10 interesting facts about the Kuiper belt

(ORDO NEWS) — This structure, known as belt Edgeworth-Kuiper, extends beyond the orbit of the planet Neptune a distance of about 50-55 AU (one astronomical unit (AU) is equal to 149 599 300 kilometers) from the sun . The Kuiper Belt is composed primarily of small icy bodies, including the dwarf planets Pluto , Haumea, and Makemake.

Currently, much about the origin of the Kuiper belt remains a mystery. However, it is known that Triton and Phoebe, satellites of the planets Neptune and Saturn, respectively, are probably objects of the Kuiper belt, which in the distant past were captured from the host planets. Below are 10 more interesting facts about the Kuiper belt that you may not have known.

Gerard Kuiper did not open the Kuiper belt

And although the Kuiper Belt is named after the Dutch-American astronomer Gerard Kuiper, he did not discover it and was not even the first to predict or even suggest its existence.

Although the historical record is not entirely clear as to who first predicted the existence of the structure, it is generally accepted that its existence was assumed as early as the 1930s, shortly after Clyde Tombaugh discovered Pluto. However, the discovery of the structure is attributed to astronomers David Jewitt and Jane Lu, who discovered the first Kuiper belt object in 1992 (15760) 1992 QB1.

Short-period comets do not form in the Kuiper belt

Although the Kuiper belt was long thought to be the source of all or most short-period comets, research has shown that this is not true. Improved techniques led to the discovery that short-period comets primarily originate from the scattered disk , a distant region of the solar system that is associated with the Kuiper belt.

The scattered disk objects were created by the planet Neptune as it moved through what is now the Kuiper Belt, migrating away from the Sun. This led to the dispersion of a large number of objects that are still subject to Neptune’s gravitational disturbances.

The Kuiper Belt is toroidal

Except for a portion of the scattered disk structure, but including its peripheral regions, the Kuiper belt encompasses an area between 30 and 55 AU. from the sun. However, its densest part extends from the 2: 3 * average motion resonance to the 1: 2 * resonance at a distance of about 48 AU. from the sun.

The Kuiper Belt is a fairly dense structure; the main concentration of objects extends about ten degrees on either side of the plane of the ecliptic, and a more sparse population of bodies extends several tens of degrees further. In general, the Kuiper belt is inclined 1.86 degrees relative to the ecliptic and looks more like a torus (donut) than a flat belt or ring.

* In this context, “resonance” refers to the region or distance from the Sun at which objects in the Kuiper belt are in orbital resonance with the planet Neptune.

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The Kuiper Belt has two distinctly different populations of objects

The region is between 42 and 45 AU. from the Sun is called the “classical Kuiper belt”, and in this area there are two completely different populations of objects:

  • The first group is known as “cold bodies” and is represented by objects with nearly circular orbits that are usually tilted less than 10 degrees from the ecliptic.
  • The second group, known as “hot bodies”, is represented by objects whose orbits can be tilted 30 degrees, or sometimes more, relative to the ecliptic.

Note that the words “cold” and “hot” do not refer to the relative temperature of the two populations, but to the difference in their orbital velocities, similar to how gas particles behave when heated.

More than 99% of the mass of the Kuiper belt is missing

Based on the generally accepted model for the formation of the solar system , it was predicted that the Kuiper belt should have a mass of about 30 Earth masses. However, the structure, according to modern observations, has a mass of 1/25 to 1/10 of the mass of the Earth.

This discrepancy is important, since the missing mass is necessary for objects larger than 100 kilometers in size to exist there at all.

Simply put, if the Kuiper belt always had the observed low mass, then large bodies in its structure would never have formed. However, Pluto, Haumea and Makemake, mentioned above, do exist. Studies have shown that the current influence of Neptune could not displace such a large mass from the structure, although in the distant past, when the planet migrated from the Sun, it could displace a significant part of the mass of the Kuiper belt.

The missing mass of the structure remains open, but current theories suggest that passing stars may be involved, disrupting the structure of the Kuiper belt or, probably, an undiscovered massive planet (or planets).

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Triton was formed in the Kuiper belt

Since Neptune’s moon Triton is only 14% larger than Pluto (a confirmed Kuiper belt object) and appears to have roughly the same composition as Pluto, most researchers agree that Triton was formed in the Kuiper belt and was then captured by Neptune, who migrated from the sun.

However, capturing such a large object is not an easy task, so there is still debate about the mechanisms that would allow Neptune to do this. Recent theories suggest that Triton was part of a binary system, and that one object was excluded from the system when Neptune invaded both.

Neptune controls the structure of the Kuiper belt

Neptune’s gravitational field has a noticeable effect on the structure of the Kuiper belt. In fact, this effect is so strong that at distances of 40 to 42 AU. from the Sun, no object can maintain a stable orbit due to the influence of Neptune’s gravity.

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Kuiper Belt ends with a “cliff”

The 1: 2 resonance region in the Kuiper belt corresponds to a distance of about 50 AU. from the Sun, and theories predict that the number of objects with a diameter of more than 100 km outside this region should be twice as much as it actually is. In fact, there are very few objects of any noticeable size in the area known as the Kuiper Cliff.

Moreover, convincing evidence was found that the absence of large objects is not associated with a systematic error in observations and calculations. However, to date, no one has yet proposed a reliable theory that could explain the existence of Kuiper Cliff.

The exact origin of the Kuiper belt remains unknown

It is known that the Kuiper belt consists of millions of icy planetesimals, but so far no one knows how these bodies ended up where they are now.

Structures similar to the Kuiper belt are not unique to the solar system

Structures such as the Kuiper belt often appear around other stars. Moreover, observations have shown that about 15-20% of sun-like stars are surrounded by regions of excess infrared radiation, which indicates the hot dust disks that surround these stars.


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