National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
Planets
Dwarf Planets: Overview
   Overview   Dwarf Planets   Gallery   Missions   News   FAQ 
Illustration showing dwarf planet sizes compared to Earth.
This artist's concept shows dwarf planets Eris, Pluto and Ceres in comparison to Earth. Pluto's moon Charon also is shown.

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 no 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.
    Color illustration showing how much smaller than Earth and the moon.
    Known dwarf planets are smaller than Earth's moon.
  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 have tenuous (thin) atmospheres that expand when they come closer to the sun and collapse as they move farther away. It is possible dwarf planet Ceres has an atmosphere.
  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 a 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.
Resources
Calendar
People Spotlight
Marc Rayman Marc Rayman
"My interest in space and science only grew stronger as I grew older, and I followed all aspects of space exploration as closely as I could while ..." Read More...
Headlines
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 Writer: Autumn Burdick
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
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 28 Apr 2014