Lyric discussion by Heavymetalharp 

Cover art for When Two Worlds Collide lyrics by Iron Maiden

Maiden's songs often have a sci-fi/horror/history/adventure theme to them. Sometimes they might just be about what they seem to be, sometimes there's a subtext or double-meaning (e.g. all the songs about "running on and on" or "marching on and on" that popped up after their massive Powerslave tour). This song, on the surface, is a sci-fi story about an large asteroid hitting the earth and causing destruction, but (according to Steve Harris in the first edition of the "Run to the Hills" book), Blaze (who wrote the lyrics) was probably also making a comment of how his previous life suddenly "collided" with the world of being in a major rock band when he joined Iron Maiden and was thrust in to the big league.

@Heavymetalharp That totally makes sense. It would have been a huge adjustment for Blaze... It was also a pretty intense/ dark time in the band's career with all sorts of personal things going on too... To be thrown into the situation would have been crazy!