interstellar travel
Technical term used in astronomy, space exploration, and science fiction. Refers to travel between stars.
Interstellar travel has not yet been realized, but much research is underway.
宇宙旅行 is a broader term for space travel in general, including orbital or lunar trips, while 恒星間航行 specifically means travel between stars.
Compound of 恒星 (fixed star) + 間 (between) + 航行 (navigation, sailing). The term is a modern coinage for interstellar travel.