Posted: 03.08.2005, 16:43
I blame Neptune.... If it didn't migrate out it wouldn't have ruined the orbits of the KBOs and they would have formed into the last planet! hehe
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https://celestiaproject.space/forum/viewtopic.php?f=7&t=7722
Michael Kilderry wrote:I think any solar system object with a diameter of more than 1000km ...
Scorpiove wrote:I blame Neptune....
Scorpiove wrote:I blame Neptune.... If it didn't migrate out it wouldn't have ruined the orbits of the KBOs and they would have formed into the last planet! hehe
Spaceman Spiff wrote:Michael Kilderry wrote:I think any solar system object with a diameter of more than 1000km ...
Hmm, yes, very metric of you! I wonder if someone would argue for imperial units (1,000 miles) with radius rather than diameter somehow, then both Pluto and 2003 UB313 wouldn't make planet status.
Michael Kilderry wrote:Might be best to use metric units though if we are going to use diameters and radius to decide whether something is a planet or not, as metric units are simpler and are becoming more common than the old imperial units.
Spaceman Spiff wrote:But, if the metre is based on the Earth's size, then can you say the 1,000km limit is any less arbitrary that 1,000 miles?
Spaceman Spiff wrote:Your list, while so colourful, is 'sizist'! At least, a planet 10 times the mass of Jupiter would actually be somewhat smaller than Jupiter...
Spaceman Spiff wrote:And why call Mercury a Marsian (Martian?) world, why not call Mars a Hermian world? Ah, details...
Michael Kilderry wrote:Spaceman Spiff wrote:But, if the metre is based on the Earth's size, then can you say the 1,000km limit is any less arbitrary that 1,000 miles?
The 1,000 km limit sounded like a good idea to me because it approximates to a 10th of the Earth's size, so everything is sort of rounded off that way. I'm not quite sure what you mean by the above statement.
Michael Kilderry wrote:Spaceman Spiff wrote:Your list, while so colourful, is 'sizist'! At least, a planet 10 times the mass of Jupiter would actually be somewhat smaller than Jupiter...
How much smaller? Smaller than Saturn? I thought they would be about the same size as Jupiter. My classification system would of course be "sizist" since size is what it's based on.
Michael Kilderry wrote:Spaceman Spiff wrote:And why call Mercury a Marsian (Martian?) world, why not call Mars a Hermian world? Ah, details...
Same reason why they call the new smaller exoplanetary discoveries Neptune-sized planets rather than Uranus-sized planets (if I'm not mistaken), Mars is more popular and well known than Mercury. But if you think this is unfair, we can call them "Mercur-martian" worlds. (I must have missed the "Martian spelling mistake in the last post).
Spaceman Spiff wrote: I wonder if someone would argue for imperial units (1,000 miles) with radius rather than diameter somehow, then both Pluto and 2003 UB313 wouldn't make planet status.
Spiff.
Spaceman Spiff wrote:So then, there's nothing special about 1,000,000 of our modern metres. Yet, choosing 1,000km as nice and round while at the same time letting Pluto into the (major) planet club, but rejecting Ceres, is to me 'sizist'! You favour one but not the other based upon an arbitrary size limit.
Planet X wrote:Hey, I should also point out that Brian Marsden of the Minor Planet Center (MPC) thinks that only bodies Mars sized or larger should be called planets. This means that if he had his way, our solar system would be down to just 7 planets! What a prick! Later!
Planet X wrote:Just so everyone knows right now, I DO NOT view asteroids and minor planets as the same thing. So, here goes our solar system's breakdown as I see it:
Giant Planet: 49000-143000 km in diameter: Jupiter, Saturn, Uranus, and Neptune
Terrestrial Planet: 6000-12800 km in diameter: Venus, Earth, and Mars
Minor Planet: 2000-6000 km in diameter: Mercury, Pluto, and 2003 UB313 (so far)
Asteroid/KBO: fist sized-2000 km in diameter: (All asteroids and KBO's)
Planet X wrote:Hey, I should also point out that Brian Marsden of the Minor Planet Center (MPC) thinks that only bodies Mars sized or larger should be called planets. This means that if he had his way, our solar system would be down to just 7 planets!