And we're 10 miles above Earth
in a starship.
The Big Bang Theory Season 4, Episode 24
♪ The Earth began to cool ♪
The Big Bang Theory Season 5, Episode 3
...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 Earth began to cool
The Big Bang Theory Season 7, Episode 24
Do you think there's a chance
that an asteroid could hit the Earth...
The Big Bang Theory Season 8, Episode 20