Parallax refers to the phenomenon in which there is apparent displacement in the position of an object that is viewed along two different lines of sight. Due to the phenomenon of parallax, the stars that are farther away seem to move very slowly compare to those that are near.
Many scales are diatonic including Major, Minor (the Harmonic minor is an exception) and modal scales. Examples of non-diatonic scale are pentatonic, octatonic and whole-tone scales.
