Blue Moon is covered in life-giving water and an atmosphere so dense that enormous creatures can take flight. The Blue Moon orbits a Water Cloud Jovian planet (a Jupiter-like planet that is cool enough to have visible rain clouds in its atmosphere) orbiting a close binary star system. The Blue Moon itself is roughly an earth mass but has an air pressure around three times that of Earth's at sea level. A distinguishing feature of Blue Moon is that it has no polar ice caps: the thick atmosphere keeps temperatures constant across the moon's surface. There is also a greenish haze over the moon from large carpets of floating moss and algae. The denser atmosphere allows more massive creatures to remain airborne than on Earth. Skywhales, gargantuan whale-like animals which evolved away from the ocean into the air, fill the ecological niche this creates. Because of the increased muscle power from excess atmospheric oxygen, these creatures can have wingspans of ten meters and remain airborne their entire lives. They feed on the previously mentioned air moss. They evolved from sea-going animals into flying ones in one evolutionary leap.