My 7yo boy is interested in astronomy, so I ordered the
"My Favorite Universe" course by Neil deGrasse Tyson from The Great Courses. The suggested readings for the course are below. I think they are written for the general reader, and they have good reviews on Amazon. Other book suggestions are welcome.

Black Holes and Time Warps: Einstein's Outrageous Legacy
by Thorne, Kip

Cosmic Catastrophes: Supernovae, Gamma-Ray Bursts, and Adventures in Hyperspace
by Wheeler, J. Craig

Five Ages of the Universe
by Adams, Fred & Laughlin, Greg

One Universe: At Home in the Cosmos
by Tyson, Neil deGrasse, Liu, Charles

Rain of Iron and Ice
by Lewis, John S.

The Character of Physical Law
by Feynman, Richard P.

The Search for Life in the Universe
by Goldsmith, Donald and Owen, Tobias

A couple of fun reads about astronomy are the "George" series by Steven Hawkings and his daughter. (George's Secret Key to the Universe and George's Cosmic Treasure Hunt)
DD8 tore through them, loved the photos and when we went to a local star party asked one of the retired astronomy prof's there all sorts of good questions that she came away with. I
I don't know who came away more impressed - DD because the man not only knew the answers to her questions but was very willing and able to discuss them with her, or him because here it was in the middle of a field and he is being quizzed by a then 7 yr old about some of the newest ideas in astronomy. (I wish I could have seen his expressions more )