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Post by general313 on Apr 22, 2018 18:05:39 GMT
Astronomers spend a lot of time classifying planets into regular planets and dwarf planets, and coming up with precise definitions of each (thus arguing that Pluto is not a regular planet). They do no such thing for moons (aka satellites) and happily declare that Saturn has 62 confirmed moons, the smallest of which is possibly only 40 meters in diameter. It's almost as if someone threw out a baseball and it went into orbit around a planet it would get accepted as a new moon. Why the inconsistency? I'm not arguing against having size criteria for planets, just for having them for moons.
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Post by marsexplorer on Apr 22, 2018 23:41:29 GMT
general313 A planet is a body that orbits the Sun and clears all the debris in it's path. Pluto, Ceres and the other dwarf planets don't clear their path. You must make that distinction otherwise asteroids and comets that orbit the Sun would need to be classified as planets also. A moon is a natural body that orbits a planet. A baseball or anything else that humans put in orbit is not a natural object. While I didn't like it when Pluto was demoted to a dwarf planet, I can understand why it was.
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Post by MCDemuth on Apr 23, 2018 0:13:58 GMT
So what you guys are saying is... Any day now, the Earth could acquire a second (or more) moon(s)... When a baseball sized meteor is captured by Earth's gravity, and it goes into orbit? If so, maybe we already have more than one moon, and we just don't know it yet!  |
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Post by general313 on Apr 23, 2018 14:45:03 GMT
general313 A planet is a body that orbits the Sun and clears all the debris in it's path. Pluto, Ceres and the other dwarf planets don't clear their path. You must make that distinction otherwise asteroids and comets that orbit the Sun would need to be classified as planets also. A moon is a natural body that orbits a planet. A baseball or anything else that humans put in orbit is not a natural object. While I didn't like it when Pluto was demoted to a dwarf planet, I can understand why it was. Yes, as I said in my OP, I'm not contesting the classification of planets, just the inconsistency with moons. Isn't there a risk of objects in Saturn's rings getting classified as moons without a size cutoff? Is there a size cutoff for a moon? Or is a rock with the same mass as a baseball good to be a moon? |
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Post by MCDemuth on Apr 23, 2018 16:21:50 GMT
just the inconsistency with moons. Isn't there a risk of objects in Saturn's rings getting classified as moons without a size cutoff? Is there a size cutoff for a moon? Or is a rock with the same mass as a baseball good to be a moon? I think you 'almost' brought up another good question... When does a rock get classified as a moon, or as a ring? If we are talking about baseball sized rocks and larger, I think Saturn's rings are full of them... Does this mean that we should count every one in the rings as moons? If so, Saturn could have something like, 1 million moons! LOL! How about we rename Saturn's rings. How does "Moon Rings" sound? or would it be confusing with "Mood Rings"? But that works too, since some people say that a Full Moon affects how people people behave. "Moody Moon Rings"? LOL! Sorry... |
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Post by general313 on Apr 23, 2018 17:03:34 GMT
just the inconsistency with moons. Isn't there a risk of objects in Saturn's rings getting classified as moons without a size cutoff? Is there a size cutoff for a moon? Or is a rock with the same mass as a baseball good to be a moon? I think you 'almost' brought up another good question... When does a rock get classified as a moon, or as a ring? If we are talking about baseball sized rocks and larger, I think Saturn's rings are full of them... Does this mean that we should count every one in the rings as moons? If so, Saturn could have something like, 1 million moons! LOL! How about we rename Saturn's rings. How does "Moon Rings" sound? or would it be confusing with "Mood Rings"? But that works too, since some people say that a Full Moon affects how people people behave. "Moody Moon Rings"? LOL! Sorry...I almost brought up another good question? That's been my point all along: why is there no size criteria for moons. But not to get hung up in semantics...  In any case, the argument has been made that a size criterion for planets is necessary so that we don't have hundreds or thousands of asteroids going on the planets list. How is that any different than the situation with Saturn and the debris found in Saturn's rings? |
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