Simplify the following text for a Grade 9 native English-speaking person.
Original: In Celtic mythology and English folklore , a Puck is a mischievous sprite , imagined as an evil demon by Christians ; the moon is named after the Puck who appears in Shakespeare 's A Midsummer Night 's Dream , in which he travels around the globe at night with the fairies .
Simplified: The moon was later named after the Puck who appears in Shakespeare 's A Midsummer Night 's Dream , a little sprite who travels around the globe at night with the fairies . In Celtic mythology and English folklore , a Puck is a mischievous sprite , imagined as an evil demon by Christians .