Planet 51(2009)

American astronaut Capt. Chuck Baker begins his space mission to land on planet 51. He is the first human to set foot on that planet, but to his surprise, he encounters green space creatures there. Creatures who live a peaceful and comfortable life and their only problem and fear is the attack of other aliens. Now, Baker, along with his robot named Roar and his space friend, wants to find a way to defeat a group of aliens who want to conquer and destroy planet 51 and return to earth himself.