Asteroid Belt vs. Kuiper Belt vs. Oort Cloud

Have you ever wondered how they differ?

The Asteroid Belt, shown above, consists of hundreds of thousands of rocks, with all kinds of different shapes, ranging in size from the Dwarf Planet Ceres at 950 Km in Diameter, down to small bits the size of dust particles.  It lies between Mars and Jupiter.


The Kuiper Belt (pronounced Kai-per) consists of Icy rocks, and it a major source of short-period Comets in the Solar system.  Extending beyond the planet Neptune, Pluto was discovered to be one of the largest objects in the belt.

Credit: ESA

The mysterious Oort cloud is a collection of Comets, thought to extend far beyond the planets of the Solar System.  ‘Cloud’ is a correct term, as the Oort comets are distributed spherically about the Sun, possibly extending as far as half way to the next star.  The Oort orbits are not regular or planar like the Asteroid and Kuiper belts, and are often perturbed through gravitational interactions during their long journeys on highly eccentric orbits.

The belts and the Oort cloud show just how many rocks there are in the Solar System.  The Planets may be the largest objects, but they are certainly not alone.

26 thoughts on “Asteroid Belt vs. Kuiper Belt vs. Oort Cloud

  1. I’ve long believed that the asteroid belt was formed by the explosion of a planet that used to orbit between Mars and Jupiter. If that’s the case, I’m wondering if the shrapnel from that event may have traveled far enough out to form the Kuiper belt as well… and even the Oort cloud?….

    1. There are definitely ideas about migration of objects in the early solar system, and especially with Jupiter being such a huge gravitational shepherd, its likely that many perturbed objects have found their way to the Kuiper Belt. If there was a planet that formed between Mars and Jupiter, questions remain. How did it form with Jupiter so close-by? If it did form, what suddenly changed to allow Jupiter to tear it apart? It depends on the formation of Jupiter and it’s role in the early solar system, and it’s equally likely that no planet ever formed in the asteroid belt because anything that became large enough would be torn apart by Jupiter first.

    2. JaCarious Smith

      I have too its kind of weird that its like that because sometimes I think the same exact thing so u arent the only one.

  2. lala

    Beutiful pic

  3. Fred Moore

    The asteroid belt like the Trojan locations are just spherical harmonic ‘Low” points in the Solar System. The Earth too has 5 spherical harmonic low points L1…L5, 4 of which are slightly stable. Its not surprising that Jupiter, so Large, has many L points with 2 low points being stable enough to harbour non-acreted matter (Trojans) over time.
    I suspect that the asteroid & kuiper belts and oort cloud are just L Rings of the Sun similar to d,f & g shells of atomic orbitals which are the spherical harmonic solutions of atoms.

    I suspect that from the very beginning of the proto-solar system that these spherical harmonics were mathematically pre-mapped based on initial density, total mass and angular momentun in much the same way as the large variety of atoms are in the periodic table.

    1. JaCarious Smith

      true, indeed

  4. JaCarious Smith

    where is the picture of the Oort cloud?

    1. It’s one of those things we can never take a picture of. It’s like a snow globe with us in the middle.

  5. Celeste Kent

    Since the sun is such an immense electro-magnetic generator, and the solar wind which blasts out in every direction from the sun, is it possible that there is some resonance distance represented by the three different collections of rocky debris: asteroid, Kuiper and Oort distances? That to understand the dynamics of the entire system one needs to study electro-dynamics and apply those principles instead of gravity?

  6. Ebony

    I always find that studying such concepts as these makes you realise just how insignificant and almost parasitical our species is.

    1. Chris

      Awesome remark. So parasitic

    2. On the other hand who else but us even has the imagination to ask these questions?

      1. “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” – Arthur C. Clarke

        Very likely some alien civilizations out there though 🙂

  7. Jim

    Has the Oort Cloud ever been imaged? How do we know it exists?

    1. Great Question! The Oort cloud is all around us, so imaging it is near impossible. It’s like trying to photograph an entire forest when you’re walking through it. You can photograph and study individual trees, but otherwise you can’t really see the entire thing.

      The Oort cloud has been studied through observations of comets that have passed near the Earth. The rate of appearance of these comets and study of the interactions required to send them to the inner solar system lead to a theoretical calculation for how many objects should be in the outer solar system beyond all the planets – this is a huge number and represents the Oort cloud, as they are thought to be roughly spherically distributed.

      I hope this answer makes sense – thanks for the comment and question!

  8. Julianna Lira

    Which is the biggest? The Oort CLoud, the Kuiper belt, or the Asteroid belt?

    1. The Oort cloud by a lot! Covers a huge amount of volume, almost halfway to the next star!

  9. Larry

    I say we need as a species more info than we have been given! God bless those who are given the need for more info! In the end the seekers will survive those who care little for facts ! God bless the diggers!!!!

  10. Muhammad anwar

    What is thickness of Asteroid belt.

    1. Thanks for your question!

      The thickness varies quite a lot as the belt is made up of several thousand asteroids and millions of smaller rocks. Because of this it can be difficult to determine a boundary. It’s similar to walking into a forest. There isn’t a defined edge where you cross a line and now there are hundreds of trees, it’s gradual. The asteroid belt is the same. It’s between Mars (1.5 AU from Sun) and Jupiter (5.2 AU from Sun), and generally is said to be about 1 AU wide (about 150 Million Km).

  11. Dr.Sam George

    Do the Kuiper Belt and the Oort Cloud overlap or is there a definite gap between them? If there is a gap, what is that called and how big is it? If there is not a gap, would that not make the Kuiper Belt perhaps a specialized part of the Oort Cloud?

    1. This is a very good point. In Space, there are no technical hard boundaries. With the Kuiper Belt, it’s often defined through the density of object, the greatest density being past the orbit of Neptune and several times farther from the Sun. However, any defined end to the Kuiper belt is very close to the Sun compared to the Oort cloud, which extends as much as two light years from the Sun (4000 times as far as the Kuiper Belt), and is assumed to be a uniform density give or take.

      The difference in these belts from an astronomer’s perspective lies in their formation. The Oort cloud and the Kuiper Belt formed from different material at different times during the evolution of the Solar System. This is what truly sets them apart.

      I hope this helps. Thanks for the question!

  12. Sirjoat

    What is a minimum time to transit from the Kuiper Belt to the moon. (Moving objects for terraforming) Constant acceleration no deceleration required.

    1. Good question! It depends on where you are in the Kuiper Belt, but since you’re asking for the minimum transit time, we should assume Neptune’s orbit as the inner boundary of the belt (I doubt this is actually the case but we’re doing a simple calculation). The Moon would be at Earth’s orbit, and we will assume Earth and Neptune are in line with the Sun, to ensure the shortest distance possible. The distance between them would be ~4.3e9 Km. The New Horizons spacecraft was the fastest to leave Earth, at 16.25 km/s. Doing the simple math (assuming constant velocity the whole way) you could make the trip in ~8.4 Earth years.

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