The image below compares the sizes of the largest outer solar system objects. It includes:

• the Earth, the Moon, and Mercury (the smallest planet other than Pluto), for reference;
• the three largest asteroids: (1) Ceres, (2) Pallas, and (4) Vesta;
• Triton, the largest satellite of Neptune;
• Pluto, its large satellite Charon, and its two smaller satellites Hydra and Nix;
• the newly discovered object Eris (=2003 UB313) with its satellite Dysnomia;
• the two other newly discovered large objects: (136108) 2003 EL61 (with its two satellites) and (136472) Makemake (=2005 FY9);
• the distant object (90377) Sedna;
• the other known trans-Neptunian objects that are at least 650 km in diameter;
• a few other illustrative objects: (28978) Ixion and both components of the binary (47171) 1999 TC36; and
• the U.S. state of Texas for comparison.

Relative sizes, brightnesses, and colors are shown.

As of 24 August 2006, the IAU classifications for the above objects include:

• planet: Earth, Mercury
• dwarf planet: Pluto, Ceres, Eris; status pending for:
  • trans-Neptunian objects (20000) Varuna, (28978) Ixion, (55565) 2002 AW197, (55636) 2002 TX300, (90377) Sedna, (90482) Orcus, (50000) Quaoar, (136108) 2003 EL61, (136472) Makemake,
  • asteroids (2) Pallas and (4) Vesta (plus (10) Hygiea, not shown)
• small solar system body: includes remaining asteroids and trans-Neptunian objects
• natural satellite: Moon, Triton (both satellites of planets), Charon, Hydra, Nix, Dysnomia (satellites of dwarf planets), and unnamed satellites of (136108) 2003 EL61 and (47171) 1999 TC36 (satellites of other trans-Neptunian objects)

The IAU formerly classified Pluto as a planet, Ceres as a minor planet/asteroid, and Eris as a minor planet/trans-Neptunian object.

© 2005, 2006, 2008 by Wm. Robert Johnston.
Last modified 30 July 2008.
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