Hmm. Indeed.What's confusing about that?
That the trailer makes it look like a prequel to Alien.
I actually wasn't paying close enough attention the first time. It does look at awful lot like a prequel to Alien. That big thing outside looks just like the space jockey ship. Hell, even the way the title "Prometheus" appears on the screen is exactly like "Alien" appeared on the screen in the first movie.
Either way, I'm intrigued.
Ofcourse its an Alien prequel, its got the "Space Jockey" in it for christs sake!