These are all very nice. My friend really loved 21. :)
20 and 21 - I like them - but they are reminscent of a company I had in the 90s which I ended up not being too happy with. The irregularly shaped bubbles is what reminds me. I like the layout of #21 though.
#18 - not that I want literal, but this suggests a supernova to me, not a constellation. Neat, but not what I'm going for.
#19 - I like the compass like feel of this, as constellations are used for guidance. This one is neat. I also like feelings of motion in designs, perhaps some dimensionality. Maybe more playing with the name itself.
I like #123, but am not fond of the click-art stars used. Could you try a 4-pointed star? Someone else used some nice ones in another logo that were 4 pointed...thx!