A friend of ours has asked us if we know of any books on Astronomy (or any science for that matter) suitable for a 7yo. The boys particular interests are fossils, dinosaurs (naturally!!), rocks and planets.
My grandchildren, ages from 7 up to 13, eagerly wait for a UK publication on these subjects called Aquila. I've been sending them a subscription for a couple of years and they love it. You can order a free trial at : info@aquila.co.uk.