This is a well-written popular science book. Full of specialist content from astronomy and physics but written in a very accessible language. It should be taken into account that the author wrote it in 1980 shortly after the launch of the Voyager 1 and 2 space probes, on the construction of which Carl Sagan worked. (these probes are currently located on the outskirts of the solar system).
There is a lot of information here that may be difficult for an ordinary person with no idea about physics to absorb. Fragments of historical and biographical introductions also provide a good balance to the flood of such information.
Each chapter presents a different topic on the subject of space and in each of these chapters Carl Sagan presents the historical context of a given issue. Who dealt with this topic earlier (than we do today)? What did people several hundred years ago know and what did they not know? How has their perception of space changed over the centuries? A lot of space is devoted to ancient Greece.
The author emphasizes here his great respect for the incredible knowledge that people of that time had. Thanks to this, we will also see that our knowledge was not created here and now, but has evolved over hundreds or thousands of years.