National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
Dwarf Planets: Overview
   Overview   Dwarf Planets   Gallery   Missions   News   FAQ 
Illustration showing dwarf planet sizes compared to Earth.
An artist's concept showing the size of the best known dwarf planets compared to Earth and its moon (top). Eris is left center; Ceres is the small body to its right and Pluto and its moon Charon are at the bottom.

Dwarf planets are round and orbit the Sun just like the eight major planets. But unlike planets, dwarf planets are not able to clear their orbital path so there are similar objects at roughly the same distance from the Sun. A dwarf planet is much smaller than a planet (smaller even than Earth's moon), but it is not a moon. Pluto is the best known of the dwarf planets.

10 Need-to-Know Things About Dwarf Planets:

  1. If the sun were as tall as a typical front door, Earth would be the size of a nickel and dwarf planets Pluto and Eris, for example, would each be about the size of the head of a pin.
  2. Dwarf planets orbit our sun, a star. Most are located in the Kuiper Belt, a region of icy objects beyond the orbit of Neptune. Pluto, one of the largest and most famous dwarf planets, is about 5.9 billion km (3.7 billion miles) or 39.48 AU away from the sun. Dwarf planet Ceres is in the main asteroid belt between Mars and Jupiter.
  3. Days and years vary on dwarf planets. One day on Ceres, for example, takes about nine hours (the time it takes for Ceres to rotate or spin once). Ceres makes a complete orbit around the sun (a year in Ceresian time) in about 4.60 Earth years.
  4. Dwarf planets are solid rocky and/or icy bodies. The amount of rock vs. ice depends on their location in the solar system.
  5. Many, but not all dwarf planets have moons.
  6. There are no known rings around dwarf planets.
  7. Dwarf planets Pluto and Eris, for example, have tenuous (thin) atmospheres that expand when they come closer to the sun and collapse as they move farther away.
  8. The first mission to a dwarf planet is Dawn (to Ceres).
  9. Dwarf planets cannot support life as we know it.
  10. Pluto was considered a planet until 2006. The discovery of similar-sized worlds deeper in the distant Kuiper Belt sparked a debate that resulted in a new official definition of a planet that did not include Pluto.
Homework? We can help. Link to dwarf planets homework help.
People Spotlight
Marina Brozovic Marina Brozovic
"My first personal connection with outer space was the first time I became acutely aware of the night sky -- I was no older than six at the time." Read More...
Science & Technology Features
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writers: Courtney O'Connor and Bill Dunford
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> NASA Advisory Council
> Open Government at NASA
Last Updated: 29 Apr 2015