has part has part has_part composed primarily of planetary surface planet ice ice planet envoAstro cryoplanet While this planetary form is still mostly theoretical, strong candidates exist such as OGLE-2005-BLG-390Lb, OGLE-2013-BLG-0341L b and MOA-2007-BLG-192Lb. Pluto was considered an ice planet until its reclassification in 2006 CE. Surface temperatures of ice planets would have to be below 260 K (−13°C) if composed primarily of water, below 180 K (−93°C) if primarily composed of CO2 and ammonia, and below 80 K (−193°C) if composed primarily of methane. A planet which has a surface layer that nearly completely or completely covered by ice, and which has a substantial portion of its mass composed of ice.