Distance to the Kuiper Belt in a.e. Kuiper Belt and Oort Cloud

The Kuiper Belt is a disk-shaped region of icy objects beyond the orbit of Neptune - billions of kilometers from our Sun. The Kuiper Belt and even further out are believed to be home to comets orbiting the Sun.

In 1992, astronomer David Jewitt discovered the object 1992 QB1 outside the solar system. Over the next five years, he discovered another 40 to 50 similar objects. By mid-2016, the number of objects found was 2000. The region of discovered objects was called the “Kuiper Belt”. Scientists don't currently know where it ends. They don't know what's going on at the outer edge of the Kuiper Belt or where it is, but they do know that it's very far away: some discovered Kuiper Belt objects have unusual orbits that are 2,000 times greater than the distance between the Earth and the Sun. Despite the fact that there are a lot of Kuiper belt objects, scientists have discovered that their mass is quite small and is equal to only 10% of the mass of the Earth or 2/3 of the Moon. It was a mystery: how are these bodies formed if they have such a small mass? These bodies grow very slowly. Low-mass Kuiper Belt models have become a hot topic. They were based on the idea that the Kuiper belt was much more massive when it began to form - 20 or 40 times more massive than Earth. But most of the mass was lost.

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. More than 90% of new objects move in almost circular “classical” orbits located at distances from 30 to 50 astronomical units from the Sun. Therefore, the outline of the Kuiper belt looks like a thick donut, within which thousands of small celestial bodies move. At a distance of approximately 48 a. That is, from the Sun the density of the Kuiper belt drops sharply. There are no reasons yet to explain why the belt cannot extend beyond this Kuiper barrier. Astronomers cannot decide whether this is really an edge or just a wide interval in which there may be another existing world- the so-called Planet X.

Largest Kuiper Belt Objects

Since 2000, the number of Kuiper Belt objects with diameters from 500 to 1200 km (about half the diameter of Pluto) began to increase rapidly. This gradually led to an understanding of Pluto as one of the largest, but essentially an ordinary member of the Kuiper belt.

– plutoid

Diameter— 2330 km.
Distance to the Sun 14.61 billion km.
Previously known as Xena (Xena). The large eccentricity of Eris's orbit leads to regular changes on its surface and even to gas flows running through the entire dwarf planet.

– plutoid

Diameter— 2390 km.
Distance to the Sun 5.9 billion km.
It was originally considered a planet, but was reclassified as a dwarf planet. In honor of Pluto, the subgroup of those currently known to orbit Neptune are called "plutoids".

– plutoid

Diameter— 1500 km.
Distance to the Sun 6.9 billion km.
Since the emergence of the Solar System, the icy planet has clearly followed its path, without being influenced by Neptune.

– plutoid

Diameter— 1500 km.
Distance to the Sun 7.7 billion km.
Haumea has a highly elongated shape. Perhaps this “top” of the Kuiper belt was born as a result of the collision of two celestial bodies.

- satellite of Pluto

Diameter— 1207 km.
Distance to the Sun 5.9 billion km.
Charon is a satellite of Pluto. It is large in size and only 2 times smaller in diameter than its owner. Not a single satellite in the solar system has such a size in relation to its planet.

– dwarf planet

Diameter— 1100 km.
Distance to the Sun 6 billion km.
Quaoar's orbit is almost circular. Its eccentricity (a measure of the elongation of an ellipse) is less than 0.04, which means that its distance from the Sun changes by less than 8%. In this it is very different from Pluto, whose eccentricity is 6 times greater.

– dwarf planet

Diameter— 946.3 km.
Distance to the Sun 5.8 billion km.
The orbit of Orcus is very similar in parameters to the orbit of Pluto. Interestingly, Orcus is always on the opposite side of the orbit in relation to Pluto. Due to this, Orc is sometimes called the "Anti-Pluto".

– dwarf planet

Dimensions— 859 × 453 km.
Distance to the Sun 6.4 billion km.
Varuna has an elongated shape. Varuna is classified as a classic trans-Neptunian object and follows a nearly circular orbit.

– dwarf planet

Diameter— 650 km.
Distance to the Sun 5.9 billion km.
Like Pluto, Ixion is in a 2:3 orbital resonance with Neptune (it makes two orbits around the Sun in the same time it takes Neptune to orbit three).

The Kuiper Belt should not be confused with the hypothetical Oort Cloud, which is located thousands of times further away. Kuiper belt objects, like scattered disk and Oort cloud objects, are classified as trans-Neptunian objects.

Kuiper Belt- the region of the solar system lying beyond the orbit of Neptune. Extends at distances of 30 - 55 AU. from the sun. The first objects in Kuiper belt were discovered in 1992, excluding the discovery of Pluto in 1930.

Kuiper Belt, like the Main (Inner) asteroid belt between the orbits of Mars and Jupiter, consists of small bodies left over from the early stages of the formation of the Solar System. But, according to modern ideas, Kuiper belt asteroids consist mainly not of rocks, like the asteroids of the Main Belt, but of frozen pieces of water and gases like ammonia and methane.
The Kuiper Belt is not only larger than the Inner Belt in size, but is 20 to 200 times heavier. More than a thousand objects have already been discovered, but it is believed that there are several tens of thousands more undiscovered objects with a diameter of more than 100 km.

Pluto, recently demoted from planets to the category of dwarf planets, also belongs to the Kuiper belt. In addition to Pluto, other dwarf planets are also located here - Makemake and Huamea. Eris seems to be “here” too, but its orbit goes far beyond the belt and simultaneously belongs to the Scattered Disk. The scattered disk can be considered as part of the Kuiper belt, but more often it is understood as a transition zone - from the Kuiper belt to the Orth Cloud.

To date, more than a thousand large asteroids have been discovered in the Kuiper Belt. The estimated number of undiscovered small objects measuring about one hundred kilometers is several tens of thousands. The total mass of the Kuiper belt is tens of times greater than the mass of the inner ring of asteroids.

At one time it was believed that Kuiper belt is a supplier of comets with an orbital period of up to 200 years. which periodically fly into the inner regions of the Solar System. But, according to the latest data, it seems more likely that belt objects have relatively stable orbits, and comets of this type come to us from the much more distant Scattered Disk.
Also, there are suggestions that some small bodies of the Solar System originally arose in the Kuiper belt and only then ended up in the inner regions of the Solar System. Such are, for example, Neptune's satellite Triton and Saturn's satellite Phoebe.

Kuiper belt objects are sometimes divided into three types: 1. Cubiwanos are the classic inhabitants of the Kuiper belt. They have almost circular orbits and their movement is not connected with the movement of other planets. Named after the first open object - 1992 QB1. This also includes, for example, Makemake, Quaoar and Varuna. 2. Plutino - named after the dwarf planet Pluto. Plutino's orbits are in orbital resonance with the motion of Neptune in the form of integers: 1:2, 2:3, 2:5, 3:4, 3:5, 4:5 and so on. This includes bodies such as Orcus, Ixion and Huia. 3. Scattered objects belonging or partially belonging to the Scattered Disk. The most famous representatives: Eris and Sedna.

The Largest Kuiper Belt Objects

Often called the boundary of the solar system.

This disk extends at a distance from 30 to 50 AU (1 AU = 150 million km) from the Sun. Its existence was reliably confirmed not so long ago, and today its research is a new direction in planetary science. The Kuiper Belt was named after astronomer Gerard Kuiper, who predicted its existence in 1951. It is assumed that the composition of most Kuiper belt objects is ice with small admixtures of organic substances, that is, they are close to cometary matter. In 1992, astronomers discovered a reddish speck at a distance of 42 AU. from the Sun - the first recorded object

Kuiper belt

, or trans-Neptunian object. Since then, more than a thousand have been discovered.

Kuiper belt objects are divided into three categories. Classical objects have approximately circular orbits with a slight inclination and are not related to the motion of planets. The most famous minor planets are mainly from among them.

Scattered objects have a large orbital eccentricity and can move away from the Sun by several hundred astronomical units at aphelion. It is believed that such objects once came too close to Neptune, whose gravitational influence stretched their orbits. A prime example of this group is Sedna.

The International Astronomical Union (IAU - International Astronomical Union) has been involved in the nomenclature of planets and satellites since 1919. The decisions of this organization affect the work of all professional astronomers.

However, sometimes the IAU makes recommendations on astronomical issues that excite the general public. One such recommendation was to reclassify Pluto as a dwarf planet. Now classified as a trans-Neptunian object, it is the second largest and most famous of them.

One of the largest Kuiper belt objects is 2002 LM60, also called Quaoar. The name Quaoar comes from the mythology of the Tongva people, who once lived in what is now Los Angeles, and denotes a great creative force. Quaoar orbits with a diameter of about 42 AU. with a period of 288 years. It was first photographed back in 1980, but was classified as a trans-Neptunian body only in 2002 by astronomers Mike Brown and his colleagues at the University of California Institute of Technology

(Caltech) in California.

The diameter of Quaoar is about 1250 km, approximately the same as Charon, which forms a binary system with Pluto. It has been the largest Kuiper Belt object since the discoveries of Pluto in 1930 and Charon in 1978. And it is truly huge: its volume is approximately equivalent to the combined volume of 50,000 asteroids.
Discovered in 2004, 2004 DW, known as Orcus, or Orcus, turned out to be even larger - 1520 km in diameter. The radius of its orbit is about 45 AU.

Another Kuiper belt object 2005 FY9, codenamed “Easterbunny,” was discovered on May 31, 2005 by the same team of Mike Brown from the California Institute of Technology (Caltech). Its discovery was announced on July 29, along with the announcement of two more trans-Neptunian objects: 2003 EL61 and 2003 UB313, also known as Eris.

2003 EL61, which has no official name yet, is roughly the same size but brighter, making it one of the best-known trans-Neptunian objects.

2003 EL61, like Pluto, has an orbital period of 308 years, but its orbit has a greater eccentricity. Due to the high reflectivity of 2003 EL61, it is the third brightest Kuiper Belt object after Pluto and 2005 FY9. It is so bright that it can sometimes even be seen in powerful amateur telescopes, although its mass is only 32% of Pluto's mass. 2003 EL61 is a type of diffuse Kuiper belt object.

Interestingly, 2003 EL61 has two satellites. Although scientists are already calm about the fact that most Kuiper belt objects may turn out to be complex planetary systems.

Eris, first classified as a planet and then transferred together with Pluto to the group of trans-Neptunian objects, is today considered a minor planet and is the largest Kuiper belt object.

The diameter of Eris is 2400 kilometers, which is 6% larger than the diameter of Pluto. Its mass was determined thanks to its satellite - tiny Dysnomia, which has an orbital period of 16 days. Interestingly, at first the discoverers planned to name the dwarf planet and its satellite Xena and Gabrielle in honor of the heroines of the famous series.

In March 2004, a team of astronomers announced the discovery of a small planet orbiting the Sun at a very large distance, where solar radiation is extremely low. Mike Brown, in collaboration with Dr. Chad Trujillo of the Gemini Observatory in Hawaii, and Dr. David Rabinowitz of Yale University, discovered it back in 2003. The discovered minor planet was officially named 2003 VB12, but is better known as Sedna, the Eskimo goddess who lives in the depths of the Arctic Ocean.

Sedna's orbital period is 10,500 years, and its diameter is slightly more than a quarter the diameter of Pluto. Its orbit is elongated, and at its farthest point it is 900 AU away from the Sun. (for comparison, the radius of Pluto’s orbit is 38 AU). Sedna's discoverers classified it as an object in the inner Oort cloud because it never approaches the Sun closer than 76 AU. However, Sedna cannot be considered a classical object of the Oort region, since, even despite its exceptionally elongated orbit, its movement is determined by the sun and objects of the Solar system, and not by random disturbances from the outside. Sedna itself is unusual, because it was quite strange to discover such a large object in the empty extended space between the Kuiper belt and the Oort cloud. It is possible that the Oort cloud extends further into the solar system than previously thought.

Today, Sedna is considered to be one of the diffuse Kuiper belt objects, which also includes 1995 TL8, 2000 YW134 and 2000 CR105. 2000 CR105, discovered eight years ago, is unique for its exceptionally elongated orbit, the semi-major axis of which is almost 400 AU.

Another feature of Sedna is its reddish hue. Only Mars is redder than it. And the temperature on the surface of the amazing small planet does not exceed -240°C. This is very small and it is impossible to directly measure the heat from the planet (infrared radiation), so data from many available sources is used.

The same is true for other Kuiper Belt objects. Moreover, measuring the diameter of these objects is very difficult. Typically, their size is determined by their brightness, which depends on the surface area. It is assumed that the albedo of a minor planet is equal to the albedo of comets, that is, about 4%. Although recent data suggests that it can reach 12%, that is, Kuiper belt objects may turn out to be much smaller than previously thought.

In particular, object 2003 EL61, which is too reflective, is of interest. Five more similar bodies were discovered in approximately the same orbit. The strange thing is that small planets are not massive enough to hold an atmosphere that could crystallize and cover the surface.
On December 13, 2005, a minor planet, 2004 XR 190, was discovered and named Buffy. Buffy's diameter is about 500-1000 km, which is not a record for small planets. Another thing is surprising: unlike scattered Kuiper Belt objects, which have an elongated orbit, 2004 XR 190 has an almost circular orbit (perihelion at a distance of 52 AU from the Sun, aphelion at a distance of 62 AU), inclined at an angle of 47 degrees to the plane of the ecliptic. The reason for the emergence of such a trajectory is still unclear to astronomers.

There is still an opinion among some astronomers that within the Kuiper belt there is a certain massive body, at least the size of Pluto.

Back in the first half of the last century, scientists predicted the existence of Neptune based on the disturbances it exerted on Uranus. Later, American astronomer Percival Lowell tried to discover a planet beyond Neptune that could distort its trajectory. And indeed, Pluto was discovered in 1930. True, it immediately became clear that its mass is too small (0.002 Earth’s) to significantly disturb the movement of massive Neptune. Therefore, the suspicion remained that the mysterious planet “X” was not Pluto, but a larger minor planet that had not yet been discovered.

Subsequently, it turned out that deviations in the movement of Pluto were only a measurement error. Of course, in theory, Planet X could exist if it is small and distant enough to have a noticeable effect on Pluto's trajectory. But the closest Kuiper Belt object to us may be Saturn's moon Phoebe. It revolves around the planet in

reverse side

, which suggests that Phoebe was not formed in the protoplanetary disk of Saturn, but somewhere else and was later captured by it.

Behind the Kuiper belt there is another more global formation - the Oort cloud. The idea of ​​such a cloud was first proposed by the Estonian astronomer Ernst Epic in 1932, and then theoretically developed by the Dutch astrophysicist Jan Oort in the 1950s, after whom the cloud was named. It has been suggested that comets arrive from an extended spherical shell, consisting of icy bodies, on the outskirts of the Solar system. This huge swarm of objects is today called the Oort cloud. It extends over a sphere with a radius of 5,000 to 100,000 AU.

Consists of billions of icy bodies. Occasionally, passing stars disturb the orbit of one of the bodies, causing it to move around inner part Solar system as a long-period comet.

Such comets have a very large and elongated orbit and, as a rule, are observed only once. One example of long-period comets are comets Halley and Swift-Tuttle. In contrast, short-period comets, whose orbital period is less than 200 years, move in the plane of the planets and come to us from the Kuiper belt.