Alexis and Alice are sitting on their home's balcony, gazing at the sky. They know that Earth is a welcoming planet - the only one in our solar system that hosts life! But, like all humans, our two little friends want to learn everything about the sky. They dream that one day they will board a spaceship and travel to Mercury, Venus, Pluto, Mars... And then, they will visit other solar systems, distant and unknown. After all, people have always studied the sky, trying to uncover the truth: Is there, perhaps, life on other planets?