氣態巨星是行星等級中的B級（Class B）行星，與 Class A （氣態超巨星）行星相似, 出現在恆星系中的 "冷區"比 Class A 行星略小, 直徑通常在 50,000~140,000 公里地核溫度高但輻射的熱量不如 Class A 行星那么多行星表面同樣充滿氫氣及其化合物, 導致低輻射及強大重力典型的 Class B 行星是土星
Class B (Gas Giant):
Class B planets, like Class A planets, are also found in a star's
"cold zone". They are smaller than Class A planets and are usually between
50,000 and 140,000 kilometers in diameter. They have high core temperatures
but do not radiate as much heat as Class A planets. Their surface is also
composed from gaseous hydrogen and hydrogen compounds, due to the low stellar
radiation and high planet gravity. An example of a Class B planet is Saturn.
