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IAmNorRealTakeYourMeds@lemmy.world 3 weeks agoI’d rather we have dozens of planets, with news articles talking about “new planets discovered”
we can still teach the handful of “classical planets”, so we can have posters, or have like periodic tables, and everyone be aware that they might go out of date as more is discovery.
the solar system will be more exciting and more varied.
also, the “clearing orbit from similar objects” is time and orbit dependent,
larger orbits take longer to clear, which mean in a few billion years ceres might eject pluto and become a planet?
or we could have gas giants beyond pluto (like this hypothetical 9th planet ) which it would be unlikely it has cleared its orbit, so we could have a planet larger than Jupiter which we would call a planet, but if we discover another planet in its orbit (too large to clear), then we will have to say that it is a dwarf planet.
squaresinger@lemmy.world 3 weeks ago
The main issue here is that everything from a speck of dust to the massive black hole at the centre of the galaxis is pretty much the same thing on a large spectrum.
You can clearly say that some grains of dust are something entirely different than a supermassive black hole, but it’s really hard to find solid cut-off points to categorize anything in between.
So we started with a handful of arbitrary examples for each category, which was easy when we only had these examples, but with more and more discoveries the gaps between these examples are filled and it becomes a spectrum, and then it becomes iffy what exactly fits into which category.
IAmNorRealTakeYourMeds@lemmy.world 3 weeks ago
I get all that, and maybe a size threshold would have been useful.
but the rule of “cleared its own orbit” is not only arbitrary, but time and orbit dependent.
you there could be another planet far away, which is likely a gas giant, and if discovered it would be obviously considered a planet. however we will never know for sure because we will never know if there’s another object in it’s orbit, and if we then discover another gas giant in its orbit (it would be so large it’s unlikely to have cleared its orbit), then we would have to demote two gas giants (or more) into a dwarf planet status.
which is so plainly ridiculous. just make a reasonable threshold between asteroid and planet based on mass. or even geology, if it’s just loosely bound rubble, its an astoroid, if it’s large enough to have geology of some sort, then a planet (although that would be harder to determine).
but just based on an extrinsic factor?
if eventually Ceres yeets pluto out, would Ceres become a legit planet?
why is a planetary object multiple AU away from the object you are studying determined wether something is a planet or a dwarf planet?
that’s like defining that hydrogen is no longer hydrogen if it is bound with another element.
squaresinger@lemmy.world 3 weeks ago
I totally get your point.
I think the rule of “cleared its own orbit” tried to be less arbitrary and failed horribly.
A size threshold is clearly more consistent, but it’s purely arbitrary, while the “cleared its own orbit” rule at least has the appearence of not being totally arbitrary, even though it introduces just the problem you are describing.
IAmNorRealTakeYourMeds@lemmy.world 3 weeks ago
it’s fine to place arbitrary separations in a spectrum as long as we are aware it’s a spectrum.
but it’s also annoying that “dwarf” implies smaller, and as I said before, we could have gas giants that could be classified as a dwarf planets.
and without a doubt there are exoplanets that are gas giants but also dwarf.
which is just plain stupid.