Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is... |
Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is... |
Aug 14 2006, 06:06 AM
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Member Group: Members Posts: 295 Joined: 2-March 04 From: Central California Member No.: 45 |
-------------------- Eric P / MizarKey
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Aug 16 2006, 01:37 PM
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#2
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
I must admit - I was explaining all this to my ever fascinated colleague Josh ( for those that watch QI I said "How many planets are there Josh" "Nice?" "BZZZZZZZZZ -awooga...awoooga" ) and we debated the point of Charon getting an upgrade.
Why should the movement of the barycenter from 1m below the mean radius to 1m above reclassify the system from being planet + moon to being binary? Systems evolve, that reclassification could occur during the lifetime of a system, and I don't think a body should be reclassified from moon to planet just because it got a little further away. A body is what a body is....it doesnt matter where it is (as the rest of these new rules would have us believe)...and I think it makes a bit of a farce of the system if suddently we have to go back to our text books because a system has evolved and scrub out 'moons...1' and instead right "binary planet" BUT....then...there ARE likely to be binary systems out there, so at what point do you say "ok - this is now a binary system, not planet+moon" - mass, radius, etc etc....you do need a cut off, but I don't think it should be one that can change. Doug |
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Aug 16 2006, 01:49 PM
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#3
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Member Group: Members Posts: 809 Joined: 11-March 04 Member No.: 56 |
Systems evolve, that reclassification could occur during the lifetime of a system, and I don't think a body should be reclassified from moon to planet just because it got a little further away. I'm just imagining: 1) A "lumpy" primary (shaped something like Iapetus) where the barycentre is sometimes below the actual surface and sometimes above it 2) An ellipsoidal primary, where the barycentre is sometimes below the actual or notional surface of the ellipsoid and sometimes above it 3) A primary with a thick atmosphere, where the barycentre is suspended somewhere "in the middle of the air" 4) A primary with an atmosphere whose height changes seasonally, so that the barycentre is sometimes in the atmosphere and sometimes in space You can have all sorts of fun with this, the more so if you happen to live on such a world. "Is that the Moon?" "No, it's a planet... today..." |
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