Hermian type worlds

Dense, inner system worlds

Hermes
Image from Steve Bowers
Hermes, a Hermian world in the Tau Ceti system
(formerly Mercurian type)
These worlds have a relatively large core and a high metal content, but there remains a lighter, rocky crust as well. These worlds may be formed in a similar manner to Ferrinian planets, but at a further orbit from their sun, or they may be formed after suffering a cataclysmic impact during the formative period, in which most of the lighter rocky material is blasted out into space. These planets are heavily cratered, with some signs of primordial geologic activity. Their atmospheres are non-existent, save for a trace layer of helium being constantly replenished and stripped by the stellar wind.

Examples Mercury, Hermes
 
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Development Notes
Text by John M. Dollan

Initially published on 18 November 2008.