When a distant planet appears as a point of light in a telescope, it's hard to imagine what things are like at the surface. Does rain fall? Is the atmosphere thick, or dissipating into space? How constant is the sunlight on its surface?
Telescopes today are only just beginning to answer that question and get us closer to understanding where extraterrestrial life might exist. As planets transit across the face of their stars, it's possible for astronomers to figure out what chemicals are contained in the planet atmospheres, and to make predictions. However, until now only hot giant planets are observable.
Francois Forget, a senior research scientist with the Meteorological Dynamics Laboratory of the Pierre Simon Laplace Institute in Paris, is part of a group trying to create a model for how planetary atmospheres behave on smaller, rocky planets like Earth, based upon observations in our own solar system. He acknowledges it is limited – we know little about such planets farther in the universe – but the model is a start to learning more about other planets.