Sudarsky had , on the assumption that the planet is similar to Jupiter in composition and that its environment is close to chemical equilibrium , predicted Upsilon Andromedae b to have reflective clouds of silicates and iron in its upper atmosphere . The cloud deck instead absorbs the sun 's radiation ; between that and the hot , high pressure gas surrounding the mantle , exists a stratosphere of cooler gas . The outer shell of dark , opaque , hot cloud is assumed to consist of vanadium and titanium oxides ( " pM planets " ) , but other compounds like tholins cannot be ruled out yet .