[X] My Assistant

[ilbasso]

Seeing that you knew Charon's name when you were a kid makes some of us feel mighty old - it doesn't seem THAT long ago that we didn't know that Pluto had a moon!

If I REALLY want to make myself feel old, I can remind myself that I visited Hawaii before it became a US State! On the way from Japan (where I was born) to the US, our ship stopped in Honolulu in June 1957.

[Patteroast]

If you feel old, I feel like a newborn... the first moons I remember being discovered are Caliban and Sycorax in 1997. I was alive for the Neptune tour in '89 and Pan in '90, but considering I was 2-3 years old, I don't quite remember them.

Personally, I don't think it's silly to ask a definition of planet. Sure it's a wide category, but I think we're stuck with it now, whether we like it or not. I don't think any dictionary editors will be fazed even by the IAU calling them up and telling them what a planet is.

When I took my high school astronomy classes, there wasn't much about the moons at all. When we took notes, maybe one little note about each of the Galileans and Titan. And that was about it. I was quite disappointed, although at that point I didn't expect I'd learn anything new.

As for being able to name the planets and moons, I still pride myself on it. Well, more on the moons, since there are so many of them nowadays. And speaking of which, the issue of what's a moon is still open, too... unless someone wants to catelog each and every ring particle out there as one.

[JRehling]

When I took my high school astronomy classes, there wasn't much about the moons at all. When we took notes, maybe one little note about each of the Galileans and Titan. And that was about it.

Considering this post and Emily's earlier, I am starting to think that a lot of angst over the "planet" label might be eased if someone issued an "authoritative" list of the Ten Most Interesting Worlds, to keep people from mistaking the label "planet" with "most interesting". Of course, this would still be political as hell, and people would argue about what number to stop at, but at least it would keep people from assuming that what's not a planet isn't interesting. The point would be more of an educational canon -- nothing scientific.

I'd say that a good solar system education should pay special attention to these worlds: Earth, Sun, Moon, plus a topic each for Venus, Mars, Jupiter, Saturn (rings), Uranus/Neptune, Pluto/KBOs, Io, Europa, Titan, asteroids/comets/small satellites. That covers just about everything in ten topics.

[Gsnorgathon]

Maybe that's the solution to the "planet" problem. Let's just call 'em all "worlds".

A "ten most interesting worlds" poll might be kind of fun...

...but I've already thought of a quandrary: I think Saturn's rings are awfully cool, but find Saturn itself rather boring. Do rings count as part of a planet, or are they a "world" in themselves? Or worlds?

I do apologise for drifting off the TNO topic. Maybe we need a "what's a world? / what's a planet?" thread.

[alan]

How about if the body is large enough to have tectonics or volcanisms we call it a planetary body. That brings in Enceladus, Miranda and Vesta.

[chris]

How about if the body is large enough to have tectonics or volcanisms we call it a planetary body. That brings in Enceladus, Miranda and Vesta.

And Triton. Don't forget the liquid nitrogen geysers....

Chris

[djellison]

I dont think you can judge a body on it's nature, only it's 'stats'

At some point - you're always going to have to make an discreet cut-off, be it size or some other parameter.

I thinn the phrase 'planet' should be reserved for anything that orbits the sun and is over X km. Anything that orbits a planet is a moon. Anything smaller than X is a minor planet.

[SFJCody]

I dont think you can judge a body on it's nature, only it's 'stats'

At some point - you're always going to have to make an discreet cut-off, be it size or some other parameter.

I'm in favour of semi-arbitrary cut-offs, but I think it should be mass rather than diameter, just like the present upper limit (13 Mjup). Planetary satellites could be called 'secondary planets' and be categorized in exactly the same way

How about:

'World' planets (bodies containing less than 5% molecular hydrogen):

0 < m <Mmimas = minor planets (takes out most of the aspheroidal bodies)
Mmimas < m < Mmercury = dwarf planets/small planets/mesoplanets/planetoids
Mmercury < m < 5 MEarth = major planet
5MEarth < m = super planet (none known to exist)

I think there should be a separate classification for objects composed of between 5% and 50% molecular hydrogen. Uranian planets? Ice giants? I don't think they belong with the Jovians or with the 'world' planets.

Jupiter and Saturn are different again. Gas giants, Jovians, call 'em what you will. I see them as the dwarf end of a range that has stellar bodies at the upper end, not as giant versions of bodies like Mercury.

Bodies with > 50% hydrogen

? < m < 13 Mjup = jovians
13 Mjup < m < 90Mjup = brown dwarfs

Should be some </= signs rather than < signs here, but you get the idea...

[SFJCody]

Another insight into the forthcoming IAU decision:

http://www.sfgate.com/cgi-bin/article.cgi?...MNGU5E4K2Q1.DTL

Jill Tarter: "In the fine old astronomical tradition, (Pluto) will probably remain a planet, but I don't think we need to repeat the error with Mike Brown's newest discovery, even if it is bigger than Pluto."

Don't like this idea at all. Yes, the label 'planet' is in common usage, but that isn't a good reason to continue propogating it (especially if it becomes as meaningless as this proposal would make it). It's a sign that there is a major barrier between the public and the astronomical community; one that needs to be broken. To do otherwise is patronising and carries the assumption that people are too stupid to understand more a short list of the names of ancient gods.

I think culture would appreciate the word 'world' more than 'planet' or 'moon' anyway. Which sounds more funding-worthy:

A mission to 'Saturn's biggest moon, named Titan'
or
A mission to 'a world named Titan'?

'Planet' belongs in the era of naked-eye to telescopic astronomy. It's a name for bright lights in the sky that change position relative to the crystal vault of the heavens.

It's not a name for places that humans drive remotely controlled vehicles across the surface of.

[ljk4-1]

How about Tombaugh?

[alan]

Maybe the list of planets won't get so crowded after all. Some of the brighter KBO's may not be as large as has been assumed. Instead they only have a brighter surface.
Albedos, Diameters (and a Density) of Kuiper Belt and Centaur Objects

[SFJCody]

Several updates at:

http://www.gps.caltech.edu/~mbrown/planetlila/index.html

Nat Geo article:

http://news.nationalgeographic.com/news/20...w_planet_2.html

Back to the Drawing Board

As of yesterday, you and I know as much about 2003 UB313's name as the planetoid's discoverer does.

Brown's suggested name was made under the guidelines for naming a small body, which don't specify a preferred cultural origin.

"But I just heard from the IAU that, if they rule that it's a planet, they want to go with a Greco-Roman name [along the lines of 'Saturn,' 'Jupiter,' and 'Mars']," Brown said, "which is not at all what I suggested."

Also:

Spitzer observations of 2003 UB313 on 25 & 26 August.

2003 UB313 currently listed as H = -1.1 (data-arc = 1954-2005)
2005 FY9 currently listed as H = -0.2 (data-arc = 1955-2005)
2003 EL61 currently listed as H = 0.1 (data-arc = 1955-2005)

[TheChemist]

It seems almost certain to me now that if it is recognized as a planet, it will be a feminine name probably between Persephone/Artemis/Minerva.

[Rob Pinnegar]

It seems almost certain to me now that if it is recognized as a planet, it will be a feminine name probably between Persephone/Artemis/Minerva.

Personally, my vote's for "Yuggoth". Fans of H.P.Lovecraft will understand.

[ljk4-1]

Personally, my vote's for "Yuggoth". Fans of H.P.Lovecraft will understand.

ALF once had names for the two planets beyond Pluto. They were something like Dave and Steve. Anyone remember? Or care to admit they know?