You can watch PBS Space Time with her for free. The episodes are short. Unless she's an unusually precocious 5 year old, she will not understand much, but you'll learn things that will help you answer her questions, and she'll enjoy the videos and tone and especially that she's watching it with you.
She might also enjoy things like videos that show the relative sizes of planets and different types of stars.
Same goes for Cosmos episodes: let her take what she can from it now; she can come back to them again when she's ready to get more of them. Likewise books - I started buying the Dorling Kindersley books for my nephews when they were 5. Mostly they liked the illustrations and the names, but the books are still with them and now they're reading the text too (they're more about the dinosaurs but the same applies).
Another thing she might enjoy is glow in the dark ceiling star maps. Having real constellations on her bedroom ceiling will be very exciting!