---
title: 'What is a Planet?'
url: 'https://grav.alicesastroinfo.com/blog/what-is-a-planet'
markdown: 'https://grav.alicesastroinfo.com/blog/what-is-a-planet.md'
date: '2006-08-25'
description: 'What is a Planet? IAU Definition – August 24, 2006 The International Astronomical Union (IAU) voted on the definition of planet on August 24, 2006. A Planet is: 1. Orbiting a star. 2. Big enough to be spherical – an IAU process will decide if any new bodies discovered are planets or not. 3. Massive…'
taxonomy:
  category:
    - 'AstroInfo Article'
  tag:
    - 'Pluto Debate'
    - 'Solar System'
---

# [What is a Planet?](https://grav.alicesastroinfo.com/blog/what-is-a-planet)

   25th Aug 2006   [Pluto Debate](https://grav.alicesastroinfo.com/tag:Pluto%20Debate#body-wrapper) [Solar System](https://grav.alicesastroinfo.com/tag:Solar%20System#body-wrapper)  

**What is a Planet?**

**IAU Definition – August 24, 2006**

**The International Astronomical Union (IAU) voted on the definition of planet on August 24, 2006.**

**A Planet is:**

**1. Orbiting a star.**

**2. Big enough to be spherical – an IAU process will decide if any new bodies discovered are planets or not.**

**3. Massive enough to clear its orbit of similar bodies.**

**A Dwarf Planet is:**

**4. Orbiting a star.**

**5. Big enough to be spherical.**

**6. Not massive enough to clear its orbit of similar bodies.**

**7. Not a moon.**

**In addition, other categories can be used to be more specific:**

**A Plutonian (a new official category, but not an official name):**

**8. A dwarf planet similar to Pluto in size and orbit.**

**A Small Solar System Body is:**

**9. Anything that’s not a planet.**

**What does this mean?**

**Planets (as currently recognized by the IAU):**

**Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune**

**Plutonians:**

**Pluto, Eris**

**Dwarf Planets:**

**Ceres, Pluto, Eris**

**Planets that could be added under this definition:**

**The bodies discovered over the last few years: “Sedna,” “Quaoar,” and many other recently discovered Trans-Neptunian Objects.**

**The current asteroids Vesta, Pallas, Hygeia**

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