Dwarf Planets
The International Astronomical Union (IAU) decided in 2006 to create a new classification of celestial bodies: Dwarf Planets. Here are the criteria the IAU has set forth to define a planet:
- Heliocentric Orbit - A planet orbits the sun.
- Hydrostatic Equilibrium - A planet needs to be large enough for it's gravity to make it spherical.
- Dominant Orbital Body - A planet does not share it's orbit.
This new term defines all bodies that look like a planet, but fall short of the planetary definition in some way. For example, Ceres shares it's orbit with the asteroid belt (Planets do not share orbits). Pluto shares it's orbit with Charon and the Kuiper belt. Here is a list of the Dwarf Planets we have so far:
Name | Distance (AU) | Diameter (km) | Year |
---|---|---|---|
Ceres | 2.77 | 974.6 | 1801 |
Pluto | 39.48 | 2,306 | 1930 |
Haumea | 43.34 | 1150 | 2005 |
Makemake | 45.79 | 1500 | 2005 |
Eris | 67.67 | 2400 | 2005 |
New Candidates
The Dwarf Planets above were only an Initial Offering from the IAU to help define the term. There are many other bodies that fit the criteria of Dwarf Planet and will be considered:
Name | Distance (AU) | Diameter (km) | Year |
---|---|---|---|
Orcus | 39.12 | 1,200 | 2004 |
Ixion | 39.65 | 900 | 2001 |
Huya | 39.76 | 480 | 2000 |
Varuna | 42.90 | 850 | 2000 |
2002 TX300 | 43.11 | 800 | 2002 |
Quaoar | 43.58 | 1,200 | 2002 |
2002 AW197 | 47.30 | 900 | 2002 |
2002 TC302 | 55.02 | 1,100 | 2002 |
1996 TL66 | 82.90 | 600 | 1996 |
Sedna | 88 | 1500 | 2003 |
Charon | 39.48 | 603.5 | 1978 |
Advertisement: