 1 known moon. The orbital period is 557 years, the average surface temperature is 30K.

Review of dwarf planets: Pluto, Eris, Makemake, Haumea, Ceres

Our solar system is under the constant attention of not only astronomers, but also just those who like to keep abreast of space events and news. And if such cosmic bodies as Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune are always in the public eye and everyone knows about them, then the dwarf planets have become the object of general attention quite recently.

Pluto

Once a planet, Pluto lost it in 2006, when the International Astronomical Union first defined the term "planet". At the moment, it is considered the largest dwarf planet in the solar system. However, the head of the New Horizons mission, Alan Stern, under whose careful supervision the probe made a successful flyby over the surface of Pluto, recently made a very impressive statement. He said that Pluto is a planet.

In support of his statement, he cited two facts. First, he pointed out that Pluto's shape is in full accordance with the mass, and secondly, he pointed out that this world is incredibly active, it has hydrocarbon rains and seismic activity and nitrogen glaciers. The scientist believes that this cosmic body cannot be considered just an immovable object, the surface of which is covered with rocks and ice. It is very likely that, according to his arguments, the status of Pluto can be changed in the near future.

His words were confirmed by the latest pictures taken by the Lorrie camera of the New Horizons spacecraft, which indicated that the heart-shaped plain on Pluto has huge deposits of ice in the very center that are in constant dynamics. This indicates the complex geological structure of the dwarf planet. It turned out that the movement of glaciers on the surface is carried out in the same way as on Earth. Recent studies indicate that the chemical composition of this glacier includes nitrogen, methane and carbon dioxide.

But Pluto is far from the only dwarf planet in our solar system discovered to date. We offer you to get acquainted with the less known, but no less interesting dwarf worlds known today.

Eris

The dwarf planet Eris is to some extent responsible for Pluto's "downgrade" to a dwarf planet in 2006. It is a small world that moves in a strange elliptical path around the Sun and was discovered by astronomer Mike Brown in 2003.

When Eris was first discovered, scientists thought it might actually be even bigger than Pluto. Such conclusions caused controversy among astronomers who wanted the classification of cosmic bodies in the solar system to be revised, which happened. But, it turned out that its size is smaller and now Eridu has the status of the second largest dwarf planet in the solar system.

Because Eris is so far from the Earth and from the Sun (10.18 billion km), makes it a difficult planet to study. So there were difficulties with determining its size. The reason for this is the strong brightness of Eris, due to which its albedo can be overestimated. Taking into account the absolute stellar magnitude of the cosmic body, its diameter should be at least 2300 km.

Makemake

Discovered in 2005, the dwarf planet Makemake lies in the Kuiper Belt. This tiny world takes 310 Earth years to complete one revolution around the Sun.

Scientists believe that the dwarf planet actually has a reddish-brown hue. And at first glance, this is the dominant color in this part of the space. However, data from the New Horizons probe has confirmed that Pluto has a reddish hue, and other objects in the Kuiper belt also have a predominantly red tint.

According to NASA officials, signs of frozen nitrogen have been found on the surface of this dwarf planet. In addition, the chemical composition of the cosmic body includes frozen ethane and methane. According to scientists, methane is present on the surface in the form of granules, the diameter of which is at least one centimeter.

Haumea

Haumea moves very fast. The dwarf planet rotates at such a speed that it completes a complete revolution on its axis every four hours. Scientists believe that the rotation gave an elongated shape to this planet. A dwarf planet - discovered in 2003 - also in the Kuiper belt, it makes a complete revolution around the Sun every 285 Earth years, and its size is not much smaller than the size of Pluto.

Astronomers believe that the surface of Haumea is covered with rocks with an ice crust. Haumea is named after the Hawaiian goddess of fertility.

Ceres

The dwarf planet Ceres is actually a strange and mysterious cosmic body. The small, cratered world doesn't belong to the Kuiper belt, but that doesn't stop it from orbiting the sun.

Ceres was discovered in 1801. However, detailed information about it was obtained thanks to data received from the NASA spacecraft Dawn, which has been studying the small world since March 2015. The probe found a number of craters with bright spots inside them. Scientists, representatives of the mission, at the moment can not yet give accurate information about the composition of these light-reflecting areas. Getting more accurate data will allow the launch of the Rassvet spacecraft into a lower orbit of Ceres.

“We are now comparing the spot with the reflective properties of salt, but there is no concrete result yet,” said Chris Russell, principal investigator of the mission, about the nature of the spots. "We look forward to new data and high-resolution photographs after the next orbital phase of the mission."

And the rest...

NASA scientists believe that there may be up to several dozen dwarf planets orbiting the Sun.

They pin certain hopes on the New Horizons probe, which is capable of exploring another large area of ​​space. Perhaps in four or five years, he will be able to detect one or more objects in the Kuiper belt. At the moment, there is a question about funding the mission, but if it receives support from NASA, then perhaps humanity will be able to see more than one new dwarf world in our solar system.

Translation: Unvalennaya T.

Editing: Kolupaev D.