Sunday, 27 October 2013

The Astronomy Of Virgin Planet

The astronomy of Poul Anderson's "Virgin Planet" is confusing so it is helpful to consult the Author's Note in the longer version, Virgin Planet.

Caput Lupi, the Wolf's Head, is a constellation visible from Nerthus, a colonized terrestroid planet of Carsten's Star, which is about a thousand light years from Sol towards Argus. The four brightest stars in Caput Lupi are Alpha, Beta, Gamma and Delta Capitis Lupi, respectively.

Delta is a double star:

hot blue A, called Daedalus, has three uninhabitable planets;
Sol-like B, called Icarus, has two planets, including the eighteen-mooned gas giant, Minos.

The third Minoan moon, Atlantis, Earth-sized and colonized, is the "Virgin Planet." Thus, the story is set on one of the eighteen moons of one of the two planets of one of the two companions in the fourth brightest star of a constellation visible a thousand light years from the Solar System.

The (inhabited) "inner hemisphere" of Atlantis is the side permanently facing Minos. Anderson presents tables for the equatorial diameters, orbital radii and periods, angular diameter from Atlantis and times between oppositions to Atlantis for the five inner moons. All of this information cannot be incorporated into the text of the novel but it nevertheless determines the Atlantean environment in ways that affect the story.

As Brian Aldiss remarked once, a hard sf writer works harder than a mainstream novelist.

See also Atlantean Astronomy.

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