Caption:
Collage
to-scale insofar as that is known
of the 8 brightest
trans-Neptunian objects (TNOs):
Pluto,
Eris,
Makemake,
Haumea,
Sedna,
2007 OR_10,
Quaoar,
Orcus
and their known moons.
The Earth,
the Moon,
a linear scale to 2000 km are shown for comparison.
Features:
- The Earth,
Moon,
Pluto,
and Charon are
real images.
The others are artist's conceptions
since the astronomical objects
CANNOT be imaged.
- For the unimaged
astronomical objects,
their sizes are probably all estimated from their
H magnitude
and estimated albedos.
The 8 brightest
known TNOs are may
the 8 brightest ones of the
whole population of TNOs
since it is easiest to find the
brightest TNOs.
- Six
of the shown
TNOs
moons which
are also shown in the collage.
2007 OR_10
and Quaoar are currently estimated to be larger
than Sedna.
2002 MS4 (not shown) is,
to within uncertainty, estimated
to be larger than Orcus by Yoann Schmittling???,
but is less bright due to lower albedo.????
- Since Quaoar and
Orcus have
moons, it is known
from Newtonian physics that
Quaoar is much more massive than
Orcus.
- 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.
- 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.
- 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: Dwarf Planet:
Dwarf planets and possible dwarf planets).
We may well just call
former dwarf planets
large asteroids,
large TNOs, etc.
- See Trans-Neptunian object keywords
below
(local link /
general link: trans_neptunian_objects_keywords.html):
php require("/home/jeffery/public_html/astro/solar_system/trans_neptunian_objects_keywords.html");?>
Credit/Permission: ©
User:Lexicon,
2006 /
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.