One of first transiting exoplanets discovered by Kepler announced in a batch of 5 Jan 2010 (Kepler 4-9). It, like the others, is a hot Jupiter. It is the largest of the batch in diameter, its mass is 50% of Jupiter's, but its diameter is 50% greater than Jupiter, making its density that of styrofoam. This is the least dense planet found to date. It is also particularly bright for a Hot Jupiter, and has about three times the albedo of the typical one. This reflected light came from high altitude clouds in the west. Spitzer was able to measure the temperature of the bright spot in the hemisphere, which was too cool for a hot jupiter at this distance, so was interpreted as reflective clouds. The skies are clear on the east side, where it is hotter. The cloud structure, the first to be observed for an exoplanet, is stable over time. Being too hot for water clouds (though less hot than many Hot Jupiters), these clouds are probably made of silicates and magnesium. If made from perovskite or forsterite, the clouds could have a greenish tint.