Image from Steve Bowers

Massive object resulting from the coalescence of planetesimals in the solar nebula, which eventually becomes a mature planet. Protoplanets are constantly impacted by other objects in the protoplanetary swarm, so are often very hot, with a molten or semi-molten surface.

Has a thick primary atmosphere, generally of hydrogen and helium, much of which will be lost unless the planet gains enough mass to become a gas giant. Because of the potential for mining and megascale engineering, protoplanets are often highly sought after by interstellar development corporations and certain clades and hyperturings.

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Development Notes
Text by M. Alan Kazlev and Steve Bowers
Initially published on 19 December 2001.