After an introduction to exoplanets - planets orbiting stars other than the Sun - Alien Earths concentrates on the theory of and the search for life on these planets. Written by astronomy professor Lisa Kaltenegger, who runs the Carl Sagan Institute for the Search for Life in the Cosmos at Cornell University, it's a gentle guide to one of the most imaginative aspects of astronomy. A fair amount of the content looks at what makes a habitable planet (which is not always an Earth-like situation), what life is and how we may be able to detect it a great distance. There are some good details here, though I would have appreciated more depth. Given this is such a speculative subject, there is also relatively little questioning of assumptions. For example, there's a description of the gold records sent out on Voyager 1 and 2, with detail of how to put a time interval across to aliens. 'The team [behind the records] solved this problem by using a time constant that any spacefaring c
Reading this novella was a strange experience. It was more like watching an episode of an SF anthology TV series such as The Twilight Zone or Black Mirror than reading a book. Like these, there is limited character development and a restricted plot with interesting ideas, but not a full story arc. It did made me wish Adam Roberts had fleshed it out to a full novel - I could see so many more opportunities that were unfulfilled - but like the better episodes in the TV shows, as long as you take it for what it is, it's still a fun experience. The central character Hi (a name with echoes of Snow Crash 's Hiro Protagonist) is a very talented future mercenary. Taking on the job of liberating an extremely rich woman's daughter from the girl's father's fortified home on Mars, Hi achieves the impossible in getting to Mars without being discovered and killed (Roberts toys with us as to how this could have happened), and then sets about preparing for a ridiculously David an