It is pretty easy to forget how small we are in the grand scheme of outer space, and even in our own solar system. There are many different structures in our solar system that orbit around the Sun, located billions of miles away. One of the largest structures we have in our solar system is the Kuiper Belt. Where is the Kuiper Belt located and what’s in it?
The Kuiper Belt is a region in space located near the orbit of Neptune. The inner edge of the Kuiper Belt is roughly 2.8 billion miles from the Sun. The outer edge of the belt can stretch as far out as 93 billion miles away or more. This region of space contains icy objects, rocks, dwarf planets, moons, and comets.
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What Is the Kuiper Belt?
The Kuiper Belt is a ring-shaped region in our solar system made up of rocky and icy objects. Scientists split the Kuiper Belt up into multiple regions, including the inner edge, inner-main region, and the outer edge that overlaps the main region. The outer layer is called the scattered disk.
All of the objects in the Kuiper Belt orbit the Sun, just like our planets. Most of the objects in this structure are greatly affected by Neptune’s orbit and gravity. The Kuiper Belt is also one of the main sources where comets and asteroids that pass near Earth come from. Fragments of Kuiper Belt objects are thrown out into our solar system due to collisions or solar wind.
The first time a spacecraft entered the Kuiper Belt was in 1983 with NASA’s Pioneer 10
spacecraft. Pioneer 10 was also the first spacecraft to explore space beyond Neptune. In 2015, NASA’s New Horizons was the first spacecraft to visit a Kuiper Belt object. New Horizons’ mission is to explore the Kuiper Belt and its objects.
Where Is the Kuiper Belt Located in Our Solar System?
The Kuiper Belt is located in the outer zone of our solar system, a little over 2.7 billion miles away from Earth. The inner zone of our solar system consists of rocky planets and ends at Mars. Sometimes the Kuiper Belt is often referred to as the “third zone” of our solar system because it begins outside of the last planet in our solar system, Neptune.
The scattered disk region of the Kuiper Belt is located about 93 billion miles away from the Sun, with some objects in the belt orbiting even further beyond. This makes the Kuiper Belt one of the largest structures that we have in our solar system, alongside the Oort Cloud. The Oort Cloud is very similar to the Kuiper Belt that also surrounds our solar system, but is much farther away.
Objects in the Kuiper Belt
Objects within the Kuiper Belt are referred to as Kuiper Belt objects (KBOs) or trans-Neptunian objects (TNOs). These objects consist of dwarf planets, comets, and rocky, icy objects. Pluto and Eris are two dwarf planets located in the Kuiper Belt. So far, all the objects that scientists have discovered in the Kuiper Belt are all smaller than the Earth’s Moon.
In 2006, it was decided that Pluto was no longer considered the ninth planet in our solar system and was deemed a dwarf planet. Pluto is one of the largest objects in the Kuiper Belt and was also the first KBO to be discovered.
The objects within the Kuiper Belt are not evenly distributed and range widely in shape, color, and size. Scientists categorize KBOs mainly by studying how the different groups of objects orbit and have interacted with Neptune. The main categories of KBOs include:
- Classical KBOs
- Resonant KBOs
- Scattered Disk objects
- Detached objects
Classical KBOs
The name classical KBOs stems from the idea of what scientists originally thought the Kuiper Belt looked like before further exploration and discovery of its objects. Classical KBOs are split up into two sub-categories, called hot and cold. These sub-categories do not refer to the temperature of the objects or region, but rather the orbits of the objects and their relationship with Neptune’s gravitational pull.
Classical KBOs maintain an average distance of about 3.72 to 4.65 billion miles from the Sun. Cold classical KBOs generally maintain an average distance from the Sun throughout their entire orbit.
Hot classical KBOs do not have as steady of an orbit, with some parts of their orbit being closer or farther away from the Sun. Most of the objects in the Kuiper Belt are categorized as classical KBOs.
Resonant KBOs
Neptune’s gravitational pull greatly impacts a large number of objects in the Kuiper Belt. Objects that are most affected by Neptune’s gravity are called resonant KBOs. The orbit of these objects have a close connection to the orbit of Neptune.
Depending on their relative distance from Neptune, resonant KBOs complete a certain number of orbits based on Neptune’s orbit around the Sun. Scientists classify these measurements by using ratios. For example, for every three orbits Neptune completes around the Sun, Pluto completes two orbits. There are many Kuiper Belt objects that also have this 3:2 ratio like Pluto, so scientists gave them their own sub-category called plutinos.
Scattered Disk Objects
Scattered disk objects are located on the outer edge of the Kuiper Belt. These objects have been thrown out at farther ranges in this outer region by Neptune. The dwarf planet, Eris, is located in this area and is the largest KBO discovered in the scattered disk region so far.
Many of the objects within the scattered disk have been lost over time, mostly by being thrown out into space due to Neptune. Scientists consider this region less stable because it’s still evolving and expected to lose more objects.
Detached Objects
Detached objects differ from other KBOs because they don’t orbit any closer than 3.72 billion miles from the Sun. Since the orbits of detached objects greatly differ from others in the Kuiper Belt, scientists believe the orbits are affected by another force. One theory is that there could be an undiscovered planet, nicknamed Planet 9, in which its orbit is affecting the orbits of the detached objects.
One of the farthest Kuiper Belt objects in this category is called Sedna. Scientists use astronomical units (AU) to measure distances in space. One AU is the equivalent of 93 million miles, or the distance from the Earth to the Sun. The closest Sedna comes to the Sun in its orbit is about 76 AU, with the farthest point in orbit reaching distances of about 1,200 AU.
Other objects that are a part of the Kuiper Belt include centaurs, moons, and binaries. Centaur objects interact closely with the gravity of Jupiter and Neptune. These objects are thought to have come from the Kuiper Belt, but have escaped and are destined to become comets.
There are many KBOs that have their own moons, including Pluto and Eris. Binaries are Kuiper Belt objects that orbit close together around another object. Some are so close together that they attach, forming a contact binary.
How Did the Kuiper Belt Form?
Scientists believe that the Kuiper Belt was formed by leftover remains following the formation of our solar system. Astronomers also believe that if Neptune did not exist, objects that make up the Kuiper Belt could have melded together to form other planets. Neptune’s gravity has had a great impact on how the objects in the Kuiper Belt behave.
The four gas giants of Neptune, Uranus, Saturn, and Jupiter are believed to have contributed to much of the Kuiper Belt’s loss of objects over an extended period of time. When the solar system was created, these four planets shifted around which ultimately affected each other’s orbits. Much of the Kuiper Belt’s mass has been lost as a result of these changes in positions of the gas giants.
Why Is the Kuiper Belt Important?
The Kuiper Belt offers scientists the opportunity to learn more about the history of our solar system and the universe. In 2019, scientists were able to use the New Horizons spacecraft to explore a very distant Kuiper Belt contact binary object up close, called Arrokoth.
If further advanced technology and spacecraft are developed in the future, scientists may have the opportunity to grab samples from KBOs. The objects in the Kuiper Belt are very cold because they are so far away from the Sun. This means that the objects may hold preserved samples that could give scientists more insight into the creation of our solar system that formed 4.5 billion years ago.
Overview: Where Is the Kuiper Belt Located?
The Kuiper Belt is located billions of miles away in the outer region of our solar system. The inner edge of the Kuiper Belt begins at Neptune’s orbit, a little over 2.7 billion miles away from Earth. The outer edge, or scattered disk, of the Kuiper Belt stretches on for tens of billions of miles.
Within the Kuiper Belt is a wide array of icy objects, including dwarf planets, asteroids, rocks, comets, and moons. Scientists have been able to identify more than 2,000 objects, but it is estimated that there could be millions floating around within the Kuiper Belt.