Here's some great ones:
http://www.harpercollinschildrens.com/Kids/SeriesDetail.aspx?PSId=224
Here is some great books on space for preschool to early elementary.

Let's read and find out science books, The Planets in Our Solar System
(This is a large series, I've found these used and at the library & on ebay , we can't get enough of these)

Little Rocket's special Star by Julie Sykes

If you decide to go to the moon by mcnulty

On the moon by milbourne