Thinking on Planets -- Size Matters!
As I read more and more on the definition of a planet, I see more arguing and debate. Mostly over the status of Charon, Ganymede, our moon etc.
I just have to give my opinion on how I, as non-professional would do it. I know I am not qualified to do this but it's my blog where I say what I think.
I like the idea of having enough mass to become nearly a sphere, in fact I would make that the prime criteria along with mass being below the point of deuterium fusion (being large enough for that would make the object a brown dwarf.)
What I would change is I would adjectives to clarify things.
Primary Planet: Meets mass criteria and orbits a star, brown dwarf, or stellar remnant.
Secondary Planet: Meets mass criteria and orbits another planet.
Rogue Planet: Meets mass criteria but does not orbit a star.
Secondly I would have a series of at least five adjectives giving a succession of sizes. The actual numbers are arbitrary and scientists would know better than I on where to draw the lines.
Minor Planet: Less than 1000KM in diameter
Small Planet: 1000-<4000KM in diameter.
Midrange Planet:4000-<20000KM in diameter
Large Planet:20000-<50000KM in diameter
Giant Planet:>50000KM in diameter.
Thus Earth would be a Midrange Primary Planet while the moon would be a Small Secondary Planet. Ceres would be a Minor Primary Planet.
Of course as our knowledge grows, other terms would be needed to describe the planets temperature, composition and origin.
I just have to give my opinion on how I, as non-professional would do it. I know I am not qualified to do this but it's my blog where I say what I think.
I like the idea of having enough mass to become nearly a sphere, in fact I would make that the prime criteria along with mass being below the point of deuterium fusion (being large enough for that would make the object a brown dwarf.)
What I would change is I would adjectives to clarify things.
Primary Planet: Meets mass criteria and orbits a star, brown dwarf, or stellar remnant.
Secondary Planet: Meets mass criteria and orbits another planet.
Rogue Planet: Meets mass criteria but does not orbit a star.
Secondly I would have a series of at least five adjectives giving a succession of sizes. The actual numbers are arbitrary and scientists would know better than I on where to draw the lines.
Minor Planet: Less than 1000KM in diameter
Small Planet: 1000-<4000KM in diameter.
Midrange Planet:4000-<20000KM in diameter
Large Planet:20000-<50000KM in diameter
Giant Planet:>50000KM in diameter.
Thus Earth would be a Midrange Primary Planet while the moon would be a Small Secondary Planet. Ceres would be a Minor Primary Planet.
Of course as our knowledge grows, other terms would be needed to describe the planets temperature, composition and origin.
posted by shoprat at 12:27 PM
5 Comments:
Personally, I think I should have my own planet! After all, I'm good enough, smart enough, and gosh darn it, people like me! (Apologies to Stewart smalley).
Makes me wanna go out and buy a telescope. :)
This stuff is pretty cool.
What is your opinion on using orbits as criteria?
lp A primary planet would need to be the dominant object in its orbit so again that throughs Ceres into a question.
Oh man ... it's a good thing I'm getting to the age where I don't have to re-learn all these new up and coming planets. Now where's that telescope so we can have a look at these new cool rocks.
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