While Celeste is fighting off sleep in her room by reading a book about astronomy, she receives an unexpected visit from Moon. Together, they enjoy a journey through the universe to discover what exoplanets are and how they can be detected.

They observe rogue planets, oceanic worlds and super-earths. Moon tells her about exoplanet hunters who observe the sky in search of planets such as Earth. Many adventures are yet to come. But first, she needs some rest. Celeste drops off to sleep waiting for the next visit of Moon.