One thing I've always wondered is; why in English we have the same word for two meanings, both pronounced differently. For instance Live, wind, tire, lead.
As for the An union. I assume with the U, if you pronounce it as a phonic, udder, umbrella, ultrasonic, umbilical you use an. With others such as Ulysses, union, urinal, it's like it's being pronounced with a Y, so takes it's a consonant form of using A.
-An ultrasonic scan
-A Ulysses butterfly
As for the An union. I assume with the U, if you pronounce it as a phonic, udder, umbrella, ultrasonic, umbilical you use an. With others such as Ulysses, union, urinal, it's like it's being pronounced with a Y, so takes it's a consonant form of using A.
-An ultrasonic scan
-A Ulysses butterfly