I think by interstellar they mean beyond the heliopause [1] and hence “between stars”. [1]: https://en.wikipedia.org/wiki/Heliosphere#Heliopause https://en.wik

I think by interstellar they mean beyond the heliopause [1] and hence “between stars”. [1]: https://en.wikipedia.org/wiki/Heliosphere#Heliopause https://en.wikipedia.org/wiki/Heliosphere#Heliopause