Why does "an universe" sound so wrong? [closed]

I just ran across the phrase "an universe where" in a book, and my mind is telling me that it should be "a universe where." It just sounds wrong.

But... you're supposed to put "a" when the next word starts with a consonant, and "an" where the next word starts with a vowel. U is definitely a vowel. So why does this phrase sound so wrong?

Solution 1:

Although we are often taught that it is vowels and consonants that govern the ‘a’ or ‘an’ rule, it is actually the sound itself. That is, vowel sounds are preceded by 'an' and consonant sounds by ‘a’. In this case universe has a consonant (Y) sound.