Solar System: an unbelievably happenin' place

Impermanent features of the solar system are always a surprise to scientists, who assume everything here is so old that no impermanent features remain: the demeanor of the solar sytem is viewed as grand, stately, and slow.

Link is to an article about the rings of Neptune which seem to be falling apart before our eyes, and the scientists are dumbfounded and have no clue what to say about it.

What it means is, the features of the solar system have been inaccurately portrayed as old and permanent. But really it's a wild, chaotic, dynamic system, and don't assume nothin' ... shit flyin' everywhere ...