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 moon of Neptune;
• Pluto, its large moon Charon, and its smaller moons Hydra, Nix, Kerberos and Styx;
• (136199) Eris and its moon Dysnomia;
• (136108) Haumea and its moon Hi'iaka and Namaka;
• (136472) Makemake;
• the distant object (90377) Sedna;
• the 46 other known trans-Neptunian objects that are at least 500 km in diameter--at least as large as the three largest asteroids--and their 7 known moons;
• the ringed object (10199) Chariklo;
• the triple object (47171) 1999 TC36; and
• the U.S. state of Texas for comparison.

Relative sizes, brightnesses, and colors are shown.

As of 2015, 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 moons of planets), Charon, Hydra, Nix, Kerberos, Styx, Dysnomia, Hi'iaka, Namaka (moons of dwarf planets), and moons/components of other trans-Neptunian object systems

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

© 2005-2012, 2015 by Wm. Robert Johnston.
Last modified 19 July 2015.
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