NavList:

How about:

Astronomers sat by their telescopes waiting for the selected body to reach apogee at their position, so they wanted to know how long they had to wait after the First Point of Aries passed.  Hence RA is measures eastwards in hours and minutes.  Like Frank says, Air Navigators particularly didn’t have time for all that messing around.  They just wanted something to add onto LHA Aries to get LHA Star for a convenient time.  Hence SHA is measured in degrees west of Aries.  It’s as if RA convention allies itself with time to reach a particular position in the sky, whereas SHA convention allies itself with position in the sky at a particular time.  DaveP