Chapter 9, An American Ship at the Frontiers of the Solar System, Chapter 10, Sacred Black Summary and Analysis

Neptune was Voyager 2's final destination. It is the penultimate planet, second only to Pluto. Neptune is extremely cold but it has heat in its interior. It was discovered in 1846 and has still not managed to make a complete revolution around the sun. Neptune is four times larger than earth and its blueness is its atmosphere, mostly hydrogen and helium. It also has a Great Dark Spot and rings. Its largest moon is Triton. Sagan then describes Triton in some detail. It bears various similarities to Titan but it has more rock and less ice.

Some scientists speculate that many planets with the building blocks of life exist beyond Pluto and that early events in...