Nicolaus Copernicus: The Earth Is a Planet
This was a lovely little book about Copernicus. The illustrations were colorful and done in an "old-fashioned" style which made the book feel authentic. The information was interesting and easy for the kids to understand while still explaining clearly what he thought and discovered.
I thought it sufficient for the elementary grades. My fourth-grade boys really enjoyed it, but I almost wished it had been a little longer and more detailed for them. Almost. Any older and you'd probably need a different book.
There are not many children's books on Nicolaus Copernicus. Fortunately, this is a great one. Highly recommended for your study of the middle ages or astronomy.