– celestial bodies of the Solar System: characteristics, features, history of Pluto, definition, requirements for planets, list and candidates.

Term dwarf planet officially appeared in 2006, when planets the size of Pluto and larger were found beyond the orbit of Neptune. Since then, many bodies in the Solar System have been called dwarf planets.

In addition, the concept has caused much controversy, especially regarding the status and nature of Pluto. The IAU now recognizes the existence of 5 dwarf planets, and approximately two hundred are awaiting confirmation. Let's see what the characteristics of dwarf planets look like.

Definition of dwarf planets

Dwarf planet called a celestial object that:

• revolves around the Sun;
• has enough mass to become almost round;
• but cannot clear its orbital path.

In short, this is the name given to any object with planetary massiveness, but not protruding as a planet or moon. But the body must revolve around the Sun and have a spherical shape. Below is a list of dwarf planets, which includes their features, descriptions and photos.

Potential dwarf planets:

Size and mass of dwarf planets

For a body to acquire a rounded shape, it must have enough mass to resist its own gravity. The internal pressure then forms the surface layer, ensuring plasticity that fills the raised areas and depressions. This doesn't happen with asteroids.

For celestial bodies with a diameter of a couple of kilometers, the most significant force is gravity, so they stretch out like potatoes. The larger the object, the higher the level of internal pressure until it reaches a point of internal balance. Admire the table of the main characteristics of dwarf planets, which includes a description of the orbit.

But the appearance of small solar system bodies can also be affected by axial rotation. If it is not there, then we get a sphere. The higher the speed, the more noticeable the level of flattening. As a result, the object goes to extremes, like Haumea, which is twice as long along the main axis. Tidal forces close objects, forcing them to show only one side. This is seen in the Pluto-Charon connection.

The IAU has not provided an upper or lower bound on the mass of dwarf planets. But the lower one is displayed as a point that allows achieving hydrostatic balance. Size and mass are based on composition and thermal history.

For example, silicate asteroids reach balance at a diameter of 600 km and a mass of 3.4 x 10 20 kg. If there is less hard water ice in the object, then the limit will be 320 km and 10 19 kg. It turns out that there is no standard for size or weight. Therefore, the basis for now is the form.

Orbital dominance of dwarf planets

Many scientists insisted that hydrostatic balance be added to the ability to cleanse the space around oneself. In general, this is the ability of planets to eliminate smaller bodies next to them, attracting or repelling them. Dwarfs simply do not have enough mass.

To determine this, Alan Stern and Harold Levison introduced the lambda parameter. Scientists like Stephen Sauter use it to separate dwarf planets from ordinary ones. He also put forward a parameter - the planetary discriminant (μ), determined by dividing the mass of a body by the mass of other objects with which it shares an orbit.

Dwarf planets and candidates

The list of dwarf planets in the solar system includes Pluto, Makemake, Eris, Haumea and Ceres. Only the first and last ones do not cause controversy. The IAU determined that among trans-Neptunian objects (TNOs), only those with a diameter of 838 km and brighter than 1 become dwarf. The bottom diagram shows a comparison of the sizes of dwarf planets.

Among the contenders: Orcus, 2002 MS4, Actea, Quaoar, 2007 OR10 and Sedna. They all live in the Kuiper Belt or Scattered Disk. Sedna stands out and stands in a class of its own. It is believed that there may be another 40 known objects that should be classified as dwarf planets. But there are more than two hundred more in the Kuiper belt, and the total number can exceed 1000.

Dwarf planet controversy

When the IAU adopted new criteria, many scientists disagreed and a dispute ensued. Mike Brown (who discovered Eris) agreed with the new rules and reducing the official number of planets to 8. But Alan Stern made serious criticism.

He said that Mars, Jupiter, Neptune and Earth also did not completely clear the space around them. With our planet, another 10,000 near-Earth asteroids revolve around the Sun, and Jupiter has 100,000 Trojans. Therefore, Stern stubbornly considered Pluto a planet, and Ceres and Eris as additional ones.

Problems also arise for the classification of exoplanets. We can identify characteristics only indirectly, so we do not know whether the orbit has cleared. Because of this, criteria emerged regarding minimum mass and size.

Municipal educational institution

Vnukovo secondary school

Conference

"Project of the Year"

Dwarf planets

solar system

Project work on the surrounding world

Completed:

student of 4th grade "B"

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. 8

Planet Makemake. 8

Planet Eris. 9

comparison table. 10

Conclusion . 12

Bibliography.. 13

Application . 14

Goal of the work

1. Get acquainted with new research on the planets of the solar system.

2. Find out whether 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 can be discovered in our Solar System and the classification of planets can change.

Introduction

The term "dwarf planet" was adopted in2006 within the framework 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 , but not large enough to achieve even hydrostatic equilibrium - as small solar system body or asteroids. Dwarf planets occupy an intermediate position 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 larger, then a planet, if smaller, a planetoid.

What celestial bodies are called planets

A planet is a celestial body orbiting a star or its remnant that is massive enough to become rounded by its own gravity, but not massive enough to initiate a thermonuclear reaction, and has managed to clear 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 occupy an intermediate position 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 within the solar system. Ceres is the dwarf planet closest 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 based on 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 withEris is the size of a dwarf planet in the Solar System, a trans-Neptunian object and the tenth most massive (excluding satellites) celestial body revolving around Sun . Pluto was originally classified as a classical planet , however, it is now considered a dwarf planet and one of the largest objects (possibly the largest) in Kuiper belt.Pluto lost its planetary status and was demoted to "dwarf planets". There are now only eight large planets and many dwarf planets in the solar system.

Fig.4. Planet Pluto

Planet Haumea.

Haumea, or Haumea- fourth largestdwarf planet of the 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 highly elongated shape. She has 2 satellites discovered.

Fig.5. Planet Haumea

Planet Makemake

Fig.6. Planet Makemake

Planet Eris

Eris- the most massive ofdwarf planets of the solar system . Previously known as Xena. Refers to trans-Neptunian objects, plutoids. Until the XXVI Assembly of the International Astronomical Union Eris claimed the status of the tenth planets . However, on August 24, 2006 International Astronomical Union approved the definition of a classical planet, which Eris, like Pluto , does not match. Thus, although Pluto's status as a planet had long been disputed due to the discovery of other trans-Neptunian objects, it was the discovery of Eris that prompted the process of its revision instead of recognizing Eris as a planet. Eris has long been considered significantly larger than Pluto, but, according to the latest 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. Comparison of planets

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

Table 1. Comparison of planets

Conclusion

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

There are now only 5 dwarf planets - Ceres, Pluto, Haumea, Makemake and Eris. But this is just 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, Guardian, 2008. - 398 p. - ISBN -8, 2900-7.

4. , Migration of celestial bodies in the Solar System. - Editorial URSS. - 2000. - ISBN -

5. , Astronomy: Textbook. for 11th grade 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>Appendix

Fig.9. Solar system (my drawing)

Dwarf planets Pluto, Haumea, Makemake, Eris and other large trans-Neptunian objects compared by size, albedo and color. Their satellites are also shown.

A dwarf planet, as defined by the International Astronomical Union, is a celestial body that:

orbits around ;
has sufficient mass to maintain hydrostatic equilibrium under the influence of gravity and have a close to spherical shape;
is not ;
cannot clear the area of ​​its orbit from other objects.

The term "dwarf planet" was adopted in 2006 as part of the classification of bodies orbiting the Sun and other bodies into three categories. Bodies large enough to clear space in the band of their orbit are defined as planets, and bodies not large enough to achieve even hydrostatic equilibrium are defined as or. Dwarf planets occupy an intermediate position 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 by size, or even: if larger, then it’s a planet, if smaller, then it’s a planetoid.

The International Astronomical Union officially recognizes 5 dwarf planets: the largest asteroid and -,; however, it is possible that at least 40 more of the known objects in the world belong to this category. According to various estimates by scientists, up to 200 dwarf planets can be discovered in and up to 2000 dwarf planets beyond.

The classification of bodies with the characteristics of dwarf planets in other planetary systems has not been determined.

List of dwarf planets

In 2006, the IAU officially named three bodies that were immediately classified as dwarf planets - the former planet Pluto, considered the largest trans-Neptunian object, Eris and the largest asteroid Ceres. Later, two more trans-Neptunian objects were declared dwarf planets. The term "dwarf planet" should be distinguished from the concept of "minor planet", which historically also referred to asteroids.

*Value in comparison with Earth.

From this list, only Pluto was “demoted”, becoming a dwarf planet and losing its status as a planet, and the rest, on the contrary, were “promoted”, ceasing to be just one of the asteroids.

Other candidates

Several dozen bodies are already known that could potentially qualify as dwarf planets.

The status of Charon, which is now considered to be a satellite of Pluto, remains inconclusive, since there is currently no precise definition for distinguishing planets with a satellite from binary planetary systems. The draft resolution published by the IAU indicates that Charon can be considered a planet because:

Charon itself meets the size and shape criteria for planetary status (in terms of the latest resolution, for dwarf planet status).

The status of Charon, which is now considered to be a satellite of Pluto, remains inconclusive, since there is currently no precise definition for distinguishing planets with a satellite from binary planetary systems. Draft Resolution (5) published by the IAU indicates that Charon can be considered a planet because:

1. Charon itself meets the size and shape criteria for dwarf planet status.
2. Charon, due to its large mass compared to Pluto, orbits Pluto around a common center of mass located in space between Pluto and Charon, rather than around a point inside Pluto.

This definition, however, is not included in the final decision of the IAC. It is also unknown whether it will appear in the future. If such a definition is approved, Charon will be considered a dwarf (double) planet. To quickly resolve this issue, we are currently discussing the adoption of tidal interlocking or synchronous rotation of both components of the binary system as an additional criterion.

Besides Charon and all other candidate trans-Neptunian objects, three large objects in the asteroid belt (Vesta, Pallas and Hygeia) would have to be classified as dwarf planets if their shape is found to be determined by hydrostatic equilibrium. To date, this has not been convincingly proven.

Size and mass of dwarf planets

The lower and upper limits for the size and mass of dwarf planets are not specified in the IAU decision. There are no strict restrictions on the upper limits, and an object larger or more massive than Mercury with an unrefined orbital neighborhood 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 the object that has achieved this shape is unknown. Empirical observations suggest that they may vary greatly depending on the composition and history of the object. The original IAU preliminary decision defining hydrostatic equilibrium applied to “objects with a mass greater than 5 x 1020 kg and a diameter greater 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.

Our solar system is rich in many interesting phenomena. Dwarf planets deserve special attention. They are objects orbiting the sun, with some similarities to asteroids.

Dwarf planets of our solar system

Our solar system is rich in many interesting phenomena. Among them deserve the greatest attention. All of them are objects orbiting the Sun, with some similarities to asteroids. In this article we will look at what it is in general terms. Then we’ll take a closer look at the dwarf planet Sedna.

Main characteristics of objects

In relation to dwarf planets, there are requirements from the International Astronomical Union. Objects must strictly comply with them. Otherwise, they cannot be called dwarf planets, but must have a different name. So, the objects in question meet the following requirements:

• have a weight that allows them to maintain hydrostatic equilibrium and have a spherical appearance;


• are not able to clear the surroundings of their own orbit from other space objects;


• revolve around the Sun;


• should not be satellites of other planets.

Today, only six dwarf planets are known. These include Sedna, Eris, Makemake, Haumea, Pluto and Ceres. Each of the listed objects differs from the other as much as the “large” planets differ from each other.

It was possible to study only two of the six “dwarfs”. One of NASA's interplanetary stations is still in orbit of one dwarf planet - Ceres. High-quality images of the surface of the celestial body were obtained. Photos taken by AMC Dawn Station. This is an advanced spacecraft. Its engines operate on ion thrust. Therefore, with the help of AMC Dawn, it became possible to study several space objects at once.

It was this device that for the first time in history entered the orbit of an asteroid and collected all the necessary information about it. After which he retired to explore the next celestial body - the dwarf planet Ceres. The use of this automatic station made it possible to make a breakthrough in the study of the main asteroid belt. AMC Dawn has created an accurate and detailed map of the surface of asteroids and dwarf planets.

Two years ago, the New Horizons spacecraft made its first close approach to the largest of the six objects, Pluto. As a result, photographs of its surface were also obtained. The appearance of the remaining dwarf planets is currently unknown to humanity.

The list of objects under consideration may be expanded. Astronomers have about forty candidates for the title of “dwarf planet.” All of them are located outside of Neptune. But there is no clear data about these objects. Therefore, they are not yet officially classified as dwarf planets. There is also an opinion that at least two thousand objects of this type are located in the Kuiper belt, the Oort cloud and the scattered disk.

It is safe to say that extrasolar dwarf planets also exist. But nowadays they are unlikely to be open. Modern telescopes do not provide this opportunity. But science does not stand still. Perhaps in the near future we will learn a lot of interesting things.

Sedna: what do astronomers know?

There is a popular theory according to which the Sun, through its gravity, stole several hundred dwarf planets and asteroids from another star flying nearby. For the most part, this was all considered a wild guess. But these days there is already some confirmation of this hypothesis.

Astronomers have been attracted by the dwarf planet Sedna. It and several neighboring celestial objects move in rather strange orbits. In particular, Sedna is the most distant object in our Solar System. Moreover, the closest point of its orbit is located 76 AU from the star, and the farthest is located at 1007 AU. e. This object has a huge orbital period. It is eleven thousand four hundred and eighty-seven years. It is considered the longest among large celestial bodies.

Scientists tried to figure out the nature of this strange behavior of sednoids. They first tried to do this in 2003. That's when they were discovered. At first, scientists could not find a rational explanation. The theory was then put forward that the orbits of the sednoids were elongated by a passing star about four billion years ago.

Subsequently, computer modeling of the previously described hypothesis was carried out. This happened at the Leiden Observatory. It turned out that the star flying nearby did not affect the orbits of the sednoids. Rather, it was the Sun that attracted them to itself.

During the study, more than ten thousand variations of scenarios were taken into account, which took into account different combinations of distances, speed of passage and masses of stellar systems. The simulation was carried out under the guidance of famous astronomer Lucy Zhilkova.

The calculations carried out allowed us to calculate the most likely scenario. The star passing by was eighty percent larger than the Sun. The maximum convergence indicator was about thirty-four billion kilometers. In this case, the exchange of objects occurred on both sides. Some objects were added to the orbit of the Sun, while others, on the contrary, went to another system. This event apparently occurred about four billion years ago.

The work carried out by Zhilkova received good reviews and recognition from scientists around the world. However, we should not forget that this is just a theory, albeit a highly probable one. It still requires additional confirmation. This can be achieved by performing chemical analysis. If its results differ from data from trans-Neptunian objects, this will mean that the sednoids are of foreign origin. It is not possible to see the results of this analysis in the near future.

There is also a theory that claims the presence of an as yet undiscovered planet, whose orbit is located hundreds of AU. e. from the Sun. It is she who makes adjustments to Sedna’s flight path. Again, this is just a bold assumption that requires serious scientific study.

Results

There are many gaps in the study of dwarf planets. But with the development of new space exploration technologies, all of them will be quickly replenished. Modern scientific stations pay great attention to the study of this issue.

Definition of the concept of dwarf planets according to international standards

The International Astronomical Union (IAU) has defined space objects that will be called dwarfs. Thus, planets that have the following characteristics are considered dwarf:

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

The main differences between the dwarf and terrestrial 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 a path in front of themselves in their orbit with their mass. 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 been able to detect and classify five such objects:

1. Pluto(a well-known planet, which at the IOC meeting in 2006 was reclassified from a planet to a dwarf planet).
2. Ceres- 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 its very rapid 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 clarified.

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's orbit as "Plutoids".

So it is believed that Eris, which revolves around the Sun far beyond the orbit of Neptune, becomes plutoid, and Ceres from the Asteroid Belt becomes a dwarf planet.

Table of dwarf planets with astronomical characteristics

Other candidates for the title of dwarf planet

Thanks to modern detection means, scientists have discovered several dozen large cosmic bodies that can be classified as “Plutoid” planets. The table below shows planetoids with an approximate diameter of up to 600 km. Moreover, the first 6 objects will most likely become the main candidates.