A subjovian planet should retain a large quantity of hydrogen and helium. However, the extra-solar subjovian, Paradox, captured an asteroid which became a moon with an eccentric orbit. Passing through the Paradoxical atmosphere, the moon blew large numbers of lighter molecules into space before breaking up and crashing onto the surface. Metallic atoms spread across the planet might have combined with any remaining hydrogen. The atmosphere became early terrestroid: carbon dioxide, water vapor, methane, ammonia etc, except for more helium than usual. Life and photosynthesis began, generating an oxynitrogen atmosphere. Despite fifteen Terrestrial masses, Paradox is solid with a humanly breathable atmosphere.
Another large planet that loses its hydrogen and helium, gaining an inhabited solid surface, is Ramnu. (Scroll down.)
1 comment:
Kaor, Paul!
I reread "A Little Knowledge" a few months ago in Florida. The story is about how risky it can be to judge other people solely on one's first impressions of them. Which was the mistake made by the villains in this tale.
Ad astra! Sean
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