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 smaller satellites Hydra, Nix, and S/2011 (134340) 1;
• (136199) Eris and its satellite Dysnomia;
• (136108) Haumea and its satellites Hi'iaka and Namaka;
• (136472) Makemake;
• the distant object (90377) Sedna;
• the other known trans-Neptunian objects that are at least 600 km in diameter;
• the triple object (47171) 1999 TC36; and
• the U.S. state of Texas for comparison.

Relative sizes, brightnesses, and colors are shown.

As of 2012, the IAU classifications for these objects include:

• planet: Earth, Mercury
• dwarf planet: Pluto, Ceres, Eris, Makemake, Haumea; 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, (4) Vesta, and (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, S/2011 (134340) 1, Dysnomia, Hi'iaka, Namaka (satellites of dwarf planets), and 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.

© 2005-2009, 2012 by Wm. Robert Johnston.
Last modified 29 April 2012.
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