Carl Sagan is an astronomy Professor at Cornell University and author of a dozen books and a recipient of the Pulitzer Prize. His Cosmos (1980), which appears to be a follow-on to the thirteen-part TV series that he did on the same subject, is a colorful and breezy summary of the universe’s estimated 15 billion-year-history, with special emphasis on the various spacecraft missions by the U.S. and Russia.
To be fair, his Cosmos has been surpassed by more recent and better books, such as Bill Bryson’s brilliant summary of what makes the world work in his Short History of Almost Everything and more technical ones, like Brian Greene’s Elegant Universe, Hawking’s mind-bending Brief History of Time, and Stephen Jay Gould’s captivating Wonderful Life. While Cosmos remains user-friendly for the most part and still informative, especially for children, Bryson’s Short History will provide much more and better-organized data, and even its illustrations are more edifying for people of all ages, including children.
By all means, read Cosmos and share it with your children, as it is well known and should be installed in their memory banks, but be sure to add Bryson's Short History of Almost Everything and Gould's Wonderful Life.