Class I - Gas Supergiant
Age: 2-10 billion years
Diameter: 140,000 - 10 million km
Location: Cold Zone
Surface: Tenuous, comprised of gaseous hydrogen and hydrogen compounds; radiates heat
Atmosphere: Zones vary in terperature, pressure and composition; water vapor may be present
Class I planets are generally found in a star's outer cold zone. Aptly called super giants, they range in size from 140 thousand to 10 million kilometers in diameter. Because they have such a high core temperature, they radiate heat. High gravity combined with low stellar radiation enables them to maintain a tenuous surface comprised of gaseous hydrogen and hydrogen compounds. This environment is not suitable for known life forms.