Life On Avalon

So many extrasolar planets are being discovered, including I believe one thought to be similar to Earth, that I am hopeful that some of them might after all be colonizeable, as in Poul Anderson's History of Technic Civilization. In the early 1960's, reading comic strip sf and starting to read sf novels, I took extrasolar planets for granted but was then surprised and disappointed to read in a book by British astronomer, Patrick Moore, that no such planets could be detected. If they were there, then they were too small and far away and not luminous so how could they have been detected? How are they detected now? Gravitational perturbation is one answer. One theory of planetary origin, cited by EE Smith, implied that planets were rare, not the norm.

Poul Anderson knew that, even if some planets were terrestroid, it would not be a simple matter to go and live there as if they were previously undiscovered continents on Earth. Space travelers learn to change their circadian rhythms. Human colonists on Avalon adjust their fluid balance and kinesthesia to 80% G. Ythrian colonists shift their breeding cycle to a different day, year, weight, climate and diet and have low fertility in their first generations but survive and then flourish.

When Rochefort and Helu crash land on an Avalonian island, Helu, grateful to be alive, asks how such a planet has a standard Terran atmospheric pressure. Rochefort explains but, for once, I find it difficult to summarize the technical explanation, on p. 540 of Rise Of The Terran Empire. Ironically, Helu's gratitude is premature. He is soon killed by an Ythrian.

Anderson's vocabulary again: on p. 541, the sea is "...syenite..." This is a kind of igneous rock so Anderson's omniscient narrator or his viewpoint character, Rochefort, must be comparing the colors.