 Most solar system planets have large atmospheres. Each atmosphere has its own dramatic weather systems. They carry heat, gases and particles. The long-term pattern of weather is called climate. The earth today is a vibrant blue planet. Our atmosphere and oceans form a complex, evolving system. This climate system is essential to life. Great extinctions of the past are linked to changes in climate. We think that the climates of our nearest neighbours, Venus and Mars, have both changed too. In the lecture, I will discuss the dynamic role played by atmospheres and how understanding those of other planets might teach us more about our own.