Class T - Ultragiant
Age: 2-10 billion years
Diameter: 50-120 million km
Location: Cold Zone
Surface: Tenuous, composed of gaseous hydrogen and hydrogen compounds; radiates considerable heat
Atmosphere: Zones vary in termperature, pressure and composition; water vapor may be present
Class T planets generally are found in a star's cold zone. Essentially they are the same as Class S planets, differing only in size, which ranges from 50 to 120 million kilometers in diameter. Their high core temperatures radiate considerable heat, causing water to be present in vapor form. The harsh environment makes them unsuitable for humanoid life.