The name instantly conjures the flute melody.
A wonderful piece of science fiction.
@thatsnothowyoudoit @Madison_rogue
Pennywhistle is easy to play though I haven't done so in ages. This is the whistle(in D) used in the episode...
http://www.thewhistleshop.com/catalog/whistles/inexpensive/oak/oak.htm
Music here...
https://musescore.com/uketrek/inner-light-transcription
I'm not enough of a musician to vet the accuracy of the transcription, but it should be good. Any whistle in D will work, but the Oak is the one played in the episode.