A new study by McGill University astronomers has found that the temperature on the nightsides of different hot Jupiters is surprisingly uniform, suggesting the dark side of these massive gaseous planets have clouds made of minerals and rocks.  

Using data from the Spitzer Space and the Hubble Space telescopes, the researchers from the McGill Space Institute found that the nightside temperature of 12 hot Jupiters they studied was about 800°C.