From what I understand of the Medicine Wheel, the celestial references are more like the cardinal points...North, South, East and West. The number 4 does seem to figure prominently in their way of breaking things down, and they seem to reference back to these four, plus up and down. These are the six directions one would smudge with sage, for instance, with an additional "up", making a total of seven directions.
I'm sure that stars and constellations play a part in their way of looking at things, but I haven't seen the Medicine Wheel itself connected directly to stars or constellations. More like directions and seasons. But you may know something I don't...
back to the astral elementally speaking! l did a medicine wheel workshop years ago where we had to visualise a journey to the underworld to meet the guardian [our own personalised one of course from our own imaginative stock of concepts], the drumming definitely evocative and enhancing the experience; heres the medicine wheel we used, yes cardinality again and the no.7 again!
14 spirit of animals
18 dharma 19 higher self
8 karma 9 life energy
10 measure of all
W 2 earth
12 planets 20 Wakan 15 souls of all E 1 sun
with life Tanka humans 11 stars
17 dream weavers 16 avatars
7 dreams 6 ancestors
S 3 plants
13 spirit of plants
7 dark arrows 7 white arrows
attachment / self awareness
dependencies/ self appreciation
judgement/ self acceptance
comparisons / self pleasure [life enhancing not indugence]
expectations/ self love
need for approval/ self actualisations
self importance/ impeccability [free from sins]