So it's a thing that isn't self illuminated (not a star) that revolves around a star but is bigger than an asteroid or comet. Which is one of those loosly worded definitions that just causes problems down the track, with a lot of wiggle room to argue.

Some astronomers think Pluto is just one of many similar objects in the Kupier belt and not really a planet. Other astronomers want as many as 15 objects classified as planets (and more again in the future as they're discovered and they wish to approach immortality by stitching their name to a planet).

Currently, the cut-and-dry approach is to adopt the standards of the International Astronomical Union, which lists the ones you learnt at school from Mercury to Pluto. It classifies objects orbiting the sun as minor planets, major planets, asteroids, comets and trans-Neptunian objects.

Orcus, Ixion, 2002 UX25, Varuna, 2002 TX300, 1996 TO66, 2003 EL61,Quaoar, 2005 FY9, 2002 AW197, 2002 TC302, 2003 UB313 and Sedna are things in orbit, the size of Pluto or larger which do not enjoy planetary status and the perks of being rote-learned by small children that it conveys.

Sedna is a bit odd, and further out. It's (usually) considered part of the Oort cloud, which is roughly one light year away - or one quarter the way to the nearest star to the sun.

The IAU is moving toward this definition: "A planet is a body that directly orbits a star, is large enough to be round because of self gravity, and is not so large that it triggers nuclear fusion in its interior." which neatly keeps Jupiter as a planet (it emits more heat than it gets from the sun, but isn't quite large enough to compress under it's own gravity enough to turn into a star - it needs to be about 70x bigger for that).

So, the final answer:

An acceptable name would probably be greek, latin or old-english in origin (eorthe->erthe->Earth, the latin was Terra or Tellus, Gaia in Greek), simply to be in keeping with the rest of them (at least for english speaking astronomers) - though they'll run out of infernals shortly.

It's a planet because the men in white coats who study such things tell us it is so. And we accept without question because they're the ones in white coats, and just perhaps they have access to those straight jackets and we don't like those. Currently Pluto is one. If they adopt the definition above, Pluto will keep it's status. There are others on the table which would definitely deregister Pluto.

Next question will not be "how long is a peice of string?"

Follow up Q/A

I always thought Persephone(G)/Persipina(R) would have been better for Pluto's moon, Charon (though, again, it would be odd to have the spring goddess locked in a frozen embrace). Charon would be better suited for something inside the Kupier belt, floating in the river of forgotten near-planets, like UB2003-313, the one the original question was about. But that's all named now, with no thought of consulting me on it, so we just have to make the best of it.

Thanatos (Death), Pontus (Deep sea) and Nix (Night) would be the front running names for me, in roughly that order.

As for the Norse, they already have the Sun (which is larger than all the other stuff in the solar system combined), and as an additional bonus, days of the week.


Sunna day - English "Sun" is from the norse "Sunna"
Mani's day - The Norse name for the Moon is Mani
Tyr's day - Anglified into Tues.
Oden's day - but Oden was also know as Woden, so it was Wodensday.
Thors's day
Freya's day

Saturn's day is the only greek-inspired day of the week.