It's typical of Elite design; slow, pointless, and gets weirder the longer you dwell on it; though at first it looks like it's got a real purpose.
Yes it's Bitterday. >_____>
It's probably a leftover from some early design plan. It lowers when your leaving. but is raised when landing.
kind of looks cool so they've kept it. So as part of the ship launch sequence it's fine, use the time to set next destination.
Oh yea! and don't think about it too much