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) Haumea (=2003 EL61) with its two satellites Hi'iaka and Namaka, and (136472) Makemake (=2005 FY9);
• the distant object (90377) Sedna;
• the other known trans-Neptunian objects that are at least 600 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, (50000) Quaoar, (55636) 2002 TX300, (90377) Sedna, (90482) Orcus,
  • 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, Hi'iaka, Namaka (satellites of dwarf planets), and unnamed satellites of (47171) 1999 TC36, (50000) Quaoar, (90482) Orcus, and (208996) 2003 AZ84 (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.

© 2005-2008, 2009 by Wm. Robert Johnston.
Last modified 21 May 2009.
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