The objection of the stars alphabetical labeling is an non-issue. Astronomers remember it and like other "arbitrary" labeling schemas have mnemonics to help remember.
Oh Be A Fine Girl Kiss Me Right Now Smack
and for the academically challenged:
Oh Boy! Another Failing Grade Keeps Me Reconsidering Night School.


For absorption of light in water ( for scuba people)
Roy g. Biv Remember his name - red,orange,yellow,green,blue,indigo,violet

I won't tell you the mnemonic for the resistor color code since I've recently sworn off of uh swear words.
BBROYGBVGW