The Sunborn by Gregory Benford (2005)

I expected The Sunborn to continue the story of The Martian Race and to explore the fascinating Martian microbial ecosystem in greater depth. Instead, Benford merges that setting with one of his earlier ideas: intelligent plasma life inhabiting the Sun, a concept that traces back to his fiction from the 1980s. The result surprised me, but it works remarkably well as a standalone novel.

The story shifts much of its attention to the outer Solar System and humanity's expanding presence there while introducing enigmatic plasma beings with their own cosmology, religion, and immense lifespans. Those aliens are genuinely alien in many respects, and Benford preserves enough mystery to maintain a satisfying sense of awe and wonder.

My principal criticism concerns the plasma beings themselves. Although their biology is imaginative, they sometimes react in ways that feel too human. The anthropomorphism occasionally weakens the illusion that they are truly incomprehensible forms of life.

The human side of the story is excellent. The politics and relationships among the people living throughout the Solar System feel authentic, the characters are well written, and the plot is tightly constructed. The story moves from one surprising development to the next without losing momentum. Although the novel was not the sequel I expected, I enjoyed it enormously. 5/5 stars.