I always thought a green fireball was neat due to the color and brightness. Now I know it’s due to the magnesium. Cool.
I thought a green one was nickel and a blue one was magnesium, but I’m no expert and have only seen a few examples with distinct coloration. The blue one was odd, from my vantage point it appeared to come straight down. UNC lost a big basketball game that night, so it led to some amusing comments about symbolizing Carolina’s basketball season.