Clouds are not only something to watch, but actually impact the weather a great deal. This is true here on Earth and on Kepler 7b, a planet roughly a thousand light years away. Using NASA's Kepler and Spitzer Space Telescopes, researchers at MIT have successfully observed the cloud patterns of an exoplanet for the first time.
A couple years ago, researchers were analyzing the reflectivity of Kepler 7b and noticed that it is very bright for an exoplanet. The exact cause of this was a mystery at the time, but by combining the data from the two telescopes, the researchers are confident much of the reflectivity is caused by the clouds. The planet is considered a hot Jupiter, which means it is a gas giant, like Jupiter, though 1.5 times larger, but orbits its host star very closely. It is actually close enough that the planet is tidally locked to the star, which means only one side ever faces it. By measuring the reflected light during each orbital phase, the researchers were able to determine that the explanation for the high reflectivity is clouds.
Interestingly, while one side of the planet is completely overcast, the researchers have noted that the distribution of clouds leaves the other hemisphere completely clear. The exact mechanism that forms the clouds is not known.