Listen closely to the scanner sound. You can hear how long it's taking to finish to scan.
That would certainly be useful, but probably won't be possible: I remember having seen a developer quote where he said that many of these data aren't stored and hence not available. (If you think about it, that's reasonable: for instance, the list of visited stars for all playerswould balloon quickly to enormous sizes.)
but the data is stored. When i visit stars i can see who discovered is it says the discoverers name right on the info of the body in the system map? maybe i misunderstand?