Science Fiction Books

The golden days for SF might be on their way back. This gives a chance for new writers to flex their imaginations and their ray guns.

I just finished reading Robert Heinleins book, have space suit will travel, and i was wondering what are some examples of how it is classified science fiction. i know there are aliens but do i have a right to say it is one of the examples to being fiction. what are some specific points in the book about the planets, moon to say that its fiction.

My four year old wants a story book/ picture book about outer space. Preferably kids in a rocket ship exploring other worlds/ aliens or something similar. Thanks!