It's in a GALAXY far, far away.
The Big Bang Theory Season 2, Episode 21
...so that he could write an entry about Earth
for The Hitchhiker's Guide to the Galaxy.
The Big Bang Theory Season 8, Episode 8
The Milky Way is a GALAXY in space.
The Big Bang Theory Season 6, Episode 5
Wait. In The Hitchhikers Guide
to the Galaxy...
The Big Bang Theory Season 6, Episode 8
Which is also called
The Hitchhiker's Guide to the Galaxy.
The Big Bang Theory Season 8, Episode 8