Class H - Desert
Age: 4-10 billions years
Diameter: 8,000 - 15,000 km
Location: Hot, Ecosphere, or Cold Zones
Surface: Hot and arid, little or no surface water
Atmosphere: May contain heavy gases and metal vapors
Life-Forms: Drought and radiation-resistant plants, animal life
Examples: Tau Cygna V
Most often found within a star's habitable zone, Class H planets may reside in any zone. Somewhat smaller than Earth, they range in size from 8,000 to 15,000 kilometers. Class H planets have a molten core and a dry, barren rock surface, with a thin primarily carbon dioxide atmosphere. Oxygen is generally only present in small amounts, along with trace gases such as argon and xenon. Iron rich desert-like plains, dry valleys and canyons, and occasional volcano or mountain range mark the surface. Although conditions are inhospitable, they are capable of supporting simple plant life and insects.
Tau Cygna V, a desert planet bathed in hyperonic radiation, is Class H. A Federation colony was established there in violation of the Treaty of Arms in "The Ensigns of Command" (TNG).