Take them to observatories (or just high in the mountains to show the stars), visit planetariums, make calls with astronauts, us AR solutions to show them beauty behind the hard maths - and definitely teach maths behind the all beauty. There's nothing that can stop you from teaching astronomy early in the school, but you should be aware of what other subject you're ready to sacrifice in order to avoid overload of your students.
Use myths and other stories. Catch the attention of the students with a storyteller (if you don´t feel like doing it yourself). Disguise and act. A colour of music could help to (you play guitar?). Touch their heart and their head will follow. Regards.
Show the relevance of the subject to students' daily lives in the present and future and engage them in experiences that would develop their knowledge and skills thru application both in and outside the classroom.