As already stated, there's no way of knowing until you return.
When I first set off I wished that there was a way of seeing what I'd made so far, but the further out I got the less it mattered and I'm glad you can't and hope it will remain that way. I feel it adds to the whole mystery and unknown to the exploring experience.
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Sorry.... misread the question... Doh!
Although again, as other have stated unfortunately not.
I keep a log through BPC, which a few updates back had an Exploration Log added to the Flight tab, I then make notes of anything I find of interest and record Earth-Likes, Water Worlds etc against the system they're discovered in.