The notes in the major scale are spaced in a funny way. Look at the white keys on the piano: some have black keys between them, other don’t. But you can understand the major scale using the circle of fifths. Start with C. Go up a fifth and you get G. Go up another fifth and you get D. Go up another and you get A. Go up another and you get E. Go up another and you get B. Go up another and you get F. And these are the notes in the C major scale!
This is a companion discussion topic for the original entry at https://johncarlosbaez.wordpress.com/2023/08/08/modes-part-6/