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Errantry: Novak's Journal
...Words to cast/My feelings into sculpted thoughts/To make some wisdom last
Random: On Revoking Pluto's Status as a Planet/Murder 
24th-Aug-2006 07:25 pm
Sitting Duck/Art of Michael Bedard
I have to say that I'm glad that this didn't happen whilst Clyde Tombaugh, one of my childhood heroes, was still alive: it would bite to have spent your life as the discoverer of the 9th planet only to have it revoked during your golden years.

Also, has anyone noticed that the third part of the new definition of a planet, that part which solely disqualifies Pluto – that the designated planet "has cleared the neighbourhood around its orbit" (and which seems somewhat arguable to me as it seems fuzzy regarding double planet systems or assumes all stellar systems to be as "clean" as ours) – absolutely invites Pluto to destroy Neptune and thus regain planetary status? Is this the kind of behaviour we want to reward in our solar system? Is it?!
Comments 
25th-Aug-2006 02:25 am (UTC) - behavior
I would give that a resounding no, as I think we are rewarding enough bad behavior right here on earth.
25th-Aug-2006 03:36 am (UTC) - Re: behavior
Now is the time to journey home to tell of what I've learned
My people I believe have every right to be concerned
For in spite of computers and advanced psychology
Behavior patterns are still a mystery
I predict the future of this earthly human race
Is that having made a mess of Earth
They'll move to outer space

Well, there goes the neighborhood....
– Leonard Nimoy, "Highly Illogical"
25th-Aug-2006 12:00 pm (UTC)
A double planet system, if it violated another planets orbit, would then not be a double planet system but a double dwarf-planet system. If it's a true double planet system, then they would be two planets because the centre of gravity would be outwith the radius of either (hence one is not a satellite of the other).

The reason something that breaks something else's orbit (as Pluto does) is not a true planet is because that means it did not form from the primordial solar system debris as the others did, rather it was captured later. I suppose this could also happen from a very large impact too though, so there could be rare cases of true planets violating orbits. But not in our solar system, anyway. Pluto is a captured object.
25th-Aug-2006 12:13 pm (UTC)
Do you think that all naturally-forming planets in a star system would necessarily form in an eccliptic plane? That was one thought I had in the smaller, serious part of that entry. I could imagine a much more chaotic star system with a variety of eccentric orbits.
25th-Aug-2006 03:29 pm (UTC)
I don't think you could have any outwith the ecliptic, because it is gravity that causes the solar system to form fom the dust. The gravity starts it all spinning, and as it spins, in flattens into a disc (which is the plane of the ecliptic) and out of the disc the sun, then the planets, form. The rocky (terrestrial) planets are nearer the sun because at that distance the volatile gases such as hydrogen and helium couldn't freeze and attach to them, and the gas giants are further out because there the lighter elements were able to condense and coalesce into giant gaseous bodies. Thus I don't think gravity would allow planets to form outwith the ecliptic.

You can also therefore see another reason why Pluto is an anomaly - it is a rocky planet, but it is out past the gas giants - another indication that it didn't form from the early solar system like the others.

What you are left with after the planets have formed is a lot of rock and dust that didn't become planets for various reasons, like the Kuiper Belt, and the asteroid belt between the terrestrial planets and the gas giants.
25th-Aug-2006 07:22 pm (UTC)
Ah, right: I'd not been connecting the ecliptic to the whole dust-disc, planet-formation business in my mind. Thanks for clarifying that.

Do you think that the definitions work? In particular, I'm wondering whether you think that stellar systems could form rocky outer planets that do take on full global form, and perhaps even are larger than inner rocky planets, and settle into stable orbits even if there is a lot of Kuiper-style junk around? Or in other words, do you think that late formation as you've described it is really planet-defining or is size/shape more important?
25th-Aug-2006 06:28 pm (UTC)
I find the whole thing a little weird because I grew up with 9 planets, and one always assumed that if anything changed, they'd discover more, not discover that in fact there were only 8.

However, the night before the decision, I read an obnoxious post in a friend of a friend's journal comparing the whole 10th planet thing to same sex marriage. It was an analogy about how previously we narrowmindedly thought that things were not planets, but now that we know more we realize there are in fact 10 or 12 or 14 objects in our solar system that can be considered planets. The post also took some swipes at Christianity. So, when I heard about the Pluto decision, I remembered this post and thought it was an interesting theological turn about - upon closer examination, some of the deeply held views of the 20th century turned out to be wrong but it is not too late to abandon them and move forward.

If you try hard enough, you can find theology in everything. :)
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