Space Rocks
That title is, of course, a play on words. Just like every other kid who grew up in the Space Age, I have always found space to be rather cool. Watching astronauts walk on the moon is one of my earliest memories, in fact. But if that's truly what I was imparting here -- just an enthusiasm for mankind's forays into the void -- it would have been exclamatory: "Space Rocks!" Instead, it has a more literal meaning, without any verb implied. Because space isn't exactly "full" of rocks wheeling around out there, but there are enough of them that one of them could threaten Earth at some future point. If the space rock was big enough, it could even cause an "extinction-level event," much like the impact which wiped out the dinosaurs. There's even a whole movie genre devoted to the problem: from the 1950s When Worlds Collide to the more-modern Deep Impact and Armageddon to the more recent (and much more cynical) Don't Look Up.