How it’s done
A blanket, the rooftop or the beach or the yard, whatever lights can be turned off — and time. You don't need to know astronomy: the child's questions and an "I don't know, what do you think?" go further than a class.
If you want structure: find the moon and its spots, count shooting stars in August, tell a star from a planet from a plane from a satellite. If not, the conversation that comes out on its own in the dark — with no faces to look at — is usually the best part.
What it builds — the why
Wonder as a habit — the raw material of scientific thinking — and a rare, valuable setting: conversation in the dark, shoulder to shoulder, where hard topics come out more easily because nobody's looking at anybody.
How it changes with age
3–5 Early childhood
6–9 Childhood
10–12 Preteens
13–15 Early adolescence
16–18 Adolescence
What to watch for in your child
Does your daughter ask outward (planets, distances, aliens) or inward (what are we, what happens when we die)? Both are astronomy in their own way. And if she falls asleep after fifteen minutes, the activity worked too.