An interesting find in the outer solar system, the farthest known object
in our solar system, prematurely named as "Sedna". Probably under
1700 kilometers in diameter, this very red object orbits the Sun in an
orbit that takes it from 10 billion kilometers to 130 billion kilometers
from it. From outer part of the Edgeworth-Kuiper Belt to what the
finders want to call the "inner Oort cloud".

A very fascinating find, even if it´s probably too small to be called a
planet - but what is a planet? How do you define it? Well - that´s the
problem. Planets, asteroids, comets etc are all names and classes
invented by human beings; in nature the difference between planet,
asteroid and comet can be pretty much nonexistent. Pluto can be
called a planet, asteroid or Kuiper Belt Object(KBO) - some even call
it a huge comet.

So much wrangling about the definition of planet to come and much
shouting that Pluto isn´t a planet. But what if IAU - the International
Astronomical Union - takes away Pluto´s planet status and then
somebody finds an object in the outer solar system with Sedna-like
orbit that is larger than Mercury? Shall we then demote Mercury?

The fact is that the difference between Ceres, the largest of asteroids,
the bigger members of the Edgeworth-Kuiper Belt, Pluto and Sedna is
largely in the mind of human beings, who always want to classify things
and to be able to say: "That´s a planet, that´s an asteroid, that´s a
comet" and so on.