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It's near that planet. You know the one.

Uranus.

Ah, that's where it is. I guess I must've slingshot a bit too far around orbit. I thought that if I went to the Planet of the Apes, I'd find you.

Well, in the original Planet of the Apes movie and series there was an ape called Galen. True story.

Honestly, I tried to make a joke about a planet with your name on it. I basically Googled "planet galen", and I found the reference to the Planet of the Apes. That's the origins of how this joke began.