Imagine you're a green alien living happily among other green aliens on a tiny planet somewhere. Then one day an astronaut from Earth shows up and starts terrifying everyone. And he has the voice of Dwayne "The Rock" Johnson! Except maybe contractual stipulations demand that he not be called "The Rock" anymore. Still! Scary!

That's the premise of Planet 51, a computer-animated comedy that has finally, after some shuffling, been acquired by Sony and scheduled for a Thanksgiving 2009 release. The voice cast includes Johnson, Gary Oldman, Justin Long, Seann William Scott, John Cleese, and Jessica Biel. The directors are a trio of video game programmers named Jorge Blanco, Javier Abad, and Marcos Martinez, and the script is by Joe Stillman, who co-wrote the first two Shrek films.

As we reported last November, Planet 51 was originally picked up by New Line and would have been that studio's first CG release. Then New Line was folded into Warner Bros., so the film became that studio's property, and they planned to release it next summer. But according to Variety, Planet 51's producers wanted it to come out this November instead -- and that didn't work for Warners because they're already releasing a Harry Potter film in that slot. So they let the film go, and now Sony has it. The producers will get their November release date, but it'll be 2009, not 2008. Presumably, everyone's happy now.

But should they be?
Thanksgiving is always a busy time for family films, though, and next year will be no exception. Planet 51's release on Nov. 20 will be just two weeks after Robert Zemeckis' motion-capture A Christmas Carol (starring Jim Carrey) and Wes Anderson's stop-motion The Fantastic Mr. Fox, both of which could be huge.

The premise sounds like it could work, and the screenwriter's credentials check out. But there might be some stiff competition from those other films, which have more star power and might be more visually interesting. What do you think? Can Planet 51 hold its own?