We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Dwarf Planet?

Michael Anissimov
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A dwarf planet is a new category of celestial body created by the International Astronomers Union in 2006. It includes celestial bodies massive enough to be spherical, in orbit around the Sun, which are not satellites. The crucial factor dividing a planet from a dwarf planet is that a planet must have succeeded in clearing the area of its orbit from debris and other objects, whereas a dwarf planet has not.

When the category of dwarf planet was created, three bodies were immediately classified as such: Ceres, the largest asteroid, now a dwarf planet; Pluto, in the Kuiper belt, demoted from the status of planet; and Eris, a scattered disc object located far beyond the orbit of Pluto. It was the discovery of Eris that partially prompted the International Astronomers Union to more precisely define what they meant by the word “planet.”

Despite the name “dwarf planet”, dwarf planets are not considered a subset of planets, but rather in a different category altogether. Objects still smaller than dwarf planets, for instance, those lacking sufficient mass to be spherical, are called small solar system bodies, which includes comets and asteroids.

Although only three dwarf planets recognized, astronomers suspect that there many be as many as 200 in the far reaches of the solar system. There are numerous potential candidates for dwarf planethood which must be studied closer to confirm their status. For a celestial body to be roughly spherical requires a diameter of at least 400 km. The smallest known spherical body today is the moon Mimas.

There are numerous trans-Neptunian objects with diameters larger than 400 km: Varuna, Orcus, Ixion, Quaoar, 2003EL61, 2005FY9, and several others. Although we can estimate their diameter, it is more difficult to estimate whether they are roughly spherical or not. This will require more powerful telescopes. There are also several large asteroids which may be dwarf planets: Vesta, Pallas, and Hygiea, the second, third, and fourth largest asteroids after Ceres.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology, astronomy, chemistry, and futurism to his articles. An avid blogger, Michael is deeply passionate about stem cell research, regenerative medicine, and life extension therapies. His professional experience includes work with the Methuselah Foundation, Singularity Institute for Artificial Intelligence, and Lifeboat Foundation, further showcasing his commitment to scientific advancement.
Discussion Comments
By anon123996 — On Nov 04, 2010

2005 FY9 and 2003 EL61 are Makemake and Haumea. Maybe this article was written before they were named. All minor planets like asteroids and TNO:s including dwarf planets get a provisional designation before they get a real name. Asteroid Apophis for example was known as 2004 MN4.

By calabama71 — On Oct 25, 2010

@wesley91: Thanks for that additional information!

By wesley91 — On Oct 25, 2010

There are actually five dwarf planets recognized by the IAU, not three. The five dwarf planets are Pluto, Ceres, Haumea, Eris, and Makemake. Only Ceres and Pluto have been studied in detail. Eris was added to the category since it is bigger than Pluto.

Haumea and Makemake were accepted as dwarf planets because they display absolute magnitude of less than +1 and a minimum diameter of 838km. Those are conditions set by the IAU.

Research does reveal three distinct dwarf planet, which are the asteroid Ceres, Eris, and planet Pluto. By definition, there are many other objects in our solar system that would qualify as being dwarf planets.

By anon53819 — On Nov 24, 2009

this is pretty good but make it easier to use for assignments. thanks!

By anon37826 — On Jul 22, 2009

this is a good webpage! but try to focus more on the topic and make it more easier to understand for assignments!!

Michael Anissimov
Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology...
Learn more
All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.