ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

What is a Dwarf Planet?

Updated on July 22, 2011

Definition of a Dwarf Planet

Dwarf planets are roughly spherical objects that orbit the Sun. They are smaller than planets. The defining difference is that a planet has sufficient gravity to have cleared its surroundings of debris. Smaller bodies orbiting in the neighbourhood around a planet are gravitationally attracted to it. They end up either colliding with the planet and being absorbed, or becoming a satellite of the planet.

Dwarf planets by definition do not have sufficient gravitational pull to attract and assimilate all of the smaller bodies in their surroundings.

Five objects in the Solar System have been identified as dwarf planets by the IAU (International Astronomical Union).


Pluto used to be labelled as a planet. Astronomers reclassified Pluto as a dwarf planet after discovering that it lies in a region filled with other similarly sized objects. This region has been named the Kuiper belt after astronomer Gerard Kuiper.

Pluto and its moon Charon, as photographed by the Hubble Space Telescope.
Pluto and its moon Charon, as photographed by the Hubble Space Telescope. | Source


Ceres is an icy dwarf planet located in the asteroid belt that lies between Mars and Jupiter. It is due to be visited in 2015 by NASA's Dawn satellite. This probe is on a mission to study the structure and composition of two objects in the asteroid belt – Ceres and Vesta. It is hoped that studying the development of these two protoplanets could help astrophysicists to better understand the evolution of the Earth. Ceres is the only dwarf planet in the inner Solar System – the region closer to the Sun than Jupiter. All of the others are located in the Kuiper belt.

Artist's impression of Haumea with its moons, Hi'iaka and Namaka.
Artist's impression of Haumea with its moons, Hi'iaka and Namaka. | Source


Haumea is a dwarf planet that rotates very quickly, taking less than 4 hours to spin around on its axis. It is the fastest-rotating planet in the Solar System. Haumea is unusual because it is shaped like an ellipsoid, which is longer and thinner than a sphere. It has two moons – Hi'iaka and Namaka.


Makemake's name is borrowed from a god who is worshipped by the people of Easter Island. It was given this name because it was discovered at Easter time in 2005. Although it now has a name fit for a god, for three years after its discovery astronomers used to call the planet “Easterbunny”.


Eris is the largest of the dwarf planets that have been identified so far in the Solar System, although its diameter is still less than one fifth that of the Earth.

Future Dwarf Planets

Expect to see the number of dwarf planets increasing in years to come. There are several objects in the solar system that might fit the definition of dwarf planet. Most of these are located in the Kuiper belt. As the discoveries of planets in other solar systems mount up, it is only a matter of time before the first extra-solar dwarf planet is identified.


    0 of 8192 characters used
    Post Comment

    • topquark profile imageAUTHOR


      6 years ago from UK

      You were right, quarks can't be seen. My userpic is actually a picture of the tracks left by thousands of particles that are created when two nuclei collide in a particle accelerator. A lot of those particles are created by interactions between quarks though, so it is related! Thanks for the feedback, it's much appreciated.

    • profile image


      6 years ago

      After helping special ed students in a science class where I learned more than I ever knew before about red dwarfs, super novas, etc., I found that my interest in the scientific world, especially about the universe had been piqued. Saw your picture of a quark and had to come look/see. Until yesterday, I did not even know a quark could be seen. So interesting! Thanks for the interesting hub!

    • kschimmel profile image

      Kimberly Schimmel 

      6 years ago from North Carolina, USA

      Now I know the distinction between a planet and a dwarf planet. Thank you!

    • TheWorldNow profile image


      7 years ago from Washington DC

      I didn't realize we had so many dwarf planets in our solar system! Thanks for the good, informative, read.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)