The Shrouded Planet by Robert Randall

NIDOR LAY WRAPPED IN ETERNAL CLOUDS

The people of Nidor lived by the Law and the Scripture, remembering always the Great Cataclysm that had nearly destroyed their world only five thousand years before. They gave thanks daily to the Great Light that had spared their ancestors, and knew that only respect for tradition would keep their children safe.

Then the strangers arrived-falling from the clouds and clothed in light.

They called themselves Earthmen.

THE SHROUDED PLANET