This is probably the single most requested feature.

I've yet to see the devs comment on it. Not a yes, not a no, nuffin'. (Maybe I'm just not looking in the right place for it, but I've been reading this and the Steam forum quite a lot over the last few months, and especially the last week or so...)

Still, it really ought to be automatic.

The game keeps track of which planets you've scanned, so we know it's keeping a record SOMEwhere. This wouldn't be a difficult feature to add, I'm sure.

I have noticed that when you visit a star system it appears faded in the map afterwards.  Also for the planets, if the name is underlined in yellow you have not scanned it.  If the line is green you have scanned it.

Note, I am on version 1.01.53103

Having the planets marked with different colored underlinings would be far more effective if you didn't need to be in close proximity to them to see said underlining. You can't hover over planets on the other side of the system to check their status.

We recently added a feature to the game where stars you have visited will look "faded" out and planets you have explored will have their orbit lines change to red. This will not apply retroactively to current saves though.

This was working good in my game with V1.01, but I am not seeing the faded stars with V1.02.