I wouldn't use a hyphen, but (at least from the theory I've been studying) that's an example where the comma would differentiate coordinate adjectives (comma present: the planet is both bright and blue) from cumulative (comma absent: the planet is bright blue). So that's a case where I would not omit a coordinate comma. @thirdwind 's heavy metal detector is tricky. Assuming we're not doing the sensible thing and avoiding the phrasing... if the detector is both heavy and metal (coordinate adjectives), then I suppose it should be heavy, metal detector. And because they're coordinate, changing it to metal, heavy detector further reduces the ambiguity (but sounds weird IMO). If it's a metal detector that is heavy (adjective describing a compound noun), I'd probably hyphenate the compound noun: heavy metal-detector. Now I wonder why I feel so compelled to use coordinate adjectives only in a particular order. Does anyone else get that? Is there an explanation other than conditioning?
Boom, there it is! Google tells me there's a 'Royal Order of Adjectives' that goes something like: Opinion --> size --> age --> shape --> colour --> provenance --> construction --> noun The cumbersome, big, old, round, red, Tahitian, timber trapdoor. This fits with my subconscious usage patterns; anyone else?
So it was a good guess? Cool! And yes, they all work and feel strange rearranged. ie big old X feels right old big feels wrong. I am stoked that you found that page, as it had puzzled me in the past but never enough to seek out the reasoning. Very interesting to now see it, and it does make sense.
There is a similar concept that I cannot think of a good example of just now. I wanted to ask about it but cannot for the life of me remember an example so will post it later.
I think I usually punctuate, but if the adjectives are very short, I actually might leave it out. I stole her shiny, red Volvo. I stole her shiny red Volvo. But maybe that's actually not ok? Also, if there's already commas galore in the sentence (I do try to avoid too many embedded clauses), it's possible I'll leave it out, but then again... with a sentence like that, I'd probably avoid using more than one adjective. You do see them omitted in fiction, but I've never really examined those instances -- who knows, maybe it's been a grammatical choice instead of stylistic. My English professor about commas: "When in doubt, leave it out." My Finnish professor about commas (free translation): "Get them right or get out." I've figured out the rules with Finnish, but with English I'm sorta kinda just sprinkling them around.
Just wait till you get to the UK and have to spell diarrhea and hemorrhoids. Woopsy. Runs and piles, runs and piles....
When in doubt, leave it out? Yeah, I remember that one! In non-formal writing, I think the best thing is to write it the way you want (as regards commas) then come back to it a few days later and read it out loud. You'll know then if a comma is needed. I would certainly write "I stole her shiny red Volvo." When I did that kind of thing in a few places in my novel, some people objected. However, after putting commas in, as directed, I then went back and took most of them out again! They just seemed cumbersome. Correct, but cumbersome.
