trans-neptunian objects collage

    Caption: Collage to-scale insofar as that is known for 8 of the brightest trans-Neptunian objects (TNOs): Pluto, Eris, Makemake, Haumea, Sedna, Gonggong (AKA 2007_OR_10), Quaoar, Orcus and their known moons. The Earth also to-scale is shown for size comparison.

    Features:

    1. The Earth, Pluto, and Charon are real images. The others are artist's conceptions since the astronomical objects CANNOT be imaged.

    2. For the unimaged astronomical objects, their sizes are probably all estimated from their H magnitude and estimated albedos.

      Note the brightest TNOs are easiest to discover because they are brightest TNOs.

    3. Five of the shown TNOs have moons and these are also are also shown in the collage in artist's conception.

    4. Since Quaoar and Orcus have moons, it is known from Newtonian physics that Quaoar is much more massive than Orcus.

    5. The top 4 TNOs shown are accepted by the International Astronomical Union (IAU) as dwarf planets while the bottom 4 shown are dwarf-planet candidates that are accepted as dwarf planets by several astronomers (see Wikipedia: Dwarf planet: Population of dwarf planets).

    6. Eris (discovered 2005 Jan05 by Mike Brown (1965--) et al.) was the TNO that killed Pluto's planet status. It was clear that eventually we'd likely find more TNOs larger than Pluto and that if we left Pluto a planet, we'd soon have planets coming out of ears---and the whole class of planets would become degraded. The discovery of Eris made the problem palpable, and so Pluto had to go in the dwarf planet class.

    7. The dwarf planet class may NOT last. It's too hard to know what astronomical objects fall into it as evidenced by the long list of dwarf-planet candidates (see Wikipedia: List of possible dwarf planets). We may well just call former dwarf planets large asteroids, large TNOs, etc.

    8. See Trans-Neptunian object keywords below (local link / general link: trans_neptunian_objects_keywords.html):

        EOF

    Credit/Permission: © User:Lexicon, 2006, User:Aineias, 2015 / Creative Commons CC BY-SA 3.0.
    Image link: Wikipedia: File:EightTNOs.png.
    Local file: local link: trans_neptunian_objects_collage.html.
    File: Solar System file: trans_neptunian_objects_collage.html.